Home Green synthesis and studies on citrus medica leaf extract-mediated Au–ZnO nanocomposites: A sustainable approach for efficient photocatalytic degradation of rhodamine B dye in aqueous media
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Green synthesis and studies on citrus medica leaf extract-mediated Au–ZnO nanocomposites: A sustainable approach for efficient photocatalytic degradation of rhodamine B dye in aqueous media

  • Tiba Ibrahim , Luma Hakim Ali , Wisam Aqeel Muslim , Karrar Hazim Salem , Kahtan A. Mohammed EMAIL logo , Rahman S. Zabibah , Mohammed Ayad Alkhafaji , Zahraa Falah Khudair , Shubham Sharma EMAIL logo , Emad Makki ORCID logo EMAIL logo and Mohamed Abbas
Published/Copyright: May 15, 2024
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Green Processing and Synthesis
From the journal Green Processing and Synthesis Volume 13 Issue 1

Abstract

Incorporating narrow band gap oxide semiconductors and metals into zinc oxide (ZnO) nanostructures broadens the range of light sensitivity to include visible wavelengths. In this study, the photocatalytic degradation of rhodamine B (RhB) dye was studied as a model for environmental pollution in aqueous media. This study describes the use of photodegradation catalysts, including gold (Au), ZnO, and Au–ZnO nanocomposites (prepared in ratios of 90:10 and 95:5) using the extract of Citrus medica leaves. X-ray diffraction (XRD) findings have shown that ZnO nanoparticles (NPs) have a hexagonal wurtzite structure. Field emission-scanning electron microscopy findings have depicted that ZnO NPs have diverse shapes, including spherical, quasi-spherical, hexagonal, and anisotropic, with some clumping. Au exhibits consistent spherical shapes and sizes with even distribution. Au–ZnO (90:10) shows quasi-spherical NPs with interconnected spherical Au, forming a porous and uneven surface. Au–ZnO (95:5) has spherical gold nanoparticles (Au NPs) dispersed on a textured ZnO surface, with some clustering and size variation as evident from the transmission electron microscopy, atomic force microscopy, and diffuse reflectance UV-visible spectroscopy analysis. The characterization results have demonstrated the uniform distribution of Au across the ZnO lattice. Additionally, the XRD patterns confirmed the hexagonal wurtzite structure of ZnO. Furthermore, energy-dispersive analysis of X-ray (EDX)-mapping verified the inclusion of zinc, oxygen, and Au in the hybrid Au–ZnO nanocomposites and their effective distribution. The topological analysis revealed a rough surface for the generated nanostructures. By comparing the results of various techniques, EDX analysis using atomic and weight ratios confirmed the presence of oxygen and Au in the nanocomposite. Additionally, the surface area analysis (BET) test has reported that the adsorption and desorption of nitrogen follow a Type III isotherm. The presence of an H3-type hysteresis loop further confirms the mesoporous nature of the composites, which reports the presence of wedge-shaped pores. The Au–ZnO (90:10) nanocomposite exhibits a higher surface roughness compared to other composites. In addition, this UV-visible diffuse reflectance spectroscopy has enumerated the band gaps of various nanomaterials using UV-visible spectroscopy. Moreover, the analysis has unveiled that combining ZnO with Au NPs (doping) improved the photocatalytic performance of ZnO. This improvement is attributed to the formation of additional energy levels within the ZnO band gap due to the presence of Au ions. Experimental investigation of the breakdown of RhB dye under visible light irradiation revealed superior photocatalytic activity for the Au–ZnO (90:10) nanocomposite compared to both Au–ZnO (95:5) and pure ZnO and Au counterparts. Multiple experiments confirmed the effective photodegradation and removal of RhB dye from the aqueous medium using the nanocatalyst under visible light irradiation. Under optimal conditions (1.0 g·L−1 photocatalyst, 10 ppm RhB, and pH 10), 99% photodegradation efficiency was reached within 50 min of irradiation. Investigation of reactive species revealed that the increased effectiveness of photodegradation in Au–ZnO (90:10) stems from the presence of photogenerated holes and hydroxyl radicals. The study also analyzed the reaction kinetics and order, and the reusability of the best photocatalyst Au–ZnO (90:10)) was confirmed through five consecutive cycles, demonstrating its sustained effectiveness in photodegradation. These findings highlight the potential of Au–ZnO (90:10) nanocomposite as a promising material for photocatalytic degradation of organic dyes.

Keywords: Au; ZnO nanocomposite; eco-friendly; photodegradation; rhodamine B dye

1 Introduction

Environmental pollution and its cleanup have garnered significant attention worldwide due to the severe damage it inflicts on aquatic environments, humans, and other animals. Industrial effluent, posing a major threat, is one of the key contributors to this problem [1]. While increasing pollution and population remain pressing global issues, the escalating need for water, particularly within the developing industrial sector, is further exacerbating water source contamination and creating significant environmental challenges [2].

The discharge of pigmented waste materials poses a highly perilous ecological threat, escalating the contamination of aquatic ecosystems. Textile dye pollution, a prevalent issue, has detrimental effects on both the aquatic environment and the health of animals and humans. This contamination primarily stems from the rise in chemical and biochemical oxygen demand (COD and BOD), leading to a decline in photosynthesis, stunted plant growth, and bioaccumulation throughout the aquatic food chain [3]. New paths for developing advanced pharmaceutical treatments and analytical procedures have emerged thanks to advancements in wastewater treatment. Combinatorial therapies targeting both organic and biological toxins are crucial to prevent natural resource depletion, particularly water, caused by various industries like agriculture, paper, and leather [4]. Notably, industrial dyes (e.g., rhodamine 6G, methyl orange, methylene blue) and infectious microorganisms (e.g., Corynebacterium glutamicum, Escherichia coli, Bacillus subtilis) can exacerbate the impact of these pollutants, potentially increasing carcinogenicity and life-threatening effects.

Photocatalysis has emerged as a highly effective method for wastewater cleanup due to its advantages over alternative approaches [5]. It is recognized for its ability to completely mineralize various non-biodegradable organic contaminants found in aquatic environments, making it a viable strategy for removing several pollutants from wastewater. Zinc oxide (ZnO) is a well-researched photocatalyst due to its exceptional physical and chemical properties. It is widely recognized as an n-type oxide semiconductor with a significant band gap energy (E g) of 3.35 eV [6]. The band gap energy of ZnO varies between 3.1 and 3.4 electron volts (eV), showing sensitivity to factors like synthesis methods and crystal size/morphology. This versatility makes ZnO a highly valuable material, thanks to its rapid oxidation potential, resistance to biological and chemical interactions, strong redox capacity, non-toxicity, affordability, and environmental friendliness.

The escalating contamination of aquatic ecosystems by pigmented waste materials, particularly textile dyes, poses a significant environmental threat. These pollutants have detrimental effects on the aquatic environment and can lead to various diseases in animals and humans. Increased COD and BOD caused by these contaminants disrupts photosynthesis, hinders plant growth, and leads to bioaccumulation throughout the food chain [7].

ZnO has seen widespread adoption in diverse fields, including biosensing, adsorption, solar cells, photocatalysis, and various medical and biological applications. However, its wide band gap typically limits its photocatalytic activity to ultraviolet (UV) light. While bare ZnO exhibits limited activity in the visible light range, specific modifications like self-sensitization and vacuum deoxidation can unlock its potential to harness solar radiation for photocatalysis [8,9].

ZnO can be modified through various techniques, including the addition of metal nanoparticles (NPs) like silver (Ag), iron (Fe), gold (Au), palladium (Pd), and copper (Cu). These modifications aim to address ZnO's large band gap energy, which limits its photocatalytic activity [10]. Notably, gold nanoparticles (Au NPs) are valuable in bioimaging, biomedical treatments, and diagnostics due to their biocompatibility, low toxicity, and ease of detection. When combined with oxide semiconductors, Au NPs enhance visible light absorption and charge separation, ultimately improving photocatalytic efficacy [11,12].

Another strategy involves mixing ZnO with semiconductors with narrower band gaps, such as Au, Ag, or Cu, or carbon nanomaterials like graphene oxide (GO), reduced GO (rGO), or carbon dots. This approach effectively adjusts the ZnO band gap, creating materials that are highly active under visible light. Additional methods like heat treatment, dye sensitization, and plasma treatment can also modify the optical band gap of ZnO [13].

Incorporating narrow-band gap oxide semiconductors and metals into ZnO nanostructures broadens the range of light sensitivity to include visible wavelengths. For example, Au undergoes a triple oxidation process, transitioning from its elemental form (Au) to a +3-oxidation state with a smaller band gap compared to ZnO [14]. Integrating Au NPs with zinc oxide nanoparticles (ZnO NPs) facilitates efficient charge carrier separation and band alignment, thereby influencing the band structure of ZnO and enhancing photoelectron transfer [15,16]. Recent research findings have revealed that the introduction of photogenerated electrons from Au into ZnO leads to a notable enhancement in photocatalytic performance for several applications, including wastewater treatment, organic dye degradation, and dye-sensitized solar cells [17].

When comparing the previous method of preparing nanomaterials with the modern method, we find that the traditional chemical-based method for preparing nanomaterials is considered hazardous and harmful to the environment, toxic, and economically costly. A global movement has recently emerged towards producing nanocatalysts using more environmentally friendly methods.

Botanical extracts, employed in environmentally safe processes, have been used to biosynthesize ZnO NPs using bacteria, fungi, and algae. Plant extracts from various parts, such as roots, flowers, leaves, stems, seeds, and fruits, have also been utilized. Green synthesis allows for large-scale production of ZnO NPs with fewer undesired impurities.

A binary Au–ZnO nanocomposite was created using Citrus medica leaf extract as an easy, safe, environmentally friendly, harmless, and non-toxic method. This biological method is also economically inexpensive.

These nanomaterials were used as catalysts for the photodegradation of rhodamine B (RhB) dyes, a model for environmental pollution in the aqueous medium. This process purifies water from pollutants and contributes to the degradation of wastewater pollutants.

Only a few publications have been published on the environmentally friendly production of hybrid Au–ZnO nanocomposites utilizing plant extracts.

To analyze the as-fabricated nanomaterials, the main technique used was X-ray diffraction (XRD). XRD analysis revealed the angles for each prepared sample, as well as Miller’s coefficients for these angles, confirming the success of the preparation process.

2 Experimentation

2.1 Materials

All materials used are highly efficient and can be used without further purification due to their high purity. The following substances were bought from B.D.H.: zinc(II) nitrate hexahydrate (Zn(NO3)2·6H2O; purity, 99.5%), hydrogen tetrachlorocuprate(III) hydrate (HAuCl4·3H2O; purity, 99.9%) from B.D.H. and RhB dye (empirical formula: C28H31ClN2O3; purity, 97%; maximum wavelength of 553 nm) was purchased from Sigma-Aldrich, and hydrochloric acid (HCl, 37 %) was purchased from B.D.H. and sodium hydroxide (NaOH, 99%) from Scharlau. Deionized (DI) water was used to prepare all the solutions.

2.2 Preparation of the aqueous extract of Citrus medica

The study utilized Citrus medica leaves that were freshly harvested from an open field located in Babylon, Iraq. The leaves were subjected to a thorough washing process using DI water. Subsequently, the specimen was allowed to remain undisturbed at ambient temperature within a controlled atmosphere devoid of particulate matter, with the aim of mitigating the potential evaporation of volatile organic compounds. The leaves were thereafter severed and immersed in 75 mL of DI water prior to being subjected to a temperature of 80°C for a duration of 30 min, accompanied by intense agitation. The extract was further subjected to filtration using Whatman No.1 filter paper and centrifugation at a speed of 6,000 rpm for a duration of 10 min, aiming to eliminate minute suspended particles. The final volume was adjusted to 100 mL by the addition of DI water. Subsequently, in order to facilitate the utilization of the clear extract in the process of synthesizing nanomaterials, it was stored at a temperature of 4°C.

2.3 Synthesis of ZnO and Au NPs

ZnO NPs were synthesized using a leaf extract in an environmentally friendly approach. A 50 mL aqueous extract of Citrus medica was used to dissolve 0.5 g of Zn(NO3)2·6H2O under continuous magnetic stirring at 80°C for 4 h, reducing it to Zn²+ ions. The solution was centrifuged at 6,000 rpm for 20 min to remove residual reactants and prevent photoreactions. Wrapped in aluminum foil, it then rested at room temperature for 24 h. The resulting dark precipitate was repeatedly washed with DI water and ethanol to remove impurities. Finally, it was dried at 80°C for 4 h, yielding a pale white solid. The color change from yellow to white confirmed the conversion of zinc nitrate to zinc ions and the formation of ZnO NPs. For comparison, Zn(NO3)2·6H2O dissolved in only DI water failed to precipitate ZnO under the same conditions.

Au NPs were synthesized similarly. However, 0.5 g of HAuCl4·3H2O (99.9%) was dissolved in the Citrus medica extract and then calcined to form yellow-colored Au NPs.

2.4 Synthesis of Au–ZnO (90:10) and Au–ZnO (95:5) nanocomposites

The nanocomposite Au–ZnO (90:10) was prepared in a typical experiment where 50 mL of the aqueous Citrus medica extract was dissolved in 4.09 g·L−1 Zn (NO3)2.6H2O and 0.19 g·L−1 hydrogen tetrachlorocuprate (iii) hydrate (HAuCl4·3H2O 99.9%), which was then subjected to 4 h of continuous magnetic stirring at 80°C. The mixture was next covered with a heavy metal foil and allowed to sit at room temperature for 24 h to avoid any photoreactions. At 6,000 rpm, the reaction mixture was centrifuged for 20 min. The resultant precipitate was thoroughly cleaned of any adsorptive impurities using DI and ethanol before being dried for 4 h at 80°C to produce a light blue solid. The powder was then calcined at 500°C for 4 h. The same procedures as above were used to create conjugated Au-ZnO (95:5) in various ratios by altering the proportions of the initial substances involved in the reaction. This was done by adding 0.09 g·L−1 of hydrogen tetrachlorocuprate(iii) hydrate (HAuCl4·3H2O 99.9%) to a plant extract solution that contained 4.32 g·L−1 of Zn(NO)2·6H2O.

3 Results and discussion

3.1 XRD

The XRD peaks of ZnO NPs match the hexagonal wurtzite phase of ZnO (JCPDS 21-1732). Specific peaks at 31.5020° (100 planes), 34.2340° (002 planes), and 36.2716° (101 planes) confirm ZnO synthesis, consistent with previous studies [18]. As shown in Figure 1, the monoclinic XRD pattern of Au NPs indicates pure Au (JCPDS 73-1839). The peaks at 38.1733°, 44.3202°, and 64.5334° correspond to Au NP lattice planes (111), (200), and (220), respectively, aligning with previous reports [19].

Figure 1 Diffraction patterns of Au–ZnO (90:10) and Au–ZnO (95:5) nanocomposites prepared using ZnO and Au.
Figure 1

Diffraction patterns of Au–ZnO (90:10) and Au–ZnO (95:5) nanocomposites prepared using ZnO and Au.

The XRD pattern of the Au–ZnO (90:10) nanocomposite aligns with the expected Au–ZnO structure based on the data (JCPDS 92-1793). Prominent peaks at 38.540° and 44.743° correspond to the (111) and (200) planes of Au, respectively, indicating the growth of Au nanoparticles on ZnO surfaces. Notably, Au incorporation alters diffraction intensities and reduces crystallite sizes of ZnO NP. Nonetheless, ZnO NPs maintain their structural integrity.

Similar diffraction intensity changes and decreased crystallite sizes are observed in Au–ZnO (95:5) (JCPDS 27-1375) nanocomposites. Again, the XRD pattern confirms the structural integrity of ZnO NPs after Au incorporation. Interestingly, a singular, low-intensity peak at 38.708° (111) suggests the presence of some Au [20,21].

The crystallite sizes calculated using the Debye–Scherrer equation are presented in Table 1.

(1) D = K λ β × cos θ

Table 1

Calculated nanocrystallite sizes of synthesized nanomaterials from XRD analysis (in nm)

Material 2Ө Miller indices Lattice strain Intensity I/I° d-spacing (Å) Average size (nm)
ZnO 31.5020 100 0.0019 61 2.72011 16.30
34.2340 002 0.0075 43 2.61966
36.2716 101 0.0054 100 2.43120
Au 38.1733 111 0.0046 95 2.3217 24.34
44.3202 200 0.0027 100 2.2171
64.5334 220 0.0067 23 1.7675
Au–ZnO (90:10) 31.776 100 0.0061 63 2.83272 35.07
35.547 002 0.0053 46 2.51244
36.839 102 0.006 100 2.49182
38.540 111 0.0051 70 2.7438
31.825 100 0.0058 60 2.28732
35.680 022 0.0043 48 2.24514
Au–ZnO (95:5) 36.973 102 0.0045 100 2.18492 32.6
38.708 111 0.0065 86 2.4378
44.894 220 0.0061 97 2.4783

The full width at half-maximum (FWHM) of the XRD peaks and the diffraction angle are all constants, while D is the size of the crystallite, and K is a constant of 0.9.

3.2 Field-emission scanning electron microscopy (FE-SEM)

FE-SEM analysis revealed diverse surface morphologies for ZnO, Au, and their Au–ZnO nanocomposite (Figure 2). ZnO NPs exhibited a variety of shapes, including spherical, quasi-spherical, hexagonal, and anisotropic, with some particle agglomeration. The biosynthesized Au displayed consistent spherical shapes and sizes with uniform distribution.

Figure 2 (a–d) FE-SEM images of the ZnO, Au, and Au–ZnO (95:5) and Au–ZnO (90:10).
Figure 2

(a–d) FE-SEM images of the ZnO, Au, and Au–ZnO (95:5) and Au–ZnO (90:10).

Au incorporation modified ZnO morphology. The resulting Au–ZnO nanocomposite showed quasi-spherical NPs with interconnected spherical Au NPs, creating a porous and uneven surface according to FE-SEM micrographs.

For the Au–ZnO (95:5) nanocomposite, FE-SEM images revealed favorably dispersed spherical Au NPs on a textured ZnO surface, with some clustering and uneven size distribution. The presence of spherical particles on the Au–ZnO surface confirmed the formation of the nanocomposite [22] (Figure 3).

Figure 3 (a–c) Image mapping representing the elements zinc, Au, and oxygen of the prepared nanocomposite.
Figure 3

(a–c) Image mapping representing the elements zinc, Au, and oxygen of the prepared nanocomposite.

3.3 Energy dispersive X-ray (EDX) spectroscopy

EDX spectroscopy was used to examine the tiny particles (NPs) within a specially designed structure (hybrid nanostructure). Figure 4 shows the EDX results for these NPs. The analysis confirmed that ZnO NPs were pure, as there were no extra peaks in the spectrum. The Au NPs, as expected, only contained Au atoms. Similarly, the EDX spectra of the gold–zinc oxide (Au–ZnO) mixture (in a 9:1 ratio) showed the presence of zinc, oxygen, and Au. The analysis confirmed that the Au–ZnO mixture had the same basic elements as the individual components. Interestingly, the Au peaks were easily visible in the spectrum, while the zinc signal was also strong. This suggests a good distribution of both elements. In all the structures except pure Au, the presence of oxygen confirmed the successful formation of metal oxides. Furthermore, detailed maps obtained using EDX revealed a uniform spread of Au atoms across the ZnO surface. The researchers believe that the uneven distribution of Au on ZnO in another mixture (5:95 ratio) can significantly enhance its ability to break down pollutants using light (photocatalytic activity). This is because the uneven distribution creates numerous areas where Au and ZnO come into close contact, which is beneficial for this process. The specific percentages of each element in the different mixtures are given in Table 2 [23,24].

Figure 4 (a–d) EDX data for ZnO, Au, and Au–ZnO (95:5) and Au–ZnO (90:10) nanocomposites.
Figure 4

(a–d) EDX data for ZnO, Au, and Au–ZnO (95:5) and Au–ZnO (90:10) nanocomposites.

Table 2

Ratios of each of the elements zinc, Au, and oxygen

Sample Element Weight% Atomic%
ZnO O 76.71 89.86
Zn 20.19 13.24
Au Au 100 100
Au–ZnO (95:5) O 32.19 74.16
Zn 64.3 24.5
Au 3.51 1.34
Au–ZnO (90:10) O 34.32 72.5
Zn 60.41 25.2
Au 5.27 2.3

3.4 Transmission electron microscopy (TEM)

The dimensions and morphologies of the synthesized nanomaterials were analyzed using TEM. Figures 5 and 6 display TEM micrographs of the nanomaterials produced for this study, providing a more comprehensive visualization of the particles’ morphology and dimensions.

Figure 5 Average particle size of synthesized Au NPs.
Figure 5

Average particle size of synthesized Au NPs.

Figure 6 (a–d) TEM images of ZnO, Au, and Au–ZnO (95:5) and Au–ZnO (90:10) nanocomposites.
Figure 6

(a–d) TEM images of ZnO, Au, and Au–ZnO (95:5) and Au–ZnO (90:10) nanocomposites.

The TEM images of ZnO NPs demonstrate that the particles have a predominantly hexagonal shape with limited aggregation, aligning with the findings of the FE-SEM investigation. The mean particle size was determined to range from 20 to 200 nm [25].

The TEM images of Au NPs exhibit the presence of spherical Au NPs, characterized by an average particle size of 25 nm Figure 5. This observation aligns with the findings obtained from the FE-SEM analysis. The TEM image provides unambiguous evidence of their predominantly spherical shape, with average particle sizes ranging from 20 to 80 nm [26].

The Au–ZnO (95:5) nanocomposite displays equally distributed Au NPs with effective capping and stabilizing characteristics attributed to the Citrus medica leaf extract.

The TEM images of ZnO doped with Au reveal an increase in particle size, accompanied by noticeable agglomeration and a non-uniform distribution of Au and ZnO (ZnO) NPs. The NPs appear agglomerated with a virtually spherical form, and the average size falls within the range of 25–45 nm.

The TEM images of the Au–ZnO (90:10) nanocomposite clearly show the presence of NPs with various morphologies. Additionally, it indicates substantial aggregation in the anisotropic nanostructure [27].

3.5 Atomic force microscopy (AFM)

The topographic properties of the as-synthesized nanomaterials were investigated using AFM analysis. The 3D image of the Au–ZnO nanocomposite described by the AFM in tapping mode is shown in Figure 7. The topographic features of the as-synthesized nanomaterials are summarized. The average roughness values (R a) of ZnO and Au NPs surfaces were 3.21 and 6.13 nm, respectively. The roughness value increases to 12.13 for ZnO NPs and 26.00 for Au NPs after coupling and doping with Au NPs, respectively. When compared to other ZnO nanostructures, the Au–ZnO (90:10) nanocomposite has a larger surface roughness (105.07 nm), indicating that this sample has a higher surface/volume ratio, which may enhance electron–hole pair formation when light is applied to the surface, The thickness of ZnO and Au NPs is calculated to be 15.12 and 105 nm, respectively, and it increases for Au–ZnO NPs (53.1 nm). The variation in the nanostructure thickness obtained from AFM is almost identical to the variation trend in the grain size. Agglomeration increases as a result of the high concentration of Au NPs, resulting in an increase in the thickness and surface roughness of ZnO nanocomposites. Table 3 summarizes the topographic properties of the as-synthesized nanomaterials. From Table 3, the average roughness values (R a) of surfaces were 23.4 for the Au–ZnO (95:5) nanocomposite. Upon coupling and doping with Au NPs, the roughness increases to 50.9. The variation in the nanostructure thickness obtained from AFM analysis is almost like the variation trend in the grain size, as displayed in Table 3. Furthermore, the heightened roughness of as-produced nanomaterial surfaces is defined by the observed negative values of skewness (R sk), indicating a surface with more deep and steep valleys, as seen. Additionally, a statistical measure known as the kurtosis parameter (R ku) describes the asymmetry and flatness of a surface distribution. All generated nanostructures may be categorized as having spiky surfaces, and R ku3 is one of them [28,29].

Figure 7 (a–h) 3D and 2D images of AFM for Au–ZnO (95:5) and Au–ZnO (90:10) nanocomposites.
Figure 7

(a–h) 3D and 2D images of AFM for Au–ZnO (95:5) and Au–ZnO (90:10) nanocomposites.

Table 3

AFM parameter values of the prepared samples

Amplitude Factors ZnO Au Au–ZnO (95:5) Au–ZnO (90:10)
R a (nm) 3.21 6.13 23.4 25.7
R q (nm) 3.33 8.32 22.1 30.9
R sk (nm) −0.0184 0.0328 −3.19 −3.3
R ku (nm) 1.59 1.6 1.85 1.98
Thickness 12.32 26.00 50.9 105.07

3.6 Surface area analysis (BET)

Based on Figure 8 and the data, the adsorption and desorption of nitrogen follow a Type III isotherm according to the International Union of Pure and Applied Chemistry (IUPAC) classification. This indicates that all the prepared composites exhibit mesoporous characteristics, further confirmed by the H3-type hysteresis loop observed. Notably, the Au–ZnO (90:10) nanocomposite displayed a higher surface roughness attributed to the combined effects of increased pore diameter and smaller particle size [30].

Figure 8 BET of the prepared particles.
Figure 8

BET of the prepared particles.

3.7 UV-visible diffuse reflectance spectroscopy (DRS)

The band gaps of the synthesized nanomaterials were determined using UV-visible DRS. As previously reported, combining ZnO with Au through doping can improve its photocatalytic performance. This enhancement may be attributed to the formation of additional energy levels within the ZnO band gap due to the presence of Au ions. The band gap energy (E g) can be calculated using the following equation:

(2) ( α hv ) 2 = B ( hv − E g ) γ

where α is the absorption coefficient, h is the Planck constant, υ is the frequency of incident photons, and B is a constant representing the band tailing parameter. Eq. 2 displays the diffuse reflectance spectra (DRS) of the synthesized nanomaterials. The direct optical band gap of each material was estimated from the corresponding plot of hυ versus (αhv)2. Figure 2 shows the calculated E g values for ZnO, Au, Au–ZnO (95:5), and Au–nO (90:10) to be 3.28, 2.93, 3.60, and 3.87 eV, respectively. Notably, the absorption edge shifts towards longer wavelengths with increased Au doping in ZnO. These results confirm that doping ZnO with Au NPs enhances its absorption of visible light and narrows its band gap, consistent with the findings reported in previous studies [31,32] (Figures 9 and 10).

Figure 9 UV-Vis absorption spectra of Au, ZnO, Au–ZnO (95:5), and Au–ZnO (90:10).
Figure 9

UV-Vis absorption spectra of Au, ZnO, Au–ZnO (95:5), and Au–ZnO (90:10).

Figure 10 A Tauc plot equation for the nanostructures Au, ZnO, Au–ZnO (95:5), Au–ZnO (90:10).
Figure 10

A Tauc plot equation for the nanostructures Au, ZnO, Au–ZnO (95:5), Au–ZnO (90:10).

3.8 Photocatalytic degradation of RhB dye

Scientists used a special dye called RhB to simulate organic pollutants in the environment. They tested whether light could break down this dye (photodegradation) by shining visible light on it without any additional help (photocatalyst). This did not work very well. Next, they tried adding different materials (photocatalysts) to the dye solution and shining light on it again. This time, the dye broke down more, but still not very efficiently.

Figure 11 shows how long it took to break down the dye using light and tiny, specially made particles (nanomaterials) at a certain concentration. The longer the light shone, the more dye broke down, but the effect slowed down over time. Interestingly, a mixture of Au and ZnO nanoparticles (Au–ZnO) in a specific ratio (90:10) worked much better than other materials tested before. With this mixture, almost all the dye broke down (92.1%) within 2 h of light exposure. In comparison, using plain ZnO as the photocatalyst was much less effective, only breaking down about half the dye [33].

Figure 11 Efficiency of the optical degradation process of the rhodamine dye in the presence of nanomaterials.
Figure 11

Efficiency of the optical degradation process of the rhodamine dye in the presence of nanomaterials.

3.8.1 Effects of the dosage of photocatalyst

The optimal dosage of the photocatalyst was determined through a series of experiments, with the aim of achieving effective absorption of transmitted visible light. The concentration of the Au–ZnO (90:10) nanocomposite was systematically altered within the range of 0.2 to 1.4 g·L−1 under certain fixed conditions. These parameters included a fixed concentration of RhB at 20 ppm, a pH value of 7, an irradiation time of 120 min, and a temperature of 298 K. The efficiency of photodegradation exhibited a significant increase from 78.95 to 99.1%, as the dosage of the photocatalyst was increased from 0.2 to 1.0 g·L−1, respectively, as depicted in Figure 12. The increase in the dosage of the photocatalyst results in a greater number of surface-active sites, which in turn enhances the production of highly reactive radical species responsible for driving the photodegradation reaction. A notable decline in the effectiveness of photodegradation was seen at a concentration of 1.0 g·L−1. This phenomenon can be attributed to the excessive loading of the photocatalyst, resulting in unfavorable light scattering and the creation of an impermeable suspension. The phenomenon of agglomeration, resulting from the interaction between particles, becomes more pronounced as the dosage of the photocatalyst increases. This agglomeration is a significant factor contributing to the reduced light absorption capacity of the photocatalyst. Consequently, for the following investigations, a concentration of 1.0 g·L−1 of the Au–ZnO (90:10) nanocomposite was employed as the photocatalyst [34].

Figure 12 The catalytic activity of various photocatalysts.
Figure 12

The catalytic activity of various photocatalysts.

3.8.2 Effect of initial dye concentration

The concentrations of colors in wastewater effluents released from different phases of dyeing operations exhibit variability, which is influenced by the quantity of dyes utilized during the coloring procedure, as shown in Figure 13. The extent of light penetration in the reaction solution, in order to reach the surface of the photocatalyst, is subject to modification by altering the initial concentration of the dye. Therefore, it is imperative to examine the influence of the initial dye concentration on the efficacy of photodegradation. Figure 13 illustrates the impact of varying concentrations of dye RhB on the effectiveness of photodegradation. The experiment involved adjusting the initial dye concentration from 5 to 25 ppm, utilizing a catalyst consisting of the Au–ZnO (90:10) nanocomposite at a concentration of 1.0 g·L−1. The experiment was conducted under certain conditions, including a pH value of 7, a temperature of 298 K, and a duration of 120 min of visible light exposure. The maximal effectiveness of photodegradation (100%) was attained at a concentration of 5 parts per million (ppm). A correlation has been shown whereby an increase in RhB concentration leads to a decrease in photodegradation efficiency. The reason for this phenomenon is that when the concentration of dye increases, a greater number of dye molecules are adsorbed onto the surface-active sites, so impeding the ability of photons to reach the surface of the photocatalyst. Consequently, the elevation in the dye concentration leads to a decrease in the accessibility of photoactive sites as a result of enhanced physical adsorption of dye molecules onto the surface of the photocatalyst. This, in turn, leads to a reduction in the generation of OH radicals [35].

Figure 13 The effect of dye concentration on the photocatalyst.
Figure 13

The effect of dye concentration on the photocatalyst.

3.8.3 Effect of initial pH

The influence of solution pH on the surface charge properties of the photocatalyst is widely recognized, making it a crucial operational parameter. Consequently, solution pH plays a substantial role in the adsorption and photocatalytic degradation of water pollutants. The impact of solution pH on the photodegradation efficiency of the Au–ZnO (90:10) nanocomposite photocatalyst against RhB dye is illustrated in Figure 14. The increase in pH from 2 to 12 resulted in a corresponding enhancement in the photodegradation efficiency, with values from 76.3% to 99.1%. The results can be explained by the zero-point charges of the Au–ZnO (90:10) nanocomposite (pHzpc 8.47), as depicted in Figure 14. Consequently, it is anticipated that a change in the pH towards an alkaline environment may facilitate an increase in the concentration of hydroxide (OH−) anions within the solution, thereby promoting a more effective generation of hydroxyl (OH) radicals. The primary reactive oxygen species (ROS) responsible for initiating the photodegradation reaction are hydroxyl (OH) radicals. The enhanced effectiveness of RhB dye degradation in alkaline environments can be primarily attributed to the increased generation of ˙OH radicals from the hydroxyl group (OH–) rather than water (H2O). The positive charge on the surface of the Au–ZnO (90:10) nanocomposite at acidic pH levels, caused by functional protonation, leads to competition with positively charged RhB molecules for binding to active sites. As a consequence, the photodegradation efficiency is reduced. At pH values higher than the point of zero charge (pHzpc), the surface of the photocatalyst becomes negatively charged due to the presence of hydroxyl anions. This negative charge facilitates the adsorption of RhB molecules onto the surface of the Au–ZnO (90:10) nanocomposite through electrostatic attraction forces. As a result, there is a significant enhancement in the efficiency of photodegradation [36].

Figure 14 Effect of pH solution on the degradation of RhB dye.
Figure 14

Effect of pH solution on the degradation of RhB dye.

3.9 Kinetic study

The present study investigated the photocatalytic performance of a nanocomposite consisting of Au–ZnO (90:10) under visible light irradiation. The RhB dye was employed as an organic pollutant for analysis. The UV/Vis absorption spectra of RhB solutions over the Au–ZnO (90:10) nanocomposite under visible light exposure are depicted in Figure 15. The spectra are presented as a function of irradiation time. The findings indicated that there was an inverse relationship between the duration of UV exposure and the magnitude of UV-Vis absorption spectra for RhB. The observed decrease in absorbance can be attributed to a reduction in concentration, potentially resulting from the degradation of the dye chromogen. This suggests that the catalyst effectively breaks down the conjugated xanthene ring in RhB. No new absorption peaks were seen after 50 min of irradiation, suggesting that the dye underwent full mineralization. Figure 15 illustrates the utilization of the first-order kinetic model, as represented by Eq. 3, for the investigation of the photodegradation process of the Au–ZnO (90:10) nanocomposite photocatalyst. The relationship between the natural logarithm of the ratio C 0/C and the duration of irradiation is depicted in Figure 15. This graph provides evidence in favor of the hypothesis that the degradation of dye follows a kinetic model known as pseudo-first-order kinetics [37,38]. The RhB photodegradation process on the Au–ZnO (90:10) nanocomposite photocatalysts was seen to exhibit a pseudo-first-order kinetic constant of 1.67 × 10–3 s−1.

(3) ln ln C 0 C t = k × t

Figure 15 Effect on the absorption spectrum of RhB dye at a maximum wavelength.
Figure 15

Effect on the absorption spectrum of RhB dye at a maximum wavelength.

3.10 Recycling of photocatalyst

The study conducted a series of degradation experiments on RhB using a five-cycle approach. The experiments were conducted under consistent reaction conditions, with the only variation being the replacement of the RhB dye solution after each cycle. No washing or drying treatments were applied to the catalyst particles between successive runs. The objective of these experiments was to examine the photostability and reusability of the Au-ZnO (90:10) nanocomposite, which was synthesized using a green method. Figure 16 illustrates that the catalytic activity of the Au–ZnO nanocomposite has had a marginal drop, but with a modest decline observed after three cycles. Consequently, the nanocomposite composed of Au–ZnO (90:10) exhibits remarkable photostability, as evidenced by the high destruction efficiency of RhB of 99.1%, 91.1%, and 87.4% during the initial, subsequent, and third cycles, respectively, following a 50-min irradiation period. Nevertheless, during four successive cycles, the catalyst photocatalytic activity remains above 82.4% of its initial value. This observation provides evidence for the favorable photostability of the Au–ZnO (90:10) nanocomposite and lends credence to the notion that the photocatalyst can be reused for the degradation of RhB in an aqueous solution. Following a mere five experimental iterations, the photodegradation efficacy exhibited a decline, reaching a value of 74.9%. The decrease in photodegradation efficiency can be attributed to multiple factors. First, the active sites of the catalyst become occupied by dye molecules and reaction intermediates. This results in a decrease in the available catalytic surface area, which in turn hinders the photodegradation process. Additionally, at high concentrations, the particles of the catalyst tend to agglomerate, further reducing the effective surface area for catalysis. Furthermore, the adsorptive occupation of active sites by various substances can lead to the blocking of these sites, thereby lowering the overall photodegradation efficiency.

Figure 16 Reuse of the catalyst.
Figure 16

Reuse of the catalyst.

3.11 Effect of radical scavengers

The two main ROS, OH˙ and O 2 ˙ , are known to contribute significantly to the surface reaction. The hydroxyl radical is a non-selective, extremely powerful oxidant that causes partial or total mineralization of a variety of organic compounds. These species are the most important in the decolorization process, and raising their numbers increases the pace of decolorization. Different scavengers can be used to determine the number of these species and their effects. Several scavengers were utilized in this investigation, including para-benzoquinone for O 2 ˙ . For both h+ and OH˙, potassium iodide (KI) and tert-butanol are used, respectively. As exhibited in Figure 17, the RhB decolorization efficiency is 99% without scavengers after 120 min of irradiation. The degradation efficiency was reduced to 32% under the same circumstances when tert-butanol was added and to 61% when para-benzoquinone was added. Because the iodide ion is a powerful scavenger that reacts with the valence band hole and adsorbed OH˙ radicals, the addition of KI, on the other hand, caused a 17% reduction in the degrading efficiency. The major species are hydroxyl radicals, while the second species is O 2 ˙ , according to these investigations. All tests used a catalyst concentration of 1 g·L−1, a dye concentration of 15 ppm, a pH of 9, a scavenger, and a temperature of 25°C [39].

Figure 17 The absorption spectrum of RhB at a maximum wavelength of 553 nm with time.
Figure 17

The absorption spectrum of RhB at a maximum wavelength of 553 nm with time.

3.12 Mechanism for photodegradation of RhB

Photocatalysis involves three main processes: charge carrier separation, migration, and surface redox reactions. Applications of bare ZnO are limited due to its wide band gap (3.3 eV), resulting in poor charge separation and low visible light absorption [40,41,42]. Doping or decorating ZnO with noble metals like Au can enhance its photoactivity [43,44].

When exposed to visible light, the Au–ZnO catalyst generates electron–hole pairs. Au acts as an electron sink, preventing recombination due to its lower conduction band edge compared to ZnO [45,46]. Photogenerated electrons move from Au to ZnO, while holes move from ZnO to Au. These charge carriers then participate in redox reactions at the surface [47,48,49].

Electrons in the conduction band can reduce adsorbed oxygen (O2) to superoxide radicals (O2−), while holes in the valence band can oxidize hydroxyl ions (OH−) to hydroxyl radicals (OH−). These highly reactive radicals degrade organic pollutants into harmless species like CO2 and H2O [50,51,52].

Understanding the dominant reactive species responsible for RhB degradation over Au–ZnO is crucial [53,54]. During the photodegradation process, scavengers like tert-butanol (OH trap), potassium iodide (OH and h+ trap), and para-benzoquinone (O2 trap) were added to suppress specific reactive species.

The inclusion of tert-butanol and para-benzoquinone had minimal impact on RhB degradation, indicating that O2− radicals play a minor role. However, potassium iodide significantly reduced RhB degradation, suggesting that both holes (h+) and hydroxyl radicals (OH−) are critical contributors [49,55]. Photodegradation efficiency follows the order: KI > tert-butanol > THF, confirming that h+ and OH− are the main reactive species responsible for RhB degradation under visible light on Au–ZnO:

(4) ZnO + h ν → ZnO ( h vB + + e CB − )

(5) O 2 + e CB − → ˙ O 2 −

(6) OH S − + h VB + → ˙ OH

(7) ˙ O 2 − + RhB → Dye degradation

(8) ˙ OH + RhB → Dye degradation

(9) RhB + h VB + → Dye degradation

4 Conclusions

Citrus medica leaf extract was successfully used to prepare various nanomaterials, including ZnO, Au, and Au–ZnO composites (95:5 and 90:10), for photodegradation applications in water purification. Characterization techniques like XRD, FE-SEM, TEM, EDX, and AFM confirmed the structural, morphological, optical, elemental, topographical, and chemical properties of these nanomaterials.

Decoration of ZnO with Au shifted its absorption peak towards the visible light range, leading to significantly improved photodegradation efficiency. The Au–ZnO (90:10) composite achieved the highest efficiency, reaching 99.1% compared to 52.32% for bare ZnO. Under optimal conditions (pH 12, 50 min irradiation), this composite proved to be a viable photocatalyst for degrading RhB dye under visible light.

Experiments confirmed the effectiveness of the nanocatalysts in removing RhB dye from water under visible light. The optimal conditions for Au–ZnO (90:10) were 1.0 g·L−1 catalyst, 20 ppm RhB solution, pH 10, and 50 min irradiation, achieving 99% photodegradation.

Enhanced photodegradation efficiency in Au–ZnO (90:10) was attributed to photogenerated holes and hydroxyl radicals. Reaction kinetics and reusability of the best catalyst were also studied, confirming its sustained effectiveness over multiple cycles.

In conclusion, this study demonstrates the successful synthesis of Au–ZnO nanocomposites using Citrus medica extract and their potential as promising photocatalysts for organic dye degradation and water.

,

Acknowledgments

The authors extend their appreciation to the Deanship of Research and Graduate Studies at King Khalid University for funding this work through Large Research Project under grant number RGP2/411/45.

  1. Funding information: The authors extend their appreciation to the Deanship of Research and Graduate Studies at King Khalid University for funding this work through Large Research Project under grant number RGP2/411/45.

  2. Author contributions: Conceptualization: Tiba Ibrahim, Luma Hakim Ali, Wisam Aqeel Muslim, Karrar Hazim Salem, Kahtan A. Mohammed, Rahman S. Zabibah, Mohammed Ayad Alkhafaji, Zahraa Falah Khudair, and Shubham Sharma; formal analysis: Tiba Ibrahim, Luma Hakim Ali, Wisam Aqeel Muslim, Karrar Hazim Salem, Kahtan A. Mohammed, Rahman S. Zabibah, Mohammed Ayad Alkhafaji, Zahraa Falah Khudair, Shubham Sharma, Emad Makki, and Mohamed Abbas; investigation: Tiba Ibrahim, Luma Hakim Ali, Wisam Aqeel Muslim, Karrar Hazim Salem, Kahtan A. Mohammed, Rahman S. Zabibah, Mohammed Ayad Alkhafaji, Zahraa Falah Khudair, and Shubham Sharma; writing – original draft preparation: Tiba Ibrahim, Luma Hakim Ali, Wisam Aqeel Muslim, Karrar Hazim Salem, Kahtan A. Mohammed, Rahman S. Zabibah, Mohammed Ayad Alkhafaji, Zahraa Falah Khudair, and Shubham Sharma; writing – review and editing: Shubham Sharma, Emad Makki, and Mohamed Abbas; project administration: Shubham Sharma, Emad Makki, Mohamed Abbas; Resources, Emad Makki, Mohamed Abbas; Visualization, Emad Makki, and Mohamed Abbas; funding acquisition: Shubham Sharma, Emad Makki, and Mohamed Abbas. All authors have read and agreed to the published version of the manuscript. All authors have read and agreed to the published version of the manuscript.

  3. Conflict of interest: Authors state no conflict of interest.

  4. Data availability statement: All data generated or analysed during this study are included in this published article.

References

[1] Awasthi G, Nagar V, Mandzhieva S, Minkina T, Sankhla MS, Pandit PP, et al. Sustainable amelioration of heavy metals in soil ecosystem: Existing developments to emerging trends. Minerals. 2022;12(1):85.10.3390/min12010085Search in Google Scholar

[2] Blunt JW, Carroll AR, Copp BR, Davis RA, Keyzers RA, Prinsep MR. Marine natural products. Nat Prod Rep. 2018;35(1):8–53.10.1039/C7NP00052ASearch in Google Scholar PubMed

[3] Fardood ST, Moradnia F, Forootan R, Abbassi R, Jalalifar S, Ramazani A, et al. Facile green synthesis, characterization and visible light photocatalytic activity of MgFe2O4@ CoCr2O4 magnetic nanocomposite. J Photochem Photobiol A: Chem. 2022;423:113621.10.1016/j.jphotochem.2021.113621Search in Google Scholar

[4] Behera M, Nayak J, Banerjee S, Chakrabortty S, Tripathy SK. A review on the treatment of textile industry waste effluents towards the development of efficient mitigation strategy: An integrated system design approach. J Environ Chem Eng. 2021;9(4):105277.10.1016/j.jece.2021.105277Search in Google Scholar

[5] Taoufik N, Boumya W, Achak M, Sillanpää M, Barka N. Comparative overview of advanced oxidation processes and biological approaches for the removal pharmaceuticals. J Environ Manag. 2021;288:112404.10.1016/j.jenvman.2021.112404Search in Google Scholar PubMed

[6] Alshamsi HAH, Jaffer AA. Microwave-assisted synthesis of ZnO nanoparticles and its photocatalytic activity in degradation of Rhodamine B dye. Int J Pharm Res. 2020;12(1):201–10.10.31838/ijpr/2020.12.01.040Search in Google Scholar

[7] Kumar R, Kumar K, Thakur N, Chauhan MS. Harnessing microwaves for the Biosynthesis of CuO-Co3O4 NCs: a dual study on photocatalytic process and antibacterial effectiveness. Int J Environ Anal Chem. 2023;345:1–20.10.1080/03067319.2023.2289172Search in Google Scholar

[8] Goktas S, Goktas A. A comparative study on recent progress in efficient ZnO based nanocomposite and heterojunction photocatalysts: A review. J Alloy Compd. 2021;863:158734.10.1016/j.jallcom.2021.158734Search in Google Scholar

[9] Sanakousar FM, Vidyasagar CC, Jiménez-Pérez VM, Prakash K. Recent progress on visible-light-driven metal and non-metal doped ZnO nanostructures for photocatalytic degradation of organic pollutants. Mater Sci Semicond Process. 2022;140:106390.10.1016/j.mssp.2021.106390Search in Google Scholar

[10] Nejati K, Dadashpour M, Gharibi T, Mellatyar H, Akbarzadeh A. Biomedical applications of functionalized gold nanoparticles: a review. J Clust Sci. 2021;33:1–16.10.1007/s10876-020-01955-9Search in Google Scholar

[11] Rashid TM, Nayef UM, Jabir MS, Mutlak FA. Study of optical and morphological properties for Au-ZnO nanocomposite prepared by Laser ablation in liquid. J Phys: Conf Ser. 2021;1795:01204110.1088/1742-6596/1795/1/012041Search in Google Scholar

[12] Qiu Y, Pan Z, Chen H, Ye D, Guo L, Fan Z, et al. Current progress in developing metal oxide nanoarrays-based photoanodes for photoelectrochemical water splitting. Sci Bull. 2019;64(18):1348–80.10.1016/j.scib.2019.07.017Search in Google Scholar PubMed

[13] Pugazhenthiran N, Murugesan S, Sathishkumar P, Suresh S, Karthick Kumar S, Selvaraj M, et al. Silver nanoparticles modified Zno nanocatalysts for effective degradation of ceftiofur sodium under white light illumination. Chemosphere. 2023;313:137515.10.1016/j.chemosphere.2022.137515Search in Google Scholar PubMed

[14] Kanakkillam SS, Krishnan B, Peláez RFC, Martinez JAA, Avellaneda DA, Shaji S. Hybrid nanostructures of Ag/Au-ZnO synthesized by pulsed laser ablation/irradiation in liquid. Surf Interfaces. 2021;27:101561.10.1016/j.surfin.2021.101561Search in Google Scholar

[15] Hazim K, Hameed GF, Mohamed L. Environmentally friendly synthesis, antibacterial activity, and photocatalytic performance of AG nanoparticles made from Leucaena Leucocephala leaves extract. Pak J Med Health Sci. 2022;16(04):427.10.53350/pjmhs22164427Search in Google Scholar

[16] Li Y, Liu T, Feng S, Yang W, Zhu Y, Zhao Y, et al. Au/CdS Core-shell sensitized actinomorphic flower-like ZnO nanorods for enhanced photocatalytic water splitting performance. Nanomaterials. 2021;11(1):233.10.3390/nano11010233Search in Google Scholar PubMed PubMed Central

[17] Peychev B, Vasileva P. Novel starch-mediated synthesis of Au/ZnO nanocrystals and their photocatalytic properties. Heliyon. 2021;7(6):e07402.10.1016/j.heliyon.2021.e07402Search in Google Scholar PubMed PubMed Central

[18] Hazim K, Hamza Z, Mohamed L. Eco-friendly synthesis, antibacterial activity, and photocatalytic performance of Zno nanoparticles synthesized via leaves extract of Paraserianthes lophantha. Pak J Med Health Sci. 2022;16(03):581.10.53350/pjmhs22163581Search in Google Scholar

[19] Yu S, Zhang H, Chen C, Lin C. Investigation of humidity sensor based on Au modified ZnO nanosheets via hydrothermal method and first principle. Sens Actuators B: Chem. 2019;287:526–34.10.1016/j.snb.2019.02.089Search in Google Scholar

[20] Taghavi Fardood S, Moradnia F, Moradi S, Forootan R, Yekke Zare F, Heidari M. Eco-friendly synthesis and characterization of α-Fe2O3 nanoparticles and study of their photocatalytic activity for degradation of Congo red dye. Nanochem Res. 2019;4(2):140–7.Search in Google Scholar

[21] Moradnia F, Fardood ST, Ramazani A, Gupta VK. Green synthesis of recyclable MgFeCrO4 spinel nanoparticles for rapid photodegradation of direct black 122 dye. J Photochem Photobiol A: Chem. 2020;392:112433.10.1016/j.jphotochem.2020.112433Search in Google Scholar

[22] Xu H, Wei Z, Verpoort F, Hu J, Zhuiykov S. Nanoscale Au-ZnO heterostructure developed by atomic layer deposition towards amperometric H2O2 detection. Nanoscale Res Lett. 2020;15(1):1–14.10.1186/s11671-020-3273-7Search in Google Scholar PubMed PubMed Central

[23] Nasiri Khalil Abad S, Mozammel M, Moghaddam J, Mostafaei A, Chmielus M. Highly porous, flexible and robust cellulose acetate/Au/ZnO as a hybrid photocatalyst. Appl Surf Sci. 2020;526:146237.10.1016/j.apsusc.2020.146237Search in Google Scholar

[24] Awais A, Arsalan M, Qiao X, Yahui W, Sheng Q, Yue T, et al. Facial synthesis of highly efficient non-enzymatic glucose sensor based on vertically aligned Au-ZnO NRs. J Electroanal Chem. 2021;895:115424.10.1016/j.jelechem.2021.115424Search in Google Scholar

[25] Ahmad M, Rehman W, Khan MM, Qureshi MT, Gul A, Haq S, et al. Phytogenic fabrication of ZnO and gold decorated ZnO nanoparticles for photocatalytic degradation of Rhodamine B. J Environ Chem Eng. 2021;9(1):104725.10.1016/j.jece.2020.104725Search in Google Scholar

[26] Ali SG, Ansari MA, Alzohairy MA, Alomary MN, Jalal M, AlYahya S, et al. Effect of biosynthesized ZnO nanoparticles on multi-drug resistant Pseudomonas aeruginosa. Antibiotics. 2020;9(5):260.10.3390/antibiotics9050260Search in Google Scholar PubMed PubMed Central

[27] Wang Y, Zhu G, Li M, Singh R, Marques C, Min R, et al. Water pollutants p-cresol detection based on Au-ZnO nanoparticles modified tapered optical fiber. IEEE Trans NanoBiosci. 2021;20(3):377–84.10.1109/TNB.2021.3082856Search in Google Scholar PubMed

[28] Biswas R, Banerjee B, Saha M, Ahmed I, Mete S, Patil RA, et al. Green approach for the fabrication of Au/ZnO nanoflowers: A catalytic aspect. J Phys Chem C. 2021;125(12):6619–31.10.1021/acs.jpcc.0c10149Search in Google Scholar

[29] Kocyigit A, Orak İ, Turut A. Temperature dependent dielectric properties of Au/ZnO/n-Si heterojuntion. Mater Res Express. 2018;5(3):035906.10.1088/2053-1591/aab2e3Search in Google Scholar

[30] Chen S, Abdel-Mageed AM, Hauble A, Ishida T, Murayama T, Parlinska-Wojtan M, et al. Performance of Au/ZnO catalysts in CO2 reduction to methanol: Varying the Au loading/Au particle size. Appl Catal A: Gen. 2021;624:118318.10.1016/j.apcata.2021.118318Search in Google Scholar

[31] Chandio AA, Jiang Y, Akram W, Adeel S, Irfan M, Jan I. Addressing the effect of climate change in the framework of financial and technological development on cereal production in Pakistan. J Clean Prod. 2021;288:125637.10.1016/j.jclepro.2020.125637Search in Google Scholar

[32] Herrmann WA. 50 Years of passion for organometallic chemistry. J Organomet Chem. 2023;1000:122815.10.1016/j.jorganchem.2023.122815Search in Google Scholar

[33] Dey A, Sarkar SK. Room temperature ZnO and Au-ZnO quantum dots thin film gas sensor fabrication for detecting of volatile organic compound gases. IEEE Sens J. 2020;20(21):12602–9.10.1109/JSEN.2020.3002967Search in Google Scholar

[34] Verma S, Tirumala Rao B, Singh R, Kaul R. Photocatalytic degradation kinetics of cationic and anionic dyes using Au–ZnO nanorods: role of pH for selective and simultaneous degradation of binary dye mixtures. Ceram Int. 2021;47(24):34751–64.10.1016/j.ceramint.2021.09.014Search in Google Scholar

[35] Mehmood M, Ali SM, Ramay SM, Alkhuraiji TS. Au/ZnO hybrid nanocomposites and their optical and photocatalytic properties. Appl Phys A. 2020;126(9):1–14.10.1007/s00339-020-03909-4Search in Google Scholar

[36] Singh J, Soni R. Controlled synthesis of CuO decorated defect enriched ZnO nanoflakes for improved sunlight-induced photocatalytic degradation of organic pollutants. Appl Surf Sci. 2020;521:146420.10.1016/j.apsusc.2020.146420Search in Google Scholar

[37] Choudhary MK, Kataria J, Sharma S. Novel green biomimetic approach for preparation of highly stable Au-ZnO heterojunctions with enhanced photocatalytic activity. ACS Appl Nano Mater. 2018;1(4):1870–8.10.1021/acsanm.8b00272Search in Google Scholar

[38] De Corrado JM, Fernando JFS, Shortell MP, Poad BLJ, Blanksby SJ, Waclawik ER. ZnO colloid crystal facet-type determines both Au photodeposition and photocatalytic activity. ACS Appl Nano Mater. 2019;2(12):7856–69.10.1021/acsanm.9b01864Search in Google Scholar

[39] Dedova T, Acik IO, Chen Z, Katerski A, Balmassov K, Gromyko I, et al. Enhanced photocatalytic activity of ZnO nanorods by surface treatment with HAuCl4: Synergic effects through an electron scavenging, plasmon resonance and surface hydroxylation. Mater Chem Phys. 2020;245:122767.10.1016/j.matchemphys.2020.122767Search in Google Scholar

[40] Taghavi Fardood S, Moradnia F, Heidarzadeh S, Naghipour A. Green synthesis, characterization, photocatalytic and antibacterial activities of copper oxide nanoparticles. Nanochem Res. 2023;8(2):134–40. 10.22036/ncr.2023.02.006.Search in Google Scholar

[41] Taghavi Fardood S, Ramazani A, Asiabi P, Joo S. A novel green synthesis of copper oxide nanoparticles using a henna extract powder. J Struct Chem. 2018;59:1737–43. 10.1134/S0022476618070302.Search in Google Scholar

[42] Moradnia F, Taghavi Fardood S, Ramazani A, Osali S, Abdolmaleki I. Green sol–gel synthesis of CoMnCrO4 spinel nanoparticles and their photocatalytic application. Micro Nano Lett. 2020;15(10):674–7. 10.1049/mnl.2020.0189.Search in Google Scholar

[43] Taghavi Fardood S, Ramazani A, Golfar Z, Joo SW. Green synthesis using tragacanth gum and characterization of Ni–Cu–Zn ferrite nanoparticles as a magnetically separable catalyst for the synthesis of hexabenzylhexaazaisowurtzitane under ultrasonic irradiation. J Struct Chem. 2018;59:1730–6. 10.1134/S0022476618070296.Search in Google Scholar

[44] Fardood ST, Ramazani A. Black tea extract mediated green synthesis of copper oxide nanoparticles. J Appl Chem Res. 2018;12(2):8–15. https://dorl.net/dor/20.1001.1.20083815.2018.12.2.1.1.Search in Google Scholar

[45] Moradnia F, Fardood ST, Ramazani A, Min BK, Joo SW, Varma RS. Magnetic Mg0. 5Zn0. 5FeMnO4 nanoparticles: green sol-gel synthesis, characterization, and photocatalytic applications. J Clean Prod. 2021;288:125632. 10.1016/j.jclepro.2020.125632.Search in Google Scholar

[46] Kiani MT, Ramazani A, Taghavi Fardood S. Green synthesis and characterization of Ni0. 25Zn0. 75Fe2O4 magnetic nanoparticles and study of their photocatalytic activity in the degradation of aniline. Appl Organomet Chem. 2023;37(4):e7053. 10.1002/aoc.7053.Search in Google Scholar

[47] Srour A, Basma H, Noureldeen S, Malaeb W, Awad R. ESR Investigations of (BaSnO3)x/(Cu, Tl) 1223 composite in the normal and superconducting state. Phase Transit. 2021;94(3–4):199–209. 10.1080/01411594.2021.1931205.Search in Google Scholar

[48] Issa CA. Introduction to multifunctional epoxy composites. In: Hameed N, Capricho JC, Salim N, Thomas S, editors. Multifunctional epoxy resins. Engineering materials. Singapore: Springer; 2023; p. 1–13. 10.1007/978-981-19-6038-3_1.Search in Google Scholar

[49] Daoura O, El Hassan N, Boutros M, Casale S, Massiani P, Launay F. Effect of impregnation with ammonia vs silica support textural properties on Ni nanoparticle catalysts for dry reforming of methane. ACS Appl Nano Mater. 2022;5(12):18048–59. 10.1021/acsanm.2c03995.Search in Google Scholar

[50] Kamar A, Srour A, Roumié M, Malaeb W, Awad R, Khalaf A. Comparative study of structural and superconducting properties of (Cu0.5Tl0.5)Ba2Ca2Cu3O10-δ phase substituted by copper fluoride and thallium fluoride. Appl Phys A. 2021;127(8):579. 10.1007/s00339-021-04707-2.Search in Google Scholar

[51] Roukos R, Romanos J, Abou Dargham S, Chaumont D. Evidence of a stable tetragonal (P4bm) phase in rhombohedral (R3c) complex perovskite (Na1/2Bi1/2)1−xCaxTiO3 lead-free piezoelectric materials. Mater Sci Eng B: Solid-State Mater Adv Technol. 2023;288:1–12. 10.1016/j.mseb.2022.116196.Search in Google Scholar

[52] Nasser A, Srour A, El Ghouch N, Malaeb W, Al-Oweini R, Awad R. Investigation of the physical properties of (Cu0.5Tl0.5)Ba2Ca2Cu3O10-δ impregnated with mono cobalt(II)-substituted undecatungstosilicate nanoparticles. Appl Phys A: Mater Sci Process. 2020;126(12):1–15. 10.1007/s00339-020-04083-3.Search in Google Scholar

[53] Ghanem T, Vincendeau T, Marqués PS, Habibi AH, Abidi S, Yassin A, et al. Synthesis of push-pull triarylamine dyes containing 5,6-difluoro-2,1,3-benzothiadiazole units by direct arylation and their evaluation as active material for organic photovoltaics. Mater Adv. 2021;2(22):7456–62. 10.1039/d1ma00798j.Search in Google Scholar

[54] Kamar A, Srour A, Roumié M, Malaeb W, Awad R, Khalaf A. Comparative study of structural and superconducting properties of (Cu0.5Tl0.5)Ba2Ca2Cu3O10-δ phase substituted by copper fluoride and thallium fluoride. Appl Phys A: Mater Sci Process. 2021;127:8. 10.1007/s00339-021-04707-2.Search in Google Scholar

[55] Zhang T, Guérin D, Alibart F, Troadec D, Hourlier D, Patriarche G, et al. Physical mechanisms involved in the formation and operation of memory devices based on a monolayer of gold nanoparticle-polythiophene hybrid materials. Nanoscale Adv. 2019;1(7):2718–26. 10.1039/c9na00285e.Search in Google Scholar PubMed PubMed Central

Received: 2023-10-01
Accepted: 2024-02-28
Published Online: 2024-05-15

© 2024 the author(s), published by De Gruyter

This work is licensed under the Creative Commons Attribution 4.0 International License.

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  11. Insight into heating method and Mozafari method as green processing techniques for the synthesis of micro- and nano-drug carriers
  12. Silicotungstic acid supported on Bi-based MOF-derived metal oxide for photodegradation of organic dyes
  13. Synthesis and characterization of capsaicin nanoparticles: An attempt to enhance its bioavailability and pharmacological actions
  14. Synthesis of Lawsonia inermis-encased silver–copper bimetallic nanoparticles with antioxidant, antibacterial, and cytotoxic activity
  15. Facile, polyherbal drug-mediated green synthesis of CuO nanoparticles and their potent biological applications
  16. Zinc oxide-manganese oxide/carboxymethyl cellulose-folic acid-sesamol hybrid nanomaterials: A molecularly targeted strategy for advanced triple-negative breast cancer therapy
  17. Exploring the antimicrobial potential of biogenically synthesized graphene oxide nanoparticles against targeted bacterial and fungal pathogens
  18. Biofabrication of silver nanoparticles using Uncaria tomentosa L.: Insight into characterization, antibacterial activities combined with antibiotics, and effect on Triticum aestivum germination
  19. Membrane distillation of synthetic urine for use in space structural habitat systems
  20. Investigation on mechanical properties of the green synthesis bamboo fiber/eggshell/coconut shell powder-based hybrid biocomposites under NaOH conditions
  21. Green synthesis of magnesium oxide nanoparticles using endophytic fungal strain to improve the growth, metabolic activities, yield traits, and phenolic compounds content of Nigella sativa L.
  22. Estimation of greenhouse gas emissions from rice and annual upland crops in Red River Delta of Vietnam using the denitrification–decomposition model
  23. Synthesis of humic acid with the obtaining of potassium humate based on coal waste from the Lenger deposit, Kazakhstan
  24. Ascorbic acid-mediated selenium nanoparticles as potential antihyperuricemic, antioxidant, anticoagulant, and thrombolytic agents
  25. Green synthesis of silver nanoparticles using Illicium verum extract: Optimization and characterization for biomedical applications
  26. Antibacterial and dynamical behaviour of silicon nanoparticles influenced sustainable waste flax fibre-reinforced epoxy composite for biomedical application
  27. Optimising coagulation/flocculation using response surface methodology and application of floc in biofertilisation
  28. Green synthesis and multifaceted characterization of iron oxide nanoparticles derived from Senna bicapsularis for enhanced in vitro and in vivo biological investigation
  29. Potent antibacterial nanocomposites from okra mucilage/chitosan/silver nanoparticles for multidrug-resistant Salmonella Typhimurium eradication
  30. Trachyspermum copticum aqueous seed extract-derived silver nanoparticles: Exploration of their structural characterization and comparative antibacterial performance against gram-positive and gram-negative bacteria
  31. Microwave-assisted ultrafine silver nanoparticle synthesis using Mitragyna speciosa for antimalarial applications
  32. Green synthesis and characterisation of spherical structure Ag/Fe2O3/TiO2 nanocomposite using acacia in the presence of neem and tulsi oils
  33. Green quantitative methods for linagliptin and empagliflozin in dosage forms
  34. Enhancement efficacy of omeprazole by conjugation with silver nanoparticles as a urease inhibitor
  35. Residual, sequential extraction, and ecological risk assessment of some metals in ash from municipal solid waste incineration, Vietnam
  36. Green synthesis of ZnO nanoparticles using the mangosteen (Garcinia mangostana L.) leaf extract: Comparative preliminary in vitro antibacterial study
  37. Simultaneous determination of lesinurad and febuxostat in commercial fixed-dose combinations using a greener normal-phase HPTLC method
  38. A greener RP-HPLC method for quaternary estimation of caffeine, paracetamol, levocetirizine, and phenylephrine acquiring AQbD with stability studies
  39. Optimization of biomass durian peel as a heterogeneous catalyst in biodiesel production using microwave irradiation
  40. Thermal treatment impact on the evolution of active phases in layered double hydroxide-based ZnCr photocatalysts: Photodegradation and antibacterial performance
  41. Preparation of silymarin-loaded zein polysaccharide core–shell nanostructures and evaluation of their biological potentials
  42. Preparation and characterization of composite-modified PA6 fiber for spectral heating and heat storage applications
  43. Preparation and electrocatalytic oxygen evolution of bimetallic phosphates (NiFe)2P/NF
  44. Rod-shaped Mo(vi) trichalcogenide–Mo(vi) oxide decorated on poly(1-H pyrrole) as a promising nanocomposite photoelectrode for green hydrogen generation from sewage water with high efficiency
  45. Green synthesis and studies on citrus medica leaf extract-mediated Au–ZnO nanocomposites: A sustainable approach for efficient photocatalytic degradation of rhodamine B dye in aqueous media
  46. Cellulosic materials for the removal of ciprofloxacin from aqueous environments
  47. The analytical assessment of metal contamination in industrial soils of Saudi Arabia using the inductively coupled plasma technology
  48. The effect of modified oily sludge on the slurry ability and combustion performance of coal water slurry
  49. Eggshell waste transformation to calcium chloride anhydride as food-grade additive and eggshell membranes as enzyme immobilization carrier
  50. Synthesis of EPAN and applications in the encapsulation of potassium humate
  51. Biosynthesis and characterization of silver nanoparticles from Cedrela toona leaf extracts: An exploration into their antibacterial, anticancer, and antioxidant potential
  52. Enhancing mechanical and rheological properties of HDPE films through annealing for eco-friendly agricultural applications
  53. Immobilisation of catalase purified from mushroom (Hydnum repandum) onto glutaraldehyde-activated chitosan and characterisation: Its application for the removal of hydrogen peroxide from artificial wastewater
  54. Sodium titanium oxide/zinc oxide (STO/ZnO) photocomposites for efficient dye degradation applications
  55. Effect of ex situ, eco-friendly ZnONPs incorporating green synthesised Moringa oleifera leaf extract in enhancing biochemical and molecular aspects of Vicia faba L. under salt stress
  56. Biosynthesis and characterization of selenium and silver nanoparticles using Trichoderma viride filtrate and their impact on Culex pipiens
  57. Photocatalytic degradation of organic dyes and biological potentials of biogenic zinc oxide nanoparticles synthesized using the polar extract of Cyperus scariosus R.Br. (Cyperaceae)
  58. Assessment of antiproliferative activity of green-synthesized nickel oxide nanoparticles against glioblastoma cells using Terminalia chebula
  59. Chlorine-free synthesis of phosphinic derivatives by change in the P-function
  60. Anticancer, antioxidant, and antimicrobial activities of nanoemulsions based on water-in-olive oil and loaded on biogenic silver nanoparticles
  61. Study and mechanism of formation of phosphorus production waste in Kazakhstan
  62. Synthesis and stabilization of anatase form of biomimetic TiO2 nanoparticles for enhancing anti-tumor potential
  63. Microwave-supported one-pot reaction for the synthesis of 5-alkyl/arylidene-2-(morpholin/thiomorpholin-4-yl)-1,3-thiazol-4(5H)-one derivatives over MgO solid base
  64. Screening the phytochemicals in Perilla leaves and phytosynthesis of bioactive silver nanoparticles for potential antioxidant and wound-healing application
  65. Graphene oxide/chitosan/manganese/folic acid-brucine functionalized nanocomposites show anticancer activity against liver cancer cells
  66. Nature of serpentinite interactions with low-concentration sulfuric acid solutions
  67. Multi-objective statistical optimisation utilising response surface methodology to predict engine performance using biofuels from waste plastic oil in CRDi engines
  68. Microwave-assisted extraction of acetosolv lignin from sugarcane bagasse and electrospinning of lignin/PEO nanofibres for carbon fibre production
  69. Biosynthesis, characterization, and investigation of cytotoxic activities of selenium nanoparticles utilizing Limosilactobacillus fermentum
  70. Highly photocatalytic materials based on the decoration of poly(O-chloroaniline) with molybdenum trichalcogenide oxide for green hydrogen generation from Red Sea water
  71. Highly efficient oil–water separation using superhydrophobic cellulose aerogels derived from corn straw
  72. Beta-cyclodextrin–Phyllanthus emblica emulsion for zinc oxide nanoparticles: Characteristics and photocatalysis
  73. Assessment of antimicrobial activity and methyl orange dye removal by Klebsiella pneumoniae-mediated silver nanoparticles
  74. Influential eradication of resistant Salmonella Typhimurium using bioactive nanocomposites from chitosan and radish seed-synthesized nanoselenium
  75. Antimicrobial activities and neuroprotective potential for Alzheimer’s disease of pure, Mn, Co, and Al-doped ZnO ultra-small nanoparticles
  76. Green synthesis of silver nanoparticles from Bauhinia variegata and their biological applications
  77. Synthesis and optimization of long-chain fatty acids via the oxidation of long-chain fatty alcohols
  78. Eminent Red Sea water hydrogen generation via a Pb(ii)-iodide/poly(1H-pyrrole) nanocomposite photocathode
  79. Green synthesis and effective genistein production by fungal β-glucosidase immobilized on Al2O3 nanocrystals synthesized in Cajanus cajan L. (Millsp.) leaf extracts
  80. Green stability-indicating RP-HPTLC technique for determining croconazole hydrochloride
  81. Green synthesis of La2O3–LaPO4 nanocomposites using Charybdis natator for DNA binding, cytotoxic, catalytic, and luminescence applications
  82. Eco-friendly drugs induce cellular changes in colistin-resistant bacteria
  83. Tangerine fruit peel extract mediated biogenic synthesized silver nanoparticles and their potential antimicrobial, antioxidant, and cytotoxic assessments
  84. Green synthesis on performance characteristics of a direct injection diesel engine using sandbox seed oil
  85. A highly sensitive β-AKBA-Ag-based fluorescent “turn off” chemosensor for rapid detection of abamectin in tomatoes
  86. Green synthesis and physical characterization of zinc oxide nanoparticles (ZnO NPs) derived from the methanol extract of Euphorbia dracunculoides Lam. (Euphorbiaceae) with enhanced biosafe applications
  87. Detection of morphine and data processing using surface plasmon resonance imaging sensor
  88. Effects of nanoparticles on the anaerobic digestion properties of sulfamethoxazole-containing chicken manure and analysis of bio-enzymes
  89. Bromic acid-thiourea synergistic leaching of sulfide gold ore
  90. Green chemistry approach to synthesize titanium dioxide nanoparticles using Fagonia Cretica extract, novel strategy for developing antimicrobial and antidiabetic therapies
  91. Green synthesis and effective utilization of biogenic Al2O3-nanocoupled fungal lipase in the resolution of active homochiral 2-octanol and its immobilization via aluminium oxide nanoparticles
  92. Eco-friendly RP-HPLC approach for simultaneously estimating the promising combination of pentoxifylline and simvastatin in therapeutic potential for breast cancer: Appraisal of greenness, whiteness, and Box–Behnken design
  93. Use of a humidity adsorbent derived from cockleshell waste in Thai fried fish crackers (Keropok)
  94. One-pot green synthesis, biological evaluation, and in silico study of pyrazole derivatives obtained from chalcones
  95. Bio-sorption of methylene blue and production of biofuel by brown alga Cystoseira sp. collected from Neom region, Kingdom of Saudi Arabia
  96. Synthesis of motexafin gadolinium: A promising radiosensitizer and imaging agent for cancer therapy
  97. The impact of varying sizes of silver nanoparticles on the induction of cellular damage in Klebsiella pneumoniae involving diverse mechanisms
  98. Microwave-assisted green synthesis, characterization, and in vitro antibacterial activity of NiO nanoparticles obtained from lemon peel extract
  99. Rhus microphylla-mediated biosynthesis of copper oxide nanoparticles for enhanced antibacterial and antibiofilm efficacy
  100. Harnessing trichalcogenide–molybdenum(vi) sulfide and molybdenum(vi) oxide within poly(1-amino-2-mercaptobenzene) frameworks as a photocathode for sustainable green hydrogen production from seawater without sacrificial agents
  101. Magnetically recyclable Fe3O4@SiO2 supported phosphonium ionic liquids for efficient and sustainable transformation of CO2 into oxazolidinones
  102. A comparative study of Fagonia arabica fabricated silver sulfide nanoparticles (Ag2S) and silver nanoparticles (AgNPs) with distinct antimicrobial, anticancer, and antioxidant properties
  103. Visible light photocatalytic degradation and biological activities of Aegle marmelos-mediated cerium oxide nanoparticles
  104. Physical intrinsic characteristics of spheroidal particles in coal gasification fine slag
  105. Exploring the effect of tea dust magnetic biochar on agricultural crops grown in polycyclic aromatic hydrocarbon contaminated soil
  106. Crosslinked chitosan-modified ultrafiltration membranes for efficient surface water treatment and enhanced anti-fouling performances
  107. Study on adsorption characteristics of biochars and their modified biochars for removal of organic dyes from aqueous solution
  108. Zein polymer nanocarrier for Ocimum basilicum var. purpurascens extract: Potential biomedical use
  109. Green synthesis, characterization, and in vitro and in vivo biological screening of iron oxide nanoparticles (Fe3O4) generated with hydroalcoholic extract of aerial parts of Euphorbia milii
  110. Novel microwave-based green approach for the synthesis of dual-loaded cyclodextrin nanosponges: Characterization, pharmacodynamics, and pharmacokinetics evaluation
  111. Bi2O3–BiOCl/poly-m-methyl aniline nanocomposite thin film for broad-spectrum light-sensing
  112. Green synthesis and characterization of CuO/ZnO nanocomposite using Musa acuminata leaf extract for cytotoxic studies on colorectal cancer cells (HCC2998)
  113. Review Articles
  114. Materials-based drug delivery approaches: Recent advances and future perspectives
  115. A review of thermal treatment for bamboo and its composites
  116. An overview of the role of nanoherbicides in tackling challenges of weed management in wheat: A novel approach
  117. An updated review on carbon nanomaterials: Types, synthesis, functionalization and applications, degradation and toxicity
  118. Special Issue: Emerging green nanomaterials for sustainable waste management and biomedical applications
  119. Green synthesis of silver nanoparticles using mature-pseudostem extracts of Alpinia nigra and their bioactivities
  120. Special Issue: New insights into nanopythotechnology: current trends and future prospects
  121. Green synthesis of FeO nanoparticles from coffee and its application for antibacterial, antifungal, and anti-oxidation activity
  122. Dye degradation activity of biogenically synthesized Cu/Fe/Ag trimetallic nanoparticles
  123. Special Issue: Composites and green composites
  124. Recent trends and advancements in the utilization of green composites and polymeric nanocarriers for enhancing food quality and sustainable processing
  125. Retraction
  126. Retraction of “Biosynthesis and characterization of silver nanoparticles from Cedrela toona leaf extracts: An exploration into their antibacterial, anticancer, and antioxidant potential”
  127. Retraction of “Photocatalytic degradation of organic dyes and biological potentials of biogenic zinc oxide nanoparticles synthesized using the polar extract of Cyperus scariosus R.Br. (Cyperaceae)”
  128. Retraction to “Green synthesis on performance characteristics of a direct injection diesel engine using sandbox seed oil”
https://doi.org/10.1515/gps-2023-0199
Keywords for this article
Au; ZnO nanocomposite; eco-friendly; photodegradation; rhodamine B dye
Creative Commons
BY 4.0

Articles in the same Issue

  1. Research Articles
  2. Green polymer electrolyte and activated charcoal-based supercapacitor for energy harvesting application: Electrochemical characteristics
  3. Research on the adsorption of Co2+ ions using halloysite clay and the ability to recover them by electrodeposition method
  4. Simultaneous estimation of ibuprofen, caffeine, and paracetamol in commercial products using a green reverse-phase HPTLC method
  5. Isolation, screening and optimization of alkaliphilic cellulolytic fungi for production of cellulase
  6. Functionalized gold nanoparticles coated with bacterial alginate and their antibacterial and anticancer activities
  7. Comparative analysis of bio-based amino acid surfactants obtained via Diels–Alder reaction of cyclic anhydrides
  8. Biosynthesis of silver nanoparticles on yellow phosphorus slag and its application in organic coatings
  9. Exploring antioxidant potential and phenolic compound extraction from Vitis vinifera L. using ultrasound-assisted extraction
  10. Manganese and copper-coated nickel oxide nanoparticles synthesized from Carica papaya leaf extract induce antimicrobial activity and breast cancer cell death by triggering mitochondrial caspases and p53
  11. Insight into heating method and Mozafari method as green processing techniques for the synthesis of micro- and nano-drug carriers
  12. Silicotungstic acid supported on Bi-based MOF-derived metal oxide for photodegradation of organic dyes
  13. Synthesis and characterization of capsaicin nanoparticles: An attempt to enhance its bioavailability and pharmacological actions
  14. Synthesis of Lawsonia inermis-encased silver–copper bimetallic nanoparticles with antioxidant, antibacterial, and cytotoxic activity
  15. Facile, polyherbal drug-mediated green synthesis of CuO nanoparticles and their potent biological applications
  16. Zinc oxide-manganese oxide/carboxymethyl cellulose-folic acid-sesamol hybrid nanomaterials: A molecularly targeted strategy for advanced triple-negative breast cancer therapy
  17. Exploring the antimicrobial potential of biogenically synthesized graphene oxide nanoparticles against targeted bacterial and fungal pathogens
  18. Biofabrication of silver nanoparticles using Uncaria tomentosa L.: Insight into characterization, antibacterial activities combined with antibiotics, and effect on Triticum aestivum germination
  19. Membrane distillation of synthetic urine for use in space structural habitat systems
  20. Investigation on mechanical properties of the green synthesis bamboo fiber/eggshell/coconut shell powder-based hybrid biocomposites under NaOH conditions
  21. Green synthesis of magnesium oxide nanoparticles using endophytic fungal strain to improve the growth, metabolic activities, yield traits, and phenolic compounds content of Nigella sativa L.
  22. Estimation of greenhouse gas emissions from rice and annual upland crops in Red River Delta of Vietnam using the denitrification–decomposition model
  23. Synthesis of humic acid with the obtaining of potassium humate based on coal waste from the Lenger deposit, Kazakhstan
  24. Ascorbic acid-mediated selenium nanoparticles as potential antihyperuricemic, antioxidant, anticoagulant, and thrombolytic agents
  25. Green synthesis of silver nanoparticles using Illicium verum extract: Optimization and characterization for biomedical applications
  26. Antibacterial and dynamical behaviour of silicon nanoparticles influenced sustainable waste flax fibre-reinforced epoxy composite for biomedical application
  27. Optimising coagulation/flocculation using response surface methodology and application of floc in biofertilisation
  28. Green synthesis and multifaceted characterization of iron oxide nanoparticles derived from Senna bicapsularis for enhanced in vitro and in vivo biological investigation
  29. Potent antibacterial nanocomposites from okra mucilage/chitosan/silver nanoparticles for multidrug-resistant Salmonella Typhimurium eradication
  30. Trachyspermum copticum aqueous seed extract-derived silver nanoparticles: Exploration of their structural characterization and comparative antibacterial performance against gram-positive and gram-negative bacteria
  31. Microwave-assisted ultrafine silver nanoparticle synthesis using Mitragyna speciosa for antimalarial applications
  32. Green synthesis and characterisation of spherical structure Ag/Fe2O3/TiO2 nanocomposite using acacia in the presence of neem and tulsi oils
  33. Green quantitative methods for linagliptin and empagliflozin in dosage forms
  34. Enhancement efficacy of omeprazole by conjugation with silver nanoparticles as a urease inhibitor
  35. Residual, sequential extraction, and ecological risk assessment of some metals in ash from municipal solid waste incineration, Vietnam
  36. Green synthesis of ZnO nanoparticles using the mangosteen (Garcinia mangostana L.) leaf extract: Comparative preliminary in vitro antibacterial study
  37. Simultaneous determination of lesinurad and febuxostat in commercial fixed-dose combinations using a greener normal-phase HPTLC method
  38. A greener RP-HPLC method for quaternary estimation of caffeine, paracetamol, levocetirizine, and phenylephrine acquiring AQbD with stability studies
  39. Optimization of biomass durian peel as a heterogeneous catalyst in biodiesel production using microwave irradiation
  40. Thermal treatment impact on the evolution of active phases in layered double hydroxide-based ZnCr photocatalysts: Photodegradation and antibacterial performance
  41. Preparation of silymarin-loaded zein polysaccharide core–shell nanostructures and evaluation of their biological potentials
  42. Preparation and characterization of composite-modified PA6 fiber for spectral heating and heat storage applications
  43. Preparation and electrocatalytic oxygen evolution of bimetallic phosphates (NiFe)2P/NF
  44. Rod-shaped Mo(vi) trichalcogenide–Mo(vi) oxide decorated on poly(1-H pyrrole) as a promising nanocomposite photoelectrode for green hydrogen generation from sewage water with high efficiency
  45. Green synthesis and studies on citrus medica leaf extract-mediated Au–ZnO nanocomposites: A sustainable approach for efficient photocatalytic degradation of rhodamine B dye in aqueous media
  46. Cellulosic materials for the removal of ciprofloxacin from aqueous environments
  47. The analytical assessment of metal contamination in industrial soils of Saudi Arabia using the inductively coupled plasma technology
  48. The effect of modified oily sludge on the slurry ability and combustion performance of coal water slurry
  49. Eggshell waste transformation to calcium chloride anhydride as food-grade additive and eggshell membranes as enzyme immobilization carrier
  50. Synthesis of EPAN and applications in the encapsulation of potassium humate
  51. Biosynthesis and characterization of silver nanoparticles from Cedrela toona leaf extracts: An exploration into their antibacterial, anticancer, and antioxidant potential
  52. Enhancing mechanical and rheological properties of HDPE films through annealing for eco-friendly agricultural applications
  53. Immobilisation of catalase purified from mushroom (Hydnum repandum) onto glutaraldehyde-activated chitosan and characterisation: Its application for the removal of hydrogen peroxide from artificial wastewater
  54. Sodium titanium oxide/zinc oxide (STO/ZnO) photocomposites for efficient dye degradation applications
  55. Effect of ex situ, eco-friendly ZnONPs incorporating green synthesised Moringa oleifera leaf extract in enhancing biochemical and molecular aspects of Vicia faba L. under salt stress
  56. Biosynthesis and characterization of selenium and silver nanoparticles using Trichoderma viride filtrate and their impact on Culex pipiens
  57. Photocatalytic degradation of organic dyes and biological potentials of biogenic zinc oxide nanoparticles synthesized using the polar extract of Cyperus scariosus R.Br. (Cyperaceae)
  58. Assessment of antiproliferative activity of green-synthesized nickel oxide nanoparticles against glioblastoma cells using Terminalia chebula
  59. Chlorine-free synthesis of phosphinic derivatives by change in the P-function
  60. Anticancer, antioxidant, and antimicrobial activities of nanoemulsions based on water-in-olive oil and loaded on biogenic silver nanoparticles
  61. Study and mechanism of formation of phosphorus production waste in Kazakhstan
  62. Synthesis and stabilization of anatase form of biomimetic TiO2 nanoparticles for enhancing anti-tumor potential
  63. Microwave-supported one-pot reaction for the synthesis of 5-alkyl/arylidene-2-(morpholin/thiomorpholin-4-yl)-1,3-thiazol-4(5H)-one derivatives over MgO solid base
  64. Screening the phytochemicals in Perilla leaves and phytosynthesis of bioactive silver nanoparticles for potential antioxidant and wound-healing application
  65. Graphene oxide/chitosan/manganese/folic acid-brucine functionalized nanocomposites show anticancer activity against liver cancer cells
  66. Nature of serpentinite interactions with low-concentration sulfuric acid solutions
  67. Multi-objective statistical optimisation utilising response surface methodology to predict engine performance using biofuels from waste plastic oil in CRDi engines
  68. Microwave-assisted extraction of acetosolv lignin from sugarcane bagasse and electrospinning of lignin/PEO nanofibres for carbon fibre production
  69. Biosynthesis, characterization, and investigation of cytotoxic activities of selenium nanoparticles utilizing Limosilactobacillus fermentum
  70. Highly photocatalytic materials based on the decoration of poly(O-chloroaniline) with molybdenum trichalcogenide oxide for green hydrogen generation from Red Sea water
  71. Highly efficient oil–water separation using superhydrophobic cellulose aerogels derived from corn straw
  72. Beta-cyclodextrin–Phyllanthus emblica emulsion for zinc oxide nanoparticles: Characteristics and photocatalysis
  73. Assessment of antimicrobial activity and methyl orange dye removal by Klebsiella pneumoniae-mediated silver nanoparticles
  74. Influential eradication of resistant Salmonella Typhimurium using bioactive nanocomposites from chitosan and radish seed-synthesized nanoselenium
  75. Antimicrobial activities and neuroprotective potential for Alzheimer’s disease of pure, Mn, Co, and Al-doped ZnO ultra-small nanoparticles
  76. Green synthesis of silver nanoparticles from Bauhinia variegata and their biological applications
  77. Synthesis and optimization of long-chain fatty acids via the oxidation of long-chain fatty alcohols
  78. Eminent Red Sea water hydrogen generation via a Pb(ii)-iodide/poly(1H-pyrrole) nanocomposite photocathode
  79. Green synthesis and effective genistein production by fungal β-glucosidase immobilized on Al2O3 nanocrystals synthesized in Cajanus cajan L. (Millsp.) leaf extracts
  80. Green stability-indicating RP-HPTLC technique for determining croconazole hydrochloride
  81. Green synthesis of La2O3–LaPO4 nanocomposites using Charybdis natator for DNA binding, cytotoxic, catalytic, and luminescence applications
  82. Eco-friendly drugs induce cellular changes in colistin-resistant bacteria
  83. Tangerine fruit peel extract mediated biogenic synthesized silver nanoparticles and their potential antimicrobial, antioxidant, and cytotoxic assessments
  84. Green synthesis on performance characteristics of a direct injection diesel engine using sandbox seed oil
  85. A highly sensitive β-AKBA-Ag-based fluorescent “turn off” chemosensor for rapid detection of abamectin in tomatoes
  86. Green synthesis and physical characterization of zinc oxide nanoparticles (ZnO NPs) derived from the methanol extract of Euphorbia dracunculoides Lam. (Euphorbiaceae) with enhanced biosafe applications
  87. Detection of morphine and data processing using surface plasmon resonance imaging sensor
  88. Effects of nanoparticles on the anaerobic digestion properties of sulfamethoxazole-containing chicken manure and analysis of bio-enzymes
  89. Bromic acid-thiourea synergistic leaching of sulfide gold ore
  90. Green chemistry approach to synthesize titanium dioxide nanoparticles using Fagonia Cretica extract, novel strategy for developing antimicrobial and antidiabetic therapies
  91. Green synthesis and effective utilization of biogenic Al2O3-nanocoupled fungal lipase in the resolution of active homochiral 2-octanol and its immobilization via aluminium oxide nanoparticles
  92. Eco-friendly RP-HPLC approach for simultaneously estimating the promising combination of pentoxifylline and simvastatin in therapeutic potential for breast cancer: Appraisal of greenness, whiteness, and Box–Behnken design
  93. Use of a humidity adsorbent derived from cockleshell waste in Thai fried fish crackers (Keropok)
  94. One-pot green synthesis, biological evaluation, and in silico study of pyrazole derivatives obtained from chalcones
  95. Bio-sorption of methylene blue and production of biofuel by brown alga Cystoseira sp. collected from Neom region, Kingdom of Saudi Arabia
  96. Synthesis of motexafin gadolinium: A promising radiosensitizer and imaging agent for cancer therapy
  97. The impact of varying sizes of silver nanoparticles on the induction of cellular damage in Klebsiella pneumoniae involving diverse mechanisms
  98. Microwave-assisted green synthesis, characterization, and in vitro antibacterial activity of NiO nanoparticles obtained from lemon peel extract
  99. Rhus microphylla-mediated biosynthesis of copper oxide nanoparticles for enhanced antibacterial and antibiofilm efficacy
  100. Harnessing trichalcogenide–molybdenum(vi) sulfide and molybdenum(vi) oxide within poly(1-amino-2-mercaptobenzene) frameworks as a photocathode for sustainable green hydrogen production from seawater without sacrificial agents
  101. Magnetically recyclable Fe3O4@SiO2 supported phosphonium ionic liquids for efficient and sustainable transformation of CO2 into oxazolidinones
  102. A comparative study of Fagonia arabica fabricated silver sulfide nanoparticles (Ag2S) and silver nanoparticles (AgNPs) with distinct antimicrobial, anticancer, and antioxidant properties
  103. Visible light photocatalytic degradation and biological activities of Aegle marmelos-mediated cerium oxide nanoparticles
  104. Physical intrinsic characteristics of spheroidal particles in coal gasification fine slag
  105. Exploring the effect of tea dust magnetic biochar on agricultural crops grown in polycyclic aromatic hydrocarbon contaminated soil
  106. Crosslinked chitosan-modified ultrafiltration membranes for efficient surface water treatment and enhanced anti-fouling performances
  107. Study on adsorption characteristics of biochars and their modified biochars for removal of organic dyes from aqueous solution
  108. Zein polymer nanocarrier for Ocimum basilicum var. purpurascens extract: Potential biomedical use
  109. Green synthesis, characterization, and in vitro and in vivo biological screening of iron oxide nanoparticles (Fe3O4) generated with hydroalcoholic extract of aerial parts of Euphorbia milii
  110. Novel microwave-based green approach for the synthesis of dual-loaded cyclodextrin nanosponges: Characterization, pharmacodynamics, and pharmacokinetics evaluation
  111. Bi2O3–BiOCl/poly-m-methyl aniline nanocomposite thin film for broad-spectrum light-sensing
  112. Green synthesis and characterization of CuO/ZnO nanocomposite using Musa acuminata leaf extract for cytotoxic studies on colorectal cancer cells (HCC2998)
  113. Review Articles
  114. Materials-based drug delivery approaches: Recent advances and future perspectives
  115. A review of thermal treatment for bamboo and its composites
  116. An overview of the role of nanoherbicides in tackling challenges of weed management in wheat: A novel approach
  117. An updated review on carbon nanomaterials: Types, synthesis, functionalization and applications, degradation and toxicity
  118. Special Issue: Emerging green nanomaterials for sustainable waste management and biomedical applications
  119. Green synthesis of silver nanoparticles using mature-pseudostem extracts of Alpinia nigra and their bioactivities
  120. Special Issue: New insights into nanopythotechnology: current trends and future prospects
  121. Green synthesis of FeO nanoparticles from coffee and its application for antibacterial, antifungal, and anti-oxidation activity
  122. Dye degradation activity of biogenically synthesized Cu/Fe/Ag trimetallic nanoparticles
  123. Special Issue: Composites and green composites
  124. Recent trends and advancements in the utilization of green composites and polymeric nanocarriers for enhancing food quality and sustainable processing
  125. Retraction
  126. Retraction of “Biosynthesis and characterization of silver nanoparticles from Cedrela toona leaf extracts: An exploration into their antibacterial, anticancer, and antioxidant potential”
  127. Retraction of “Photocatalytic degradation of organic dyes and biological potentials of biogenic zinc oxide nanoparticles synthesized using the polar extract of Cyperus scariosus R.Br. (Cyperaceae)”
  128. Retraction to “Green synthesis on performance characteristics of a direct injection diesel engine using sandbox seed oil”
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