Volume 239, Issue 2-3 - Special Issue: Solar Water Splitting And Artificial Photosynthesis (SWAP), Part 4; Guest Editors: Kevin Bethke, Jeyanthinath Mayandi and Smagul Karazhanov

In recent times, the convergence of metal oxide adorned graphene oxide (GO) composites has ignited substantial notice, driven by their potential to revolutionize electrochemical energy storage applications, particularly in the realm of supercapacitors. This surge in attention is attributable to the harmonious amalgamation of metal oxide nanoparticles with the versatile GO sheets, resulting in intricately nanostructured materials. The present investigation the synthesis of hybrid done by hydrothermal route, yielding nanostructured Co 3 O 4 /GO. Extensive electrochemical assessment reveals a pinnacle specific capacitance of 786.69 F/g at 1 mA/cm 2 current density within a 3 mol L −1 KOH aqueous medium, accompanied by commendable rate-handling capabilities.

Nickel doped zinc oxide (NZO) nanostructured thin films were prepared by hydrolysis and poly condensation reaction based on the sol–gel methodology. Nanostructured thin films were prepared over the glass substrate by dip coating. Prepared samples were annealed at 350 °C and 450 °C respectively to tune the desired characteristics. The XRD studies endorses the prepared films were polycrystalline in nature and high intensity sharp peaks were exhibited in (101) direction. EDAX results confirms the presence of Ni, Zn and O elements. FESEM results exhibits the spherical like morphology throughout the sample. The typical grain size of prepared samples are vary from 35 nm to 105 nm. Results of the FTIR divulges the different composition of prepared NZO samples. UV–vis spectrophotometer results reveals that the fabricated 1 at.% NZO thin films annealed at 450 °C were guaranteed to have the lowest absorbance of less than 10 %, while the 0.5 at.% NZO thin films have an energy band gap of roughly 3.08 eV. The obtained results of the prepared films are useful for devices like solar cells, optoelectronic devices, flat panel displays, anticorrosion and surface protection applicant against stainless steel etc.

Nanomaterials have a wide range of applications including novel biomedical studies are devoted to improving the functionality and effectively of traditional and unmodified systems, both drug carriers and common scaffolds for tissue engineering or advanced hydrogels for wound healing purposes. In this regard, metal oxide nanoparticles show great potential as versatile tools in biomedical science. In particular, iron oxide nanoparticles with different shape and sizes hold outstanding physiochemical characteristics, such as high specific area and structure that make them unique nanomaterials to be used in diverse aspects of medicine and biological systems. The challenges associated with the uncontrolled presence of antibiotics such as tetracycline in the environment have necessitated their removal through different techniques. Tetracycline is hard to degrade in living organisms and can even be converted to more toxic substances. In this article different type of iron oxides were subjected to photo degradation of antibacterial drug Tetracycline under UV light illumination and direct sunlight and the results were promising to degrade the drug within 20 min. The SEM, TEM, EDAX and XRD for the catalyst were characterized to confirm the presence of iron oxide, the size and shape of the particle. The kinetics of photo degradation of tetracycline followed the pseudo-first-order mechanism, proceeding through hydroxyl radicals generated under illumination. Moreover, the photo generated hydrogen peroxide could lead to heterogeneous photocatalytic processes on the surface of iron oxide nanoparticles; additionally generating hydroxyl and hydroperoxyl radicals enables photo degradation of tetracycline.

Extensive research has been focused on solid electrolytes exhibiting high lithium ion conductivity, with the goal of advancing their use in solid-state lithium-ion batteries. This study investigates the influence of a glass former, P 2 O 5 , on the structure and ionic conductivity of the solid electrolyte Li 2 SO 4 . Quenching of Li 2 SO 4 in the presence of P 2 O 5 resulted in a glass–crystal composite with significant amorphous content. The XRD analysis of the 20 mol% glass ceramics detects the presence of Li 4 P 2 O 7 without altering the original crystal structure. Notably, a conductivity value of 1.11 × 10 −4  S cm −1 at 563 K was observed for 20 mol%, which is around two orders higher than that of polycrystalline Li 2 SO 4 . The introduction of a small amount of glass former P 2 O 5 appears to loosen the structure of Li 2 SO 4 creating an easier path for Li + ion migration in the combined SO 4 –PO 4 network structure.

Transition metal phosphate based materials is being used for energy storage because of P–O covalent bond which facilitates more storage compared to other transition metals and this covalent bond enhanced the electrochemical performance for supercapacitor applications. Pure magnesium phosphate (Mg 3 (PO 4 ) 2 ) were synthesized via microwave synthesis as the composite varies with rGO (MgPO-XrGO) X =25,50,75,100mg . The prepared composite materials were examined employing XRD, Raman, FT-IR, SEM and XPS studies. Electrochemical studies (CV, EIS, GCD) of three electrode system for the prepared electrodes were performed using Biologic SP-150 with 2M (H 2 SO 4 ) as electrolyte. From the XRD results, triclinic structured MgPO was confirmed (JCPDS card #35–0329) and rGO has enhanced the crystallinity of MgPO composite. From Raman analyses, the well graphitization nature of rGO in composite MgPO was identified and from XPS analysis chemical composition of the elements was analyzed. The FT-IR fundamental modes of vibrations of PO 4 3 − ${\text{PO}}_{4}^{3-}$ ( γ 1 , γ 3 , γ 4 ) were obtained. The electrochemical analysis of the prepared material such as pure and composite materials showed better performance. The high specific capacitance was obtained for MgPO-50rGO because MgPO has high coordination with rGO. As Mg 2+ oxidation state has high chemical reactivity compared to other earth metals and other advantage is P–O covalent bond that enhanced the performance of the electrode. By facilitating these advantages, rGO is included as composite to develop the electrode to favor the practical applications. By using the optimum level rGO composite with MgPO 4 -50rGO a better new candidate was successfully developed for supercapacitor applications. The fabricated MgPO-50rGO//Activate carbon full cell set up exhibited the specific capacitance 61 Fg −1 at 1 Ag −1 , 21.7 Wh kg −1 energy density and 790.0 W kg −1 power densities and explored outstanding capacitive retention in 2 electrode full cell setup cyclic stability of 99.1 % over the 5000 cycles.

Teff ( Eragrostis tef ) is known as a staple grain crop which grown as edible seeds, remarkably in Ethiopia. However, after removal of its seeds, the hay obtained from this crop, are considered as agro-waste. Such a lignocellulosic agro-waste can be potentially exploited to prepare activated carbon to treat the harmful industrial effluents for detoxification. In this study, Teff hay (TH) was used as a precursor for preparing the activated carbon. The using H 2 SO 4 , chemical activation was carried out followed by carbonaceous process was undertaken to prepared activated carbon (AC) by pyrolysis. The prepared AC was modified as magnetized AC and characterized by various characterization methods. Further, as a bio-absorbent, its potency for adsorptive removal of Cu(II) ions was ascertained. Notably, the most studied and important process factors for adsorption, such as, initial concentration of metal ion, adsorbent dosage, pH, and contact time were subjected to optimization using response surface method (RSM). Further, to ensure the statistical optimization of aforementioned factors, the non-statistical techniques, genetic algorithm (GA) and artificial neural network (ANN) tools have been executed. In addition, the use of prepared Teff-hay based magnetized AC for the removal of Cu(II) by adsorption process was evaluated through different isotherms and kinetic approaches.

The use of light and a particular material known as a photocatalyst to degrade hazardous dyes in wastewater is an exciting new development in the field of photocatalytic dye degradation. In this study we investigated the characteristic properties and photocatalytic dye degradation of manganese doped lanthanum cobalt (LaCoO 3 (LCO)) nanoparticles (NPs). The NPs were synthesised using hydrothermal synthesis techniques and analysed its properties by utilising diverse technologies such as XRD, FeSEM with EDAX, Raman Spectroscopy, Photoluminescence spectroscopy and UV-DRS. From XRD analysis we found that the Mn doped LCO NPs have single phase rhombohedral crystal structures with R 3 ‾ $\overline{3}$ c space group and doping cause expansion of lattice. Surface morphology of the synthesised NPs was found to be altered from spherical to spine/rod like microstructure when Mn is incorporated to LCO lattice. PL spectroscopies show broad photoemission at 360–490 nm after absorbing 310 nm light. From the UV–Vis spectroscopy the optical bandgap of the materials around 4.5 eV, indicating they can absorb visible light effectively. LCO can absorb both UV and visible light, expanding its potential for outdoor applications under natural sunlight. Doping LCO with other elements can modify its bandgap and improve its activity towards specific dyes. LCO exhibits good chemical and thermal stability, making it reusable for multiple cycles. While LCO shows promise as a visible light photocatalyst for dye degradation, its efficiency can vary significantly depending on the specific conditions. We tested Congo Red (CR) dye with prepared photocatalyst to study how well they breakdown in visible light. Studies have reported degradation rates for different dyes ranging from 50 to 90 % within an hour under optimized conditions. The LCMO nanoparticles exhibited noteworthy photocatalytic activity, as evidenced by a degradation efficiency of 77 % within a 30 min timeframe. Our findings indicate that LCMO nanoparticles possess significant potential for environmental clean-up.

Considering the global energy crisis, alternative energy resources requirement is rising gradually. In light of dwindling energy resources, we turn to renewable alternatives. Storing this energy for future utilization remains a pressing endeavor. The ideal storage device should possess intensified energy density, power density, and cyclic stability. In this study, we have synthesized metal oxide with carbon based material nanocomposite such as BaO/NiO, BaO/NiO/rGO through cost effective co-precipitation method and their comparative performance for supercapacitor application were studied. Various characterizations were taken for the above synthesized material. X-ray diffraction (XRD) study confirmed the material formation and their crystallinity of the nanocomposite. BaO has tetragonal structure which was confirmed through JCPDS card number 26-0178 and NiO has rhombohedral structure which was confirmed through JCPDS card number 89-7390. To study electrochemical behaviour of electrode material and its cyclic stability, cyclic voltammetry (CV), galvanostatic charge–discharge (GCD) and electrochemical impedance spectroscopy (EIS) studies was executed. BaO/NiO/rGO possesses 1072 F/g specific capacitance at 0.3 A/g in aqueous 1 M KOH. The electrochemical action of hybrid device was setup and it revealed 224 F/g at 0.3 A/g within the charging potential of 1.6 V. Capacitive retention of 97.6 % was achieved by asymmetric hybrid supercapacitor even after 5000 cycles at 10 A/g, this shows prepared nanocomposite exceptional cyclic stability in energy storage application.

A mesoporous silica nanoparticle was synthesized by incorporating (3-glycidoxypropyl trimethoxysilane (GPTS)) via sol-gel co-condensation method using Pluronic P123 as structure directing agent and further reacted with ethanedithiol (ED) by post-surface modification process. To produce ethanedithiol-modified silica nanoparticles, approximately 20 wt% of GPTS was incorporated into the mesoporous silica pore walls by reacting tetraethyl orthosilicate and GPTS mixture (80:20 wt/wt%). Next, the ethanedithiol groups were introduced onto the silica surface by reacting with the epoxy part of GPTS and thiol groups of ED to produce the ED-modified-mesoporous silica adsorbent (MS-ED NPs) material. The synthesized MS-ED NPs show a high surface area, pore size, and mesopore volume of approximately 556 m 2 /g, 2.7 nm, and 0.052 cm 3 /g, respectively. The MS-ED NPs showed selective removal of mercury ions (Hg 2+ ) ions from the aqueous solution in the presence of other competitive metal ions with an adsorption amount of ∼168 mg/g with a removal capacity of approximately >90 % from the initial metal ion solutions (100 mg/L). The produced MS-ED NPs can be reusable up to 5 times by treating the metal-adsorbed MS-ED NPs in an acidic (0.1 M HCl) aqueous solution. Hence, the MS-ED NPs could be utilized to selectively remove Hg 2+ ions from aqueous wastewater.

Photocatalysis is considered a highly promising method to treat water samples contaminated with organic pollutants. Zirconium-doped lanthanum titanate (LaTi 1− x Zr x O 3 , where x  = 0 (LTO) and 0.05 (LZTO)) NPs were synthesized by the auto-combustion method and characterized by X-ray diffraction analysis (XRD), UV–visible diffuse reflectance spectroscopy (UV–vis DRS), Fourier transform infrared (FTIR), field emission scanning electron microscope (FE-SEM), and Raman spectroscopy. LTO and LZTO have tetragonal structure with an average crystalline size of 16 nm and 13 nm respectively. The band gap from UV–vis DRS was estimated to be 3.52 and 3.36 eV, respectively. The analysis of surface morphology indicates that the addition of Zr disrupted the crystal structure of LTO and transformed its spherical morphology into a rod-like structure. The Raman spectra of the LTO and LZTO crystal structure revealed the presence of A g and B 2g symmetry phonons. The magnetic properties were analysed by vibrating sample magnetometer (VSM) which confirmed the ferromagnetic behaviour. LZTO nanoparticles have been shown to have an efficiency of 92 % after 80 min of degradation. The synthesized LZTO samples exhibited enhanced ferromagnetic behaviour and improved photoactivity for the degradation of methylene blue dye as compared to those of pure LTO, make LZTO a good choice for magnetically separable photocatalysts that effectively purify contaminated water.

Researchers have shown considerable interest in the environmentally friendly synthesis of several nanoparticles particularly metal nano particles due to their multifaceted applications. The target of the current research includes the synthesis of nickel oxide nanoparticles (NiO-NPs) through the green route using the bark extract from Acacia Nilotica , and analyzed their chemical and surface morphological features using XRD, SEM, EDX, IR, UV–vis and photoluminescence spectroscopy. In addition, the corrosion inhibition ability and antimicrobial activity of the extract were also studied. The XRD analysis indicated that the NiO exist in the form of nanoparticles. It showed the formation of pure cubic NiO-NP with a prominent peak at 43.28° reflected from the plane (200). The crystallite size was found to be 15.83 nm. The SEM micrographs revealed that NiO-NPs appeared to be a bulk cluster-like structure on their surface.The EDX analysis displayed the presence of Ni and oxygen atoms. The photoluminescence spectrum demonstrated that the green synthesized metal oxide nanoparticles have a modified emission band due to the presence of oxygen deficiencies and induced surface imperfections. The Fourier transform infrared spectroscopy (FTIR) confirmed the association of peaks with the C–H and Ni–O bonds. The UV–vis study showed a maximum absorption at 264 nm. A study on the inhibition efficiency towards microbes confirmed that the prepared NiO-NPs have a good inhibition against selected microbes such as S. aureus , E. coli ,  Candida albicans , A. Niger . The mass loss system showed restraint 93.68 % effectiveness in the mild steel, and the electrochemical study supported the formation of a defensive protective layer on the cathodic locales of the carbon steel surface inhibiting corrosion.

Iron oxide nanoparticles have found wide applications in different fields of biomedicine and advanced catalytic applications. Several studies have suggested using iron oxide nanoparticle (Fe 2 O 3 -NPs) be a potential candidate for antibacterial activity assessment. Iron oxide nanoparticles, apart from being available extensively and cheap, also plays a vital part in multiple biological processes, making it an interesting choice of selection. The aim of the present study revolves around synthesis and characterization of iron oxide Fe 2 O 3 -NPs, followed by assessment of its antimicrobial activities and its catalytic behaviour. Synthesis of Fe 2 O 3 -NPs was performed by co-precipitation approach, and commercial iron oxide samples were studied for the comparison. The silver nanoparticles were also doped to the iron oxide nanoparticles and studied for the synergic effect. The samples characterization was done by UV-visible, X-ray diffraction (XRD), Scanning electron microscopy (SEM) with EDS and transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR), Raman Spectroscopy (RAMAN). Antimicrobial activity was checked by agar diffusion assay against Gram positive and Gram negative bacteria. The electrode performance of the iron oxide samples was done by cyclic voltammetry to explore their application in the energy storage and sensor.

The different pH-varied bismuth vanadate nanorods have been synthesized through a solvothermal method and utilized for XRD, HRTEM, SEM and electrochemical studies. The XRD spectra of BV-5 and BV-7 samples show the monoclinic structure. Both electrodes show rod-like morphology. Also, when the pH 7 the bismuth oxide shows large size nanorods compared with pH 5. The interspacing distance of the samples were reduced while the pH was increased. The electrochemical performance of the prepared BV-5 and BV-7 shows higher capacitance values of 235 and 167 F/g for BV-5 and BV-7 electrodes, also these electrodes show a maximum energy density value of 13.4 and 18.8 Wh/kg and related power density values are 720 and 867 W/kg, respectively. The power density value of the BV-7 electrode was increased without affecting the energy density value. Moreover, the cyclic retention of BV-7 shows 93 % at the 1000th cycle. Also, the capacitance and Rct values of BV-7 electrode are comparatively higher than pure BV-5 electrode.

Injera is a staple food in Ethiopian dine. This study aimed to investigate on leftover injera (LI) for producing biogas via anaerobic digestion (AD), while leftover injera is full of easily biodegradable components. Aiming to examine the impact of yeast addition on biogas production efficiency, it was found that the addition of 2 % volatile solids (VS) of stimulated yeast, daily biogas output increased by 520 and 550 ml after 12 and 37 days of anaerobic digestion, respectively, with rather steady biogas production. The rate at which gas production increased was drastically cut in half when yeast was left out of the control group. Biogas production increased by only 60 ml despite the addition of two portions of substrate and yeast. Biogas output in the yeast group after fermentation was also up 33.2 % compared to the control group. The yeast group’s anaerobic digesting system was more stable, as determined by the study of markers including volatile organic acids, alkalinity, and propionic acid. The findings can be used as a benchmark for future trials aiming to industrialise continuous anaerobic digestion, allowing for more flexible response to feed as waste LI as organic load.

In this manuscript, we present a facile and friendly sol-gel method to prepare bare and Zn-doped SnO 2 nanoparticles and measured the photocatalytic performance of the materials by measuring the degradation of MB dye under UV light irradiation. A variety of analytical techniques were employed to characterize the materials, including X-ray diffraction, UV–Vis spectroscopy, Photoluminescence (PL), Fourier Transform Infrared Spectroscopy (FT-IR) and Scanning Electron Microscopy (SEM). The X-ray diffraction (XRD) analysis reveals the presence of tetragonal SnO 2 nanostructures. The average crystallite size of the bare SnO 2 nanostructures was found to be 7.4 nm, but the addition of Zn dopant caused the size to increase to 10.5 nm. PL studies shows that the majority of emission energies fell within the SnO 2 NPs’ band gap, indicating defects related to oxygen vacancies or Sn interstitials. The morphological analysis of SEM exhibits the various forms of SnO 2  nanostructures which are densely agglomerate. The photocatalytic activity of the SZ 10 NPs was found to be MB (88 %). The results showed that the Zn doped SnO 2 exhibited good photocatalytic activity.

This work aims to investigate the morphological, mechanical and thermal characteristics of boron nitride (BN)-reinforced acrylonitrile-butadiene styrene (ABS) composites. ABS and ABS/BN composites with a maximum BN loading up to 8 wt% were developed using two-roll mill followed by compression molding. Scanning electron microscopy (SEM) images presented interlinking of BN flakes in the dimple texture of ABS. A modest decrease in tensile properties was observed for the composites. The tensile strength and impact strength for the ABS/BN8 specimen were lowered by 4.7 and 81.7 %, respectively. On the other hand, hardness increased by 3.39 % for ABS/BN8 composite. The interaction effect of BN in the ABS matrix on the thermal properties was assessed using thermo-gravimetric analysis (TGA). An enhancement in the thermal-stability was observed for BN incorporated ABS. There is a modest shift in glass transition ( T g ) temperature to a higher value for the ABS/BN composites.