Volume 235, Issue 12

Perovskite solar cells (PSC) comprising of organic–inorganic lead halide composition have been considered as the future candidates for substituting the costly crystalline silicon-based solar cells if the challenges of efficiency and stability are adequately addressed. PSCs have been known for the employment of costly materials serving as electron transport, hole transport layers and back contact electrode such as gold, silver, or aluminum, needing thermal deposition in high vacuum ambiance. Metallic electrodes have been observed as not robust and thus, prone to quick degradation hindering the overall photovoltaic functionality of PSC devices. Carbon-modified PSCs via utilization of carbon nanotubes (CNTs) have been a favorable choice in terms of longer stability and efficiency. Considering the overpowering potential of CNTs in transforming PSC device functionality, current review has been designed to elucidate the most recent progressions carried out in utilization of CNTs in PSCs. Furthermore, this review focussed a critical view on the utilization of CNTs-based PSCs for lower fill factors and other photovoltaic parameters in addition to the account of ways to solve these concerns. Photovoltaic community researchers need to develop cost effective methods for resolving the lower efficiencies and fill factors associated with use of CNTs and can further explore different novel materials to successfully modify CNTs for employment in PSCs.

A thermal process was employed to prepare a catalyst consisting of a mixture of metallic-Pt and rutile RuO 2 nanocrystals. This catalyst was used for the electrooxidation of 2-propanol in an alkaline solution. The effect of the catalyst composition on its microstructure, surface properties and catalytic activity was examined. With increasing the RuO 2 content, the catalytic activity increases, reaches its maximum and then decreases. The catalytic effect is a result of the bifunctional mechanism of the mixture of Pt and RuO 2 nanocrystals. The RuOH ad particles are formed on Ru atoms of the RuO 2 nanocrystals at potentials more negative than on Pt atoms. These oxy-species facilitate the dehydrogenation, breaking of C–C bonds and oxidation of both 2-propanol and its intermediates, adsorbed on assemblies of adjacent Pt atoms.

This study reports green synthesis and characterization of silver nanoparticles (Ag NPs) from Sophora mollis leaf extract. The use of S. mollis extract for preparation of Ag NPs was investigated using different techniques. Dark brown color indicates formation of nanoparticles. Fourier transform infra-red (FTIR) analysis revealed that plant extract act as a reducing and capping agent. Morphological aspects of Ag NPs were ascertained by means of SEM studies. Energy dispersive and FTIR spectroscopy results showed chemical composition and plant extract functionality respectively. X-ray diffraction (XRD) analysis showed particle size of 70 nm. Antibacterial activity of NPs was investigated by disc diffusion and minimum inhibitory concentration method. Antioxidant activity of NPs was shown by DPPH assay. The photo catalytic efficiency of synthesized Ag NPs was evaluated by degradation of methylene blue (MB) dye under UV irradiation. Ag NPs degraded MB dye up to 88% in 160 min. It is concluded that these NPs could be employed for degradation of toxic industrial effluents. Result proved the green synthesis of Ag NPs from S. mollis extract is clean, economical and safe method.

This study reports the fabrication of Fe 2 O 3 , Bi 2 O 3, and BiFeO 3 , characterization and evaluation of the photocatalytic performances for methylene blue dye degradation. The materials were synthesized by precipitation method and characterized by scanning electron microscopy, X-ray diffraction, energy dispersive X-rays analyses, and Fourier transform infrared analyses. The photocatalytic activities of Fe 2 O 3 , Bi 2 O 3 , and BiFeO 3 were compared by performing degradation experiments with 50 mL of 100 mg/L methylene blue solution. The as-prepared BiFeO 3 was found as 2.4 times and 1.7 times more effective than Fe 2 O 3 and Bi 2 O 3, with a 79, 47, and 57% catalytic activity, respectively. The degradation of methylene blue over the BiFeO 3 catalyst was optimized in terms of pH, catalyst dosage, temperature, and methylene blue concentration. The Eley–Rideal mechanism was proposed to describe the reaction kinetics in terms of the first order and second order kinetics model. Activation energy E (kJ/mol), enthalpy Δ H (kJ/mol), entropy Δ S (J/mol) and free energy Δ G (kJ/mol) were calculated as 20.8, 18.2, 197.5 and −45.3 respectively. The negative value of free energy shows that photodegradation is favored in present conditions.

The gamma ray induced degradation of moxifloxacin in aqueous media has been evaluated. The drug solutions (50 & 100 mg/L) were irradiated to absorbed doses of 0.3, 0.6, 0.9, 1.2, 1.5, 2, 3 and 4 kGy using Cs-137 gamma radiation source. The parameters such as drug initial concentration, oxidant (H 2 O 2 ) concentration and gamma ray absorbed doses were optimized. The efficiency of Advanced oxidation processes (AOP) was evaluated on the basis of degradation, reduction in chemical oxygen demand (COD) and toxicity reduction of the drug. The maximum degradation of 94.01 and 88.30% was achieved when drug solutions were exposed to gamma irradiation absorbed dose of 4 kGy which enhanced to 100 and 99.06% in the presence of H 2 O 2 (0.5 mL/L) for 50 and 100 mg/L respectively. A significant reduction in COD 72 and 75% for 50 mg/L while 65 and 69% in case of 100 mg/L was noted using gamma and gamma/H 2 O 2 respectively at absorbed dose of 4 kGy. The parameters such as dose constant (k), removal efficiency ( G -value), gamma ray absorbed doses required for 50, 90 and 99% degradation ( D 0.50 , D 0.90 and D 0.99 ) have been calculated. The radiolytic degradation was monitored by UV–Vis spectrophotometer and HPLC, FT-IR studies were performed to investigate the change in functional groups before and after treatment, while GC-MS analysis was carried out to monitor intermediates/degraded end-products. The FT-IR spectra has shown complete destruction of aromatic rings after radiation treatment but a minor peak appeared at 1216 cm −1 corresponding to CO stretching. The GC-MS study for the drug samples treated with gamma/H 2 O 2 has shown no any significant peak which confirms the complete degradation. The cytotoxicity of treated samples was carried out by hemolytic assay and mutagenicity using Ames test before and after each treatment. The hemolytic test showed 73.92% hemolysis, while gamma/H 2 O 2 treatment reduced the mutagenicity to 74.08 and 65.66% against TA98 and TA100 bacterial strains respectively. The response surface methodology (RSM) was employed to optimize the data. The obtained data elaborate that gamma/H 2 O 2 process is promising approach for the remediation of pharmaceutical waste effluent.

Graphene oxide (GO) synthesized via modified Hummers method was studied for adsorption of methylene blue (MB) and malachite green (MG) dyes from aqueous solutions. It is hypothesized that electrostatic interactions between dye molecules and surface of GO will facilitate charge carrier movements and degrade the dye in an efficient way. The as synthesized GO was characterized using various characterization techniques such as XRD, Raman, FTIR, UV–Vis, SEM and EDAX. The experimental results suggest that dye removal percentage will increase with increase in adsorbent dosage, time as well as solution pH and the process was exothermic in nature. The adsorption data at 293 K could be fitted by Langmuir equation with a maximum adsorption amount of 119.04, 102.4 mg/g and Langmuir adsorption equilibrium constant of 1.58, 0.867 L/mg for MB and MG dyes, respectively. The outcomes of present article will help not only to understand the adsorption characteristics of GO on MB and MG dyes but also paves path towards development of highly oxidized GO surface for degradation of complex dyes.

The controlling of alkaline scale deposition on carbon steel surface in seawater by Oat extract was probed by means of current/time transients, electrochemical impedance spectroscopy (EIS) tests and scanning electron microscopy (SEM), high-performance liquid chromatography (HPLC), Fourier-transform infrared (FT-IR), X-ray diffraction (XRD) examinations. Nucleation, scale formation and coverage of carbon steel with alkaline scales were detected by current/time curves. The results demonstrate that the retardation in alkaline scale formation is controlled by Oat extract, with 86% efficiency at the highest concentration. The scale growth inhibition is due to the adsorption of Oat extract components on the active growth sites of crystal surfaces.

This study focusses on the production of biodiesel by reacting the heterogeneous based nano-catalysts with used cooking oil in the presence of methanol. The CZO nanoparticles (NPs) were synthesized by co-precipitation method and characterized by different techniques. Biodiesel was characterized by the gas chromatograph (GC) and Fourier Transform Infra-red Spectroscopy (FTIR). Optimum conditions for the maximum biodiesel yield (90%) were 0.2% (w/w) catalyst dose, 3:1 methanol to oil ratio, 50 °C reaction temperature, 150 min reaction time and 136 rpm stirring speed. The kinetic modeling and the thermodynamic factors like enthalpy (Δ H ), activation energy ( Ea ), entropy (Δ S ) and free energy (Δ G ) were operated on all the data. Mean and standard deviation was used for analysis of data. The results indicate the maximum biodiesel yield under the optimum reaction conditions, which is promising to reduce the pollution such as air pollution and greenhouse effect for sustainable environmetal development.

Fabric dyed with disperse dyes followed a reduction clearing process (RCP)/chemical clearing process (CCP) to remove the unfixed dye from the fabric. In the clearing process, unfixed dyes and chemicals are discharged into streams. To combat this issue, an environment friendly approaches is explored that is a biological clearing using indigenous fungal strains of white-rot fungi ( Pleurotus ostreatus and Ganoderma lucidum ). In this context, fabrics dyed with three disperse dyes (Foron Blue E-BL 150, Foron Rubine RD-GFL and Foron Brilliant Yellow S-6GL) were considered. The fabric cleared with biological clearing process improved the quality of fabric versus chemically cleared fabric and among the tested strains, G. lucidum showed higher efficiency for color strength improvement. However, no significant difference in tensile and tear strength of all fabric samples was observed. The quality of effluents in clearing reduction process for three dyes was assessed and it was observed that water quality parameters including chemical oxygen demand (COD), total organic carbon (TOC), biological oxygen demand (BOD), total suspended solids (TSS), pH, dissolved oxygen (DO) and total dissolved solids (TDS) improved significantly and results revealed that the biological clearing approach can substitute chemical reduction clearing process for fabric dyed with dyes, which is greener and eco-friendly versus conventional processes to avoid unfixed dyes discharge in to water bodies.

The purpose of present work is to fabricate rhodium nanoparticles in Poly(N-isopropylmethacrylamide-acrylic acid) [p(NMAA)] microgel system. Synthesized polymer [p(NMAA)] microgels and rhodium nanoparticles loaded [Rh-p(NMAA)] microgels were analyzed by FTIR (Fourier Transform Infra-red) spectroscopy, XRD (X-ray Diffraction) analysis and UV/Vis (Ultraviolet–Visible) spectroscopy. Catalytic reductive conversion of P -nitrophenol ( P -Nph) into P -aminophenol ( P -Aph) via Rh-p(NMAA) was used to evaluate the catalytic activity of the hybrid microgel [Rh-p(NMAA)]. Kinetic study of catalytic reductive conversion of P -Nph was explored by considering various reaction parameters. It was found that the value of first order observed rate constant ( k obs ) was varied from 0.019 to 0.206 min −1 with change in concentration of sodium borohydride (SBH) from 3 to 14 mM at given temperature. However, further increment in concentration of SBH from 14 to 17 mM, reduced the value of k obs from 0.206 to 0.156 min −1 . The similar dependence of k obs on concentration of P -Nph was observed at specific concentration of SBH and Rh-p(NMAA) at constant temperature. Kinetic study reveals that conversion of P -Nph to P -Aph takes place on the surface of rhodium nanoparticles (RhNPs) by adopting different reactions intermediates and obeys the Langmuir-Hinshelwood mechanism. Reduction efficiency of recycled Rh-p(NMAA) catalytic system was also measured and no significant reduction in the percentage catalytic activity was obtained up to four cycles for P -Nph conversion into P-Aph.

Biochar caged zirconium ferrite (BC-ZrFe 2 O 5 ) nanocomposites were fabricated and their adsorption capacity for Reactive Blue 19 (RB19) dye was evaluated in a fixed-bed column and batch sorption mode. The adsorption of dye onto BC-ZrFe 2 O 5 NCs followed pseudo-second-order kinetics ( R 2  = 0.998) and among isotherms, the experimental data was best fitted to Sips model as compared to Freundlich and Langmuir isotherms models. The influence of flow-rate (3–5 mL min −1 ), inlet RB19 dye concentration (20–100 mg L −1 ) and quantity of BC-ZrFe 2 O 5 NCs (0.5–1.5 g) on fixed-bed sorption was elucidated by Box-Behnken experimental design. The saturation times ( C t / C o  = 0.95) and breakthrough ( C t / C o  = 0.05) were higher at lower flow-rates and higher dose of BC-ZrFe 2 O 5 NCs. The saturation times decreased, but breakthrough was increased with the initial RB19 dye concentration. The treated volume was higher at low sorbent dose and influent concentration. Fractional bed utilization (FBU) increased with RB19 dye concentration and flow rates at low dose of BC-ZrFe 2 O 5 NCs. Yan model was fitted best to breakthrough curves data as compared to Bohart-Adams and Thomas models. Results revealed that BC-ZrFe 2 O 5 nanocomposite has promising adsorption efficiency and could be used for the adsorption of dyes from textile effluents.

Mixed surfactant systems are used in different applied fields like pharmaceutical formulation rather than single surfactant. Therefore, the determination of the clouding nature of the triton X-100 (TX-100) + Tween 80 (TW-80) mixture was carried out in H 2 O and polyvinyl alcohol (PVA). In the occurrence of PVA, the cloud point (CP) values of TX-100 initially enhance with enhancing the concentration of PVA and tend to decrease after a certain concentration. For different ratios of TX-100 and TW-80 mixture having the same concentration of both solutions, CP values increase through the decreasing ratios of TX-100 with/without PVA. In the presence of polymer, at higher ratios of TX-100 than TW-80, the CP values are higher in magnitudes in comparison to the aqueous medium but at lower ratios of TX-100, the value of CP are lower in magnitudes in comparison to the aqueous system. The CP values of the TX-100 + TW-80 mixture in the salt system are lower in magnitudes than the aqueous medium in both the absence/presence of PVA. However, a reduction of CP values was obtained to a large extent for Na 2 SO 4 over NaCl in the case of lower volume ratios of TX-100. Various thermodynamic variables (standard free energy ( Δ G c o ${\Delta}{G}_{c}^{o}$ ), standard enthalpy ( Δ H c o ${\Delta}{H}_{c}^{o}$ ), standard entropy ( Δ S c o ${\Delta}{S}_{c}^{o}$ ) change, thermodynamic parameters of transfer (free energy of transfer ( Δ G c , t o ${\Delta}{G}_{c,t}^{o}$ ), and transfer of enthalpies ( Δ H c , t o ${\Delta}{H}_{c,t}^{o}$ )) of phase transition) were also determined.

Critical micelle concentration (CMC) is one of the important nominal characteristics of the surfactants which can be measured using various methods. In this study, to detect the CMC of two ionic surfactants, cetyltrimethylammonium bromide (CTAB) and sodium dodecyl sulfate (SDS), two methods were utilized: (a) optical fiber and (b) drop profile analysis tensiometry (PAT) techniques. The spectrum width center and surface tension of the solutions at different concentrations of the surfactant were measured. The preliminary outcomes showed a compliance between optical fiber method and PAT technique. However, there were differences in the behavior of two surfactants in optical fiber measurement. In this method, when the solid surface of fiber is put in the system, the interactions between surfactant molecules and the fiber surface must be carefully considered.

Cyclic voltammetry, 1 H nuclear magnetic resonance and quantum chemistry calculations were applied to explore the hydrogen bond interactions between ascorbic acid (AA) and glycine. The experimental results demonstrate the existence of hydrogen bonds in AA-glycine system, which has a significant effect on the oxidation peak potentials and currents of AA and the chemical shifts of glycine. The formation of hydrogen bonds between AA and glycine were further confirmed by the density functional theory, quantum theory of atoms in molecules and natural bond orbital analyses.

Three types (type-A, B, and C) of composite polymeric membranes (CPMs) based on poly vinyl chloride (PVC) and different fillers (sodium polyacrylate and sodium polyacrylate-graphite) soaked in water and 0.5 N HCl were prepared using solvent casting method. Different physicochemical parameters such as microscopic surface study, water uptake, perpendicular swelling, density, porosity (ε), ion exchange capacity, and conductivity of the as the prepared CPMs were evaluated. Interestingly, type-A CPM cast with filler-A has greater values of the above parameters except density and ionic conductivity than those of type-B and C CPMs. The water uptake of type-A, B and C composite membranes was respectively in the range of 220.42–534.70, 59.64–41.65, and 15.94–2.62%. Ion exchange capacity of type-A, B and C CPMs was in the range of 3.669 × 10 7 –2.156 × 10 7 , 5.948 × 10 7 –1.258 × 10 7 , and 1.454 × 10 7 –1.201 × 10 7  m.eq.g −1 respectively while the conductivity order was type-A < B < C. These types of CPMs may be helpful in many applications including proton exchange membranes, fuel cell like devices, as sensors for different metals, gas purification, water treatment, and battery separators.

Cobalt doped nickel ferrites were fabricated by sol gel route and the dielectric constant, tangent loss and AC conductivity were investigated as a function of Co doping. The X-ray diffractometer characterization confirmed that the Co x Ni 1− x Fe 2 O 4 with doping concentration ( x  = 0.1, 0.2, 0.3, 0.4, and 0.5) have cubic spinel structure. In the XRD spectrum there appear extra peaks of Fe 2 O 3 as an impurity that is gradually disappear by increasing doping ratio of cobalt ions, which is an indication of high crystallinity. The structural parameters (lattice constant, grain size, dislocation density, X-rays density and packing factor) are greatly influenced by the doping of cobalt atoms i.e., lattice constant increases. The crystal size increases from 30 to 42.26 nm by cobalt substitution in the pure nickel ferrites. The Fourier Transform IR Spectroscopy indicate shift in peaks to lower frequency region because cobalt doping reduced binding energy between metal ion and oxygen ions. Atomic structure of cobalt doped nickel ferrites examined by the Raman spectroscopy. Co x Ni 1− x Fe 2 O 4 shows Raman mode at ∼285, ∼477, ∼563, ∼624 and ∼704 cm −1 . There is unnoticeable Raman shift due to the doping of cobalt’s atoms.

We examined systematically how self-assembled monolayers (SAMs) of different mercaptoacids affect the spectral shift of the localized surface plasmon resonance in silver nanoplates and nanospheres. We observed a clear trend in the magnitude of a redshift with a molecular length or the SAM thickness within a homologous series of aliphatic mercaptoacids: the thicker shell the stronger the red shift. Using classic Mie theory for plasmonic core-dielectric shell spheres and oblate spheroids we developed the method for determination of a pseudo-refractive index in SAM of different molecules and obtained a good correlation with the reference refractive indices for bulk long-chain aliphatic acids, but only in case of silver nanoplates. Calculations for silver core–shell nanospheres gave overestimated values of refractive index perhaps due to restrictions of Mie theory on the minimum particle size.