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Silica doped iron oxide (SiO2 doped Fe2O3) nanoparticles (NPs) were successfully synthesized by co-precipitation method at 70 °C using different solvents (acetonitrile, n-hexane and isoamyl alcohol). The synthesized NPs were characterized by FT-IR, X-Ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), thermal gravimetric analysis-differential scanning calorimetry (TGA-DSC) and dynamic light scattering (DLS) techniques. The size of SiO2 doped Fe2O3 NPs was in the range of 5.89 nm–19.89 nm and ellipsoidal morphology with tendency of aggregate formation due to dipole-dipole interactions. The solvents showed variable effect on physico-chemical properties of the NPs. As-synthesized NPs were also evaluated for the antimicrobial activity against set of bacterial and fungal strains i.e., Candida parapsilosis, Aspergilus niger, Bacillus subtilis and Escherichia coli. It was observed that solvents also affected the NPs antimicrobial activity. The SiO2 doped Fe2O3 NPs prepared in acetonitrile showed highest antibacterial as well as antifungal activity. The MIC values were recorded to be 0.31 mg/L and 0.21 mg/L (acetonitrile) and 0.24 mg/L and 0.18 mg/L (isoamyl alcohol) for C. parapsilosis and A. niger, respectively. NPs prepared in n-hexane showed the MIC value of 0.09 mg/L. The photocaalytic activity (PCA) was evaluated by degrading Rhodamine B (RhB) dye. The RhB degradation was 83% for Fe2O3 NPs, which was enhanced considerably in case of doping, solvents also showed variable effect on the PCA for RhB dye degradation. Results revealed that the SiO2 doped Fe2O3 NPs are efficient antimicrobial agent as well as highly active photocatalysts and could possibly be used for the degradation of dyes in textile wastewater.

Heterogeneous semiconductor photocatalyst (Ti0.85Sn0.15O2) was synthesized by addition of TiO2 solution into Sn(OH)4 solution via sol–gel method using docusate sodium salt surfactant as model controlling agent while annealing at 800 °C. The structural, morphological and crystalline features of the synthesized sample were explored by using different microscopic and spectrophotometric techniques. The quantitative phase analysis and Rietveld refinement of XRD spectra was done to confirm the formation of Ti0.85 Sn0.15O2 nanocomposite. Optical electronegativity and refractive index was determined by using band gap energy. Their photocatalytic activity was estimated by using chlorpyrifos (CP) a class of organophosphorus pesticides, as a model of organic pollutants under solar light irradiations.

Surfactant controlled synthesis of La/SnO2–TiO2 nanocomposite was studied by using anionic surfactant dioctyl sulfosuccinate sodium salt (DOSS) synthesized via sol–gel method followed by hydrothermal method by using different lanthanum precursors. The structural investigation, thermal degradation, kinetics, thermodynamics properties, crystallite size, morphology, surface and photocatalytic properties of synthesized samples were studied by using different characterization techniques i.e. Thermogravimetric analysis (TGA), Fourier transform-infrared spectroscopy (FTIR), Particle Size Analyzer (PSA), Powder X-ray diffraction (XRD), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), and Ultraviolet–Visible spectrophotometer (UV–VIS). Band gap calculations and optical properties of both SnO2–TiO2 and La/SnO2–TiO2 were studied by using UV–Visible spectroscopy. The performance of both SnO2–TiO2 and La/SnO2–TiO2 nanocomposites as a photocatalytic agent was also investigated for the degradation of methylene blue (MB) under the illumination of sunlight.

Lanthanum (La) supported on tin oxide-titanium oxide (SnO2-TiO2 ) nanoparticles were prepared by a sol–gel method followed by a hydrothermal method. Effect of different solvents (ethyl acetate, benzyl alcohol, ethylene glycol) on the particle size and catalytic activity was investigated. The nanomaterial was characterized by transmission electron microscopy, powder X-ray diffraction, scanning electron microscopy, fourier transform infrared spectroscopy, and energy dispersive X-ray. The catalytic and optical properties were studied using solid-phase spectrophotometry and ultraviolet–visible spectroscopy, respectively. Gas chromatography-mass spectrometry (GC-MS) was used to detect the intermediates during the catalytic degradation of methylene blue. It was observed that with decrease in the dielectric constant (e) of the solvent, the bandgap and particle size decrease and catalytic efficiency increases. Hence, the highest catalytic activity was observed with the solvent having the least dielectric constant.

Endosulfan is the organochlorine pesticide and highly toxic to human and animal. Although its solubility is less in water but is persistent in soil. In this study, CeO2–ZnO nanocomposites have been prepared with hydrothermal method by using N-dodecyl-N,N-dimethyl-3-ammonio-1-propanesulfonate (SB3-12) zwitterionic surfactant. Cadmium sulphide was doped on CeO2–ZnO nanocomposites to enhance its catalytic efficiency. The structural characterization was carried out by using different techniques like FTIR, XRD, DLS, SEM and UV–Vis spectroscopy. Lattice contraction and decrease in oxygen vacancies was observed with increase in dopant concentration, which can be attributed to the Cd2+ substitution on CeO2–ZnO nanocomposites. These alterations in nanocomposites ensues the increase in particle size along with the blue shift in band gap energy. The catalytic efficiency of nanocomposites against endosulfan increases when the oxygen vacancy concentration is higher (with decrease in dopant concentration).

Surfactant-assisted synthesis of leucite (KAlSi2O6) nanoparticles was carried out by a hydrothermal method using an anionic surfactant at variable temperatures and surfactant concentrations. The newly synthesized leucite nanoparticles were characterized by FTIR, TGA, XRD, FESEM, and TEM. These nanoparticles have a wide and direct band gap at their smallest particle size (E g = 3.30 eV), showing a significant quantum confinement effect. Samples of leucite were prepared at 180°C with different SDS concentrations 0.006, 0.007, 0.008, 0.009, and 0.01 M and were used to degrade methylene blue under ultraviolet radiations. These samples degraded methylene blue to 18.5, 31.7, 45.81, 31.61, 30.1%, respectively. The most effective catalyst is the one which was synthesized at 200°C and the CMC value of the surfactant (sodium dodecyl sulfate) having the percentage degradation of 49.1%.

In the present work, tin oxide–titanium oxide (SnO2TiO2) nanoparticles were synthesized via sol–gel method and doping of lanthanum (La) on tin oxide–titanium oxide (La/SnO2TiO2) nanoparticles was carried out using hydrothermal and reflux methods. Effect of different preparation methods on the size and catalytic properties of nanoparticles was investigated. The La/SnO2TiO2 nanoparticles were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, powder X-ray diffraction and solid phase spectroscopy. The UV–Vis spectroscopy was used to investigate its catalytic properties for methylene blue degradation. It was found that La/SnO2–TiO2 nanoparticles prepared by hydrothermal method have small size and maximum degradation capacity. The red shift in La nanoparticles was observed with band gap of 4.25 eV as compared to bulk material.

Gd/SnO2–TiO2 nanoparticles were synthesized by using ultrasonic and hydrothermal methods. Effect of concentration of gadolinium (Gd) precursor on particle size and activity of nanoparticles was studied. It was observed that the particle size increases with the increase in concentration of gadolinium precursor. Gd/SnO2–TiO2 nanoparticles were characterized by TEM, SEM, EDX, TGA, FTIR and powder XRD. Band gap calculation was done by using Solid Phase Spectrophotometer to determine the optical properties of nanoparticles. The effect of concentration of Gd on band gap was investigated and red shift was observed for Gd/SnO2–TiO2 from 5.3 to 2.0 eV. Photocatalytic degradation of Methylene Blue was carried out to determine the catalytic properties of Gd/SnO2–TiO2. It was found that Gd/SnO2–TiO2 nanoparticles prepared with 0.004 M concentration of Gd precursor degraded the dye more effectively as compared to the samples prepared with 0.005 and 0.006 M concentrations of Gd.

Zinc sulfide (ZnS) thin films were prepared on indium tin oxide-coated glass by electrodeposition using aqueous zinc sulfate, thiourea, and ammonia solutions at 80°C. The effects of sulfurization at temperatures of 350°C, 400°C, 450°C, and 500°C on the morphological, structural, optical, and electrical properties of the ZnS thin films were investigated. X-ray diffraction analysis showed that the ZnS thin films exhibited cubic zincblende structure with preferred (111) orientation. The film crystallization improved with increasing annealing temperature. Field-emission scanning electron microscopy images showed that the film morphology became more compact and uniform with increasing annealing temperature. The percentage of sulfur in the ZnS thin films increased after sulfurization until a stoichiometric S/Zn ratio was achieved at 500°C. The annealed films showed good adhesion to the glass substrates, with moderate transmittance (85%) in the visible region. Based on absorption measurements, the direct bandgap increased from 3.71 eV to 3.79 eV with annealing temperature, which is attributed to the change of the buffer material composition and suitable crystal surface properties for effective p–n junction formation. The ZnS thin films were used as a buffer layer in thin-film solar cells with the structure of soda-lime glass/Mo/Cu2ZnSnS4/ZnS/ZnO/Al grid. The best solar cell efficiency was 1.86%.

Copper zinc tin sulfide (Cu 2 ZnSnS 4 ; CZTS) precursors were electrochemically deposited on Mo-coated glass substrates from aqueous solutions following by annealing. The effect of three complexing agents, trisodium citrate, ethylenediamine tetraacetic acid and tartaric acid, on the structural, morphological and compositional properties of CZTS thin films was investigated. The annealed thin films were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy, and energy-dispersive X-ray spectroscopy (EDS), UV–vis absorption and Raman scattering spectroscopies. XRD patterns of the synthesized films revealed the preferred orientation of the (1 1 2), (2 2 0), (2 0 0) and (3 1 2) planes, confirming the kesterite structure of CZTS. The film prepared without a complexing agent was uneven with some pores and cracks, whereas those prepared using complexing agents exhibited good coverage with some overgrown particles on the surface of the films. EDS analysis revealed that the films deposited using trisodium citrate were nearly stoichiometric for CZTS. Voltammetric studies suggested that trisodium citrate is a suitable complexing agent because it helps to align the deposition potentials of Cu, Zn, and Sn. UV–vis absorption spectra confirmed the films possessed a direct bandgap between 1.33 and 1.47 eV, which is quite close to the optimum value for a semiconductor material as an absorber in solar cells. We fabricated solar cells with the structure soda-lime glass/Mo/CZTS/CdS/i-ZnO/ZnO:Al/Al with a maximum conversion efficiency of ∼2.9%.

Surfactant controlled synthesis of magnesium oxide-tin oxide (MgO-SnO2) nanocatalysts was carried out via the hydrothermal method. Concentration of sodium dodecyl sulfate (SDS) was varied while all other reaction conditions were kept constant same for this purpose. Furthermore, MgO-SnO2 nanocatalysts were also prepared by changing the precursor’s concentration. These precursors are magnesium nitrate Mg(NO3)2 · 6H2O and tin chloride (SnCl4 · 5H2O). The influence of these reaction parameters on the sizes and morphology of the nanocatalysts were studied by using Fourier transform infrared (FTIR) spectroscopy, Scanning electron microscopy-Energy dispersive X-ray (SEM-EDX), Powder X-ray diffraction (XRD), Transmission electron microscopy and Thermo gravimetric analysis (TGA). The catalytic efficiency of MgO-SnO2 was checked against 2,4-dinitrophenylhydrazine (DNPH), which is an explosive compound. The nanocatalysts were found as a good catalyst to degrade the DNPH. Catalytic activity of nanocatalysts was observed up to 19.13% for the degradation DNPH by using UV-spectrophotometer.

Conventional heating method and hydrothermal method were used for the synthesis of CaO nanoparticles and CaO/MgO nanocomposites under solvent control conditions. Ca(NO3)2 and Mg(NO3)2 were used as precursors, amyl alcohol as surface directing agent and NaOH as source of OH−. Different samples of CaO were prepared by conventional heating method in order to investigate the effect of calcination temperature and stirring time. Similarly two different kinds of sets of CaO as well as of CaO/MgO were synthesized under hydrothermal conditions for the investigation of effect of solvent and temperature on catalytic efficiency. Characterizations of these samples were carried out by Powder X-ray Diffractions (XRD), Thermo Gravimetric Analysis (TGA), Field Emission Scanning Electron Microscope (FESEM) Energy dispersive X-ray (EDX) and Fourier Transformed Infrared spectroscopy (FTIR). The synthesized samples of CaO and CaO/MgO were used to degrade methylene blue under UV-Visible conditions, which is an organic pollutant of waste from industries and causing serious health problems. First order data for degradation for methylene blue at λmax = 665 nm was used to quantify the degradation. Effect of solvent was found to be prominent in all samples. Similarly effect of temperature variation was also pronounced on catalytic efficiency as indicated by value of k.

In vitro study to evaluate toxic effects of metal oxides nanoparticles on energy producing cycle was conducted. In this study oxidation of sodium succinate in aqueous solution was investigated by using potassium ferricyanide as an oxidizing agent. Kinetic measurements were carried out on kinetic mode of spectrophotometer at λmax 420 nm. Effect of different metal oxides (MgO and CaO) nanoparticles was observed on the oxidation of succinate at 25 ± 0.5 °C. These metal oxides nanoparticles were prepared by hydrothermal method and their characterization were done by using FTIR, TGA, SEM-EDX, TEM and XRD. Kinetic results indicated that these nanoparticles inhibit the conversion of succinate into fumerate. The inhibition is directly dependent on particle size of the nanoparticles and it was observed that particle size is inversely related to the oxidation rate of succinate. It was concluded at the end that elevated concentrations of metal oxides nanoparticles can severely affect the Krebs cycle by inhibiting succinate oxidation and lead to various metabolic disorders.

Copper zinc tin sulfide (CZTS, Cu2ZnSnS4) is a low band gap semiconductor that is attractive for use in solar cells. We investigated the dependence of the structure and properties of CZTS thin films on the temperature used to sulfurize precursor thin films composed of copper, zinc and tin fabricated by electrochemical deposition. The precursor films were sulfurized in a furnace with three zones, which allowed fine control of the sulfurization temperature between 250 and 400 °C. X-ray diffraction and Raman spectroscopic measurements confirmed that the films were composed of CZTS following sulfurization. The grain size and crystallinity of the films increased with sulfurization temperature. The composition of CZTS also varied with sulfurization temperature. The proportions of Cu and Zn increased while that of Sn decreased with increasing sulfurization temperature. Absorption and reflectance spectra revealed that the absorption coefficients and band gaps of the CZTS films varied with sulfurization temperature between 3–4.1 × 104 cm−1 and 1.4–1.53 eV, respectively. Solar cells containing CZTS sulfurized at 400 °C showed a maximum efficiency of 2.04 %, which was attributed to the higher crystallinity and larger grain size of CTZS compared with thin films sulfurized at lower temperatures. Our results show that control of sulfurization temperature is an important factor in optimizing the performance of CZTS thin films in solar cells.

Synthesis of Magnesium oxide (MgO) nanoparticles and zinc deposited magnesium oxide (Zn/MgO) nanoparticles was carried out using hydrothermal and deposition-precipitation method with the variation of 1-Propanol (organic solvent) concentration, sodium hydroxide and urea concentration. The nanoparticles were characterized by using FTIR, TGA, SEM-EDX, TEM and XRD. The photocatalytic efficiency of MgO and Zn/MgO nanoparticles was studied by degradation of 2,4,6-trinitrophenol (TNP), which is highly acute and toxic and causes skin and eyes diseases, liver malfunction and tumor formation. Photodegradation of TNP was carried out under UV irradiation and confirmed by using HPLC and GC-MS. MgO and Zn/MgO nanoparticles that were synthesized by using urea showed higher first-order rate constant (k) value and percentage degradation as compared to nanoparticles that were synthesized using NaOH. It was observed that the concentration of solvent has direct relation with the k value of degradation of TNP.

The kinetics of vitamin C by ferric chloride hexahydrate has been investigated in the aqueous eth� anol solution of basic surfactant viz. octadecylamine (ODA) under pseudofirst order conditions. The critical micelle concentration (CMC) of surfactant was determined by surface tension measurement. The effect of pH (2.5-4.5) and temperature (15-35°C) in the presence and absence of surfactant were investigated. Acti� vation parameters, ΔEa, ΔH # , ΔS # , ΔG ≠ , for the reaction were calculated by using Arrhenius and Eyring plot. Surface excess concentration (Γ max ), minimum area per surfactant molecule (A min ), average area occupied by each molecule of surfactant (a), surface pressure at the CMC (Πmax), Gibb's energy of micellization ( ), Gibb's energy of adsorption ( ), were calculated. It was found that the reaction in the presence of surfac� tant showed faster oxidation rate than the aqueous ethanol solution. Reaction mechanism has been deduced in the presence and absence of surfactant.

Solvent controlled synthesis of tin oxide nanocatalysts were prepared via the hydrothermal method. To study the effect of solvent on the particle size of tin oxide and their catalytic efficiency on photodegradation of environmental hazardous materials, the synthesis was carried out at different concentrations of solvent (isoamyl alcohol) keeping all other reaction conditions constant. The nanoparticles were characterized by FourierTransmission Infrared Spectroscopy, Scanning Electron Microscopy, Transmission Electron Microscopy, X-ray Diffraction and Thermogravimetric analysis. Prepared nanoparticles were applied as nanocatalyst under UV-visible light for the photodegradation of methyl green,which is an abundant organic pollutant of industrial waste water. Photodegradation activities of the nanocatalysts were measured in three different ways, i. pseudo first order rate constant, “k”. ii. percentage degradationand iii. degradation rate. Effect of solvent was quantitatively explained in term of double sphere model of ion-ion interaction. Degradation of pollutants was also monitored by High Performance Liquid Chromatography.

In this work, we report the formation of leaf-like ZnO nanoflakes by anodization of zinc foil in a mixture of ammonium sulfate and sodium hydroxide electrolytes under various applied voltage and concentration of sodium hydroxide. The morphology and structure of ZnO nanoflakes were investigated by field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy and X-ray diffraction analysis. In addition, the photocatalytic activity of the prepared nanoflakes zinc oxide was evaluated in the photodegradation of organic dye methylene blue (MB) solution under UV irradiation. It was found that zinc oxide prepared under high concentration of sodium hydroxide and high voltage showed better performance in the photodegradation of methylene blue.

Oxidation of sodium succinate in aqueous solution by potassium ferricyanide was investigated. The effects of different reaction parameters such as initial concentration of succinate, concentration of ferricyanide, and influence of metal ions (Zn+2, Ni+2, Cu+2, Cd+2) on the oxidation of succinate were investigated at 25 ± 0.05 °C. Large rate enhancements were observed in the redox reaction between succinate and ferricyanide with increasing concentrations of both oxidant and reductant. The kinetics results indicated that the succinate oxidation was significantly inhibited in the presence of metal ions. Pseudo first order rate constants values were found decreased with increase in concentrations of metal ions which reflected that inhibition rate was directly influenced with the metal ions concentration.

Gold (Au) nanoparticles supported on alumina (Al2O3) were prepared at several pH levels via the deposition-precipitation (DP) method. The effects of pH at below and above the isoelectric point (IEP) of Al2O3 as well as the pH adjustment before and after the addition of the support into the gold chloride solution were investigated. The results revealed the formation of cationic, clusters and metallic Au on alumina. The catalytic activity of these species was tested in the reduction of p-nitrophenol (p-NP) using hydrazine as a reductant. The catalytic reaction was monitored spectrophotometerically and the highest rate constant (k-) achieved based on pseudo first order kinetic model was 12.7 × 10-3 s-1. Structural and elemental characterizations of the supported gold nanoparticles were carried out using X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy-dispersive X-rays (EDX), atomic absorption spectrometry (AAS), and ultraviolet-visible spectroscopy (UV-Vis).

Calcium oxide (CaO) nanoparticles are known to exhibit unique property due to their high adsorption capacity and good catalytic activity. In this work the CaO nanocatalysts were prepared by hydrothermal method using anionic surfactant, sodium dodecyl sulphate (SDS), as a templating agent. The as-synthesized nanocatalysts were further used as substrate for the synthesis of alumina doped calcium oxide (Al2O3·CaO) nanocatalysts via deposition-precipitation method at the isoelectric point of CaO. The Al2O3·CaO nanocatalysts were characterized by FTIR, XRD, TGA, TEM, and FESEM techniques. The catalytic efficiencies of these nanocatalysts were studied for the photodegradation of 2,4,6-trinitrophenol (2,4,6-TNP), which is an industrial pollutant, spectrophotometrically. The effect of surfactant and temperature on size of nanocatalysts was also studied. The smallest particle size and highest percentage of degradation were observed at critical micelle concentration of the surfactant. The direct optical band gap of the Al2O3·CaO nanocatalyst was found as 3.3 eV.

A systematic study on the preparation of SnO2 nanoparticles using a simple sol-gel technique has been conducted by varying reaction parameters such as concentration of ammonia, ammonia feed rate and reaction temperature. The tin oxide obtained was characterized by using FTIR, BET, XRD and TEM. Particles size was obtained in the range of 4 to 5 6 nm and the surface area was found to be between 76 to 114 m(2) g(-1) depending on the reaction parameters. Meanwhile, the catalytic activity of SnO2 was first time investigated for the hydrogenation reaction of styrene using ethanol as the solvent at 70 degrees C and 1 atmospheric pressure It is found that SnO2 acts as a good catalyst in this hydrogenation process The product conversions in the presence of catalysts prepared at different conditions were between 37 to 72%.

The kinetics of the reaction between vitamin C ( l -ascorbic acid) and ferric chloride hexahydrate was investigated in acidic medium at pH 3 spectrophotometrically. The order of the reaction was established by applying different methods, such as initial rate method, integration method and half-life method. The results obtained from each method were correlated with each other and consistency in all methods was observed. The order of the reaction with respect to each reactant was found first and the overall second order was recommended for the reaction.