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Fe/CeO2–SiO2 nanocomposite was synthesized by using zwitterionic surfactant 3-(N,N-dimethyloctadecylammonio) propane sulfonate (SB3-18) by sol–gel and hydrothermal methods. The nanocomposite was well characterized before its use. X-ray diffraction (XRD) results confirmed the synthesis of the Fe/CeO2–SiO2 nanocomposite. Crystallite size calculated by using Scherrer equation was 5.33 nm while it was found 5.26 nm by Williamson–Hall equation. Bandgap of Fe/CeO2–SiO2 nanocomposite shows redshift after the doping of Fe. Degradation studies of methylene blue (MB) and chlorpyrifos (CP) were investigated by nanofiltration (NF) column under visible light irradiation. Degradation and adsorption of MB was investigated by three different types of columns under visible light irradiation. It was observed to achieve 100 % removal of MB and 91 % of CP through column in which rice husk ash (RHA) slurry was mixed with the nanocomposite.

Novel approach for the synthesis of Fe2O3-CuO-MoO3 nanocomposite was established using sol-gel and ultra-sonication setup. The conformation of the synthesized nanocomposite was done using Fourier transform-infrared spectroscopy (FTIR), X-ray diffraction (XRD), and scanning electron microscopy-energy dispersive X-ray (SEM-EDX) techniques. The chemistry of product thermal stability and decomposition was studied using thermo gravimetric analysis-differential scanning calorimetery (TGA-DSC) with respect to increase in temperature. The optical properties were studied using UV-visible spectroscopy via Wood and Tauc relation. XRD data indicates the presence of orthorhombic crystal system with crystallite size of 4.45 and 38.71 nm using Scherrer equation and Williamson-Hall equations, respectively. The particle size was calculated using transmission electron microscopy (TEM) and found to be 12.67 nm. The catalytic ability of synthesized nanocomposite was studied against methylene blue, and the decrease in percentage degradation from 5 to 30% was observed in nanocomposite prepared from sol-gel to ultra-sonication method.

An eco-friendly and economical, green synthesis method has been employed for the synthesis of iron-oxide (Fe2O3) nanoparticles by using orange peel extract as a stabilizing agent. The thermody-namic properties were evaluated using thermogravimetric analysis-diffraction scanning calorimetry (TGA-DSC), the formation of Fe2O3 nanoparticles was confirmed using fourier transform infra-red spectroscopy (FTIR), X-Ray diffraction (XRD) and scanning electron microscopy-energy dispersive X-ray (SEM-EDX) spectroscopy. The hydrodynamic diameter was observed using a dynamic laser scattering-particle size analyser (DLS-PSA). The green synthesized nanoparticles were used to evaluate their antibacterial activity via the agar well diffusion method against gram positive (Bacillus subtilis, Staphylococcus aureusb) and gram negative (Escherichia coli., Pseudomonas aeruginosa) bacteria while keeping benzalkonium chloride, chlorhexidine, hexachlorophene and phenol as controls.

The availability of water has become a serious concern globally, therefore, it is a need to use waste water by its treatment. This treated water can be used in various sectors e.g., agriculture, leather industry, textile industry and in chemical reactors etc. The oxides of semiconductor nanoparticles are effective catalyst which are used in wastewater treatment. Ethylene glycol is used in sol-gel method to synthesize NiO/ZnO nanocomposites. ZnCl2 along with NiCl2.6H2O were used as precursors during synthetization of NiO/ZnO nanocomposites. We used various techniques such as Thermogravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC), Fourier Transform Infrared Spectroscopy (FTIR) and particle size analysis for synthesis of the nanocomposites which confirm that these nanocomposites act as catalyst. Full Text

Gadolinium doped tin oxide–iron oxide nanoparticles (Gd/Fe1.727Sn0.205O3) were synthesized via sol–gel method followed by hydrothermal method. Ethylene glycol played the role of directing agent to control surface morphology. Physical and optical properties of Gd/Fe1.727Sn0.205O3 nanoparticles were studied as a function of calcination temperature. Characterization techniques like thermogravimetric analysis (TGA), fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), particle size analyzer (PSA), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV–Visible spectroscopy (UV–VIS), and four-point probe technique have been used to study the thermal degradation, kinetics, thermodynamic properties, structural analysis, surface morphology, optical and electrical properties of nanoparticles. Prominent peaks in FTIR spectra at 563, 418, and 542 cm−1 were observed for Fe–O, Sn–O, and Gd–O, respectively. The uncalcined nanoparticles follow first order kinetics and Freeman–Carrol method was applied for calculating the activation energy. It was observed that nanoparticles calcined at 700 °C have 8.9 nm particle size calculated with particle size analyzer, which is smallest among all and having band gap energy of 2.3 eV. SEM micrographs show hexagonal geometry. The dependence of electrical resistance on temperature shows that these nanoparticles possess semiconducting behavior. These nanoparticles can be used as cathode material for solid oxides fuel cells (SOFCs) application. The nanoparticles calcined at 700 °C showed highest power density of 83.27 W cm−2 at 650 °C with open current voltage of 0.793 V.

This work presents the synthesis of SnO2–SiO2 nanocomposite via sol–gel method using N‑dodecyl-N,N-dimethyl-3-ammonium-1-propanesulfonate (SB3-12) zwitterionic surfactant as a templating agent at room temperature. Rice husk was used as a source for preparation of SiO2 and doping of samarium (Sm) on tin oxide-silica (SnO2–SiO2) was done by hydrothermal method. Size, optical and catalytic properties of Sm/SnO2–SiO2 was found dependent on the doping of Sm. Coats-Redfern and Horowitz-Metzger’s models were used to investigate the kinetics and thermodynamic parameters. The Sm/SnO2–SiO2 nanocomposite was characterized by FTIR, XRD, TGA, TEM, SEM, EDX and particle size analyzer. The photocatalyic activity of prepared material was studied against methylene blue dye under irradiation of sunlight. It was found that Sm/SnO2–SiO2 nanocomposite has small size, reduced band gap and greater degradation capacity than SnO2–SiO2 nanocomposite. Dependence of crystallinity, dislocation density and specific surface area on the size of nanocomposite was also observed.

Fe/CeO2-SiO2 nanocomposite was synthesized via hydrothermal method. Bond length of nanocomposite was determined through FTIR analysis, while Raman analysis showed lattice relaxation of CeO2 phase in Fe/CeO2-SiO2. TEM, XRD and DLS-PSA revealed an increase in size of Fe/CeO2-SiO2 as compared to CeO2-SiO2 which was attributed to have more oxygen vacancies in CeO2 after doping of iron. Lattice contraction was also observed in some phases of CeO2 in Fe/CeO2-SiO2 nanocomposite as compared to CeO2-SiO2 nanocomposite. This contraction was used for determination of Fe content incorporated in CeO2 [1 1 1] phase. The band gap values of Fe/CeO2-SiO2 nanocomposite were found reduced after doping of Fe by factors of 0.62 and 0.55 eV, respectively. Photoluminescence study of the materials was carried out to study the different type of transitions occurring after absorption of electromagnetic radiation. Photoluminescence intensity at 2.12 eV was found enhanced after doping of Fe due to increased oxygen vacancy. Photocatalytic activity of the nanocomposites was studied with the degradation of chlorpyrifos pesticide. Keywords: Photoluminescence, Band gap, Doping, Oxygen vacancies, Lattice contraction, Photocatalysis

Sol-gel spin coating method have been used to deposit un-doped, La, and Sm-doped ZnO thin films on Si substrate. The influence of Sm and La doping content on various physical properties of ZnO thin films were investigated using x-ray diffraction, photoluminescence spectroscopy, spectroscopy ellipsometry, scanning electron microscope, and four point probe technique. X-ray diffraction analysis reveals that Sm and La ions were successfully incorporated in ZnO lattice and all the thin films are highly crystalline with hexagonal wurtzite structure. Photoluminescence spectroscopy spectra indicates that defect concentration increases on increase in Sm and La content. Refractive index, extinction coefficient and optical band gap were determined from spectroscopy ellipsometry technique. The optical bandgap of ZnO thin films shifts towards higher wavelength (red shift) on incorporating La and Sm because of which its absorption ability for visible portion of electromagnetic radiation increases. The micrographs obtained from scanning electron microscope reveals that morphology consists of wrinkle type structure; the density of the wrinkles seems to be dependent on the dopant concentration as well as on the type of dopant. Remarkable improvement in electrical conductivity have also been observed after doping. Sm- and La-doped ZnO thin films have shown better photocatalytic degradation efficiency for methylene blue under solar light irradiation.

Controllable release of nutrients in soil can overcome the environmental problems associated with conventional fertilizer. Here we synthesized mesoporous nanocomposite of Zinc aluminosilicate (ZnAl2Si10O24) via co-precipitation method. Oryza sativa L. husk was used as source of silica for making the synthesis process green and economical. The nanocomposite was subsequently loaded with urea to achieve the demand of simultaneous and slow delivery of both zinc and urea. The structural characterization of nanocomposite was done by FTIR, XRD, TGA, BET, SEM/EDX and TEM. The release of urea and zinc was investigated with UV–Vis spectrophotometry and atomic absorption spectroscopy, respectively, up to 14 days. It was noted that urea holding capacity of mesoporous ZnAl2Si10O24 nanocomposite over long period of time was increased as compared to bulk aluminosilicates, due to its high surface area (193.07 m2 g−1) and small particle size of (64 nm). Urea release was found highest in first 24 h because of excess of adsorption on nanocomposite and least at 14th day. Fertilizer efficiency was checked on Oryza sativa L. in comparison with commercial urea and results showed significantly higher yield in case of urea loaded ZnAl2Si10O24 nanocomposite.

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.

CeO2-SiO2 nanoparticles were synthesized by surfactant assisted via sol-gel process at variable pH 9, 10 and 11 by keeping constant temperature of 27 ± 2 °C. However, same method was adopted for synthesis of CeO2-SiO2 nanoparticles at higher temperature 70 ± 2 °C while pH of the solution was kept constant at 9. Prepared nanoparticles were characterized using FTIR, SEM-EDX, PL spectrophotometer, UV-Vis spectrophotometer, XRD and DLS-PSA. Influence of varying pH and temperature on particle size, band gap, oxygen vacancies and catalytic activity for degradation of chlorpyrifos pesticide was studied. It was found that increase in pH increased the particle size and band gap, however decreased the catalytic activity towards chlorpyrifos pesticide. It was observed that increase in temperature at constant pH 9 showed slight effects on above mentioned properties. CeO2-SiO2 nanoparticles prepared at pH 9 and at temperature 27 ± 2 °C were found to have lowest particle size and band gap with highest catalytic activity.

Polymeric iron nano-chloroquine phosphate (PINCP) was formulated through polyol method using ferrous ammonium sulphate and polyethylene glycol (PEG) in aqueous medium. The current study was aimed to synthesize chloroquine phosphate (CP) conjugated with polymer and metal oxides at nanoscale level. TEM and XRD studies showed that nanoparticles have particle size ≈ 10 nm. Conjugation of polymer and metal with CP was confirmed through GC-MS and FTIR.

Polymeric iron nano-chloroquine phosphate (PINCP) was formulated through polyol method using iron precursor and polyethylene glycol (PEG) at nanoscale. Delayed release profile and evaluation of its toxic activity were determined. PINCP has found entrapment efficiency of 99.9% and drug contents of 27.7%. PINCP was found less toxic than commercial available chloroquine phosphate, while studying hemolytic effect. Antibacterial activity was also studied and nanodrug was observed active against gram positive bacterial agents.

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.

Temperature dependence of the structural, thermodynamic, and optical properties of MoO3 nanoparticles synthesized using sol–gel and sonication methods were studied. MoO3 nanoparticles showed variation in crystallite shape from hexagonal to orthorhombic and crystallite size in the range 3.05–5.21 nm with bandgap in the range 4.11–4.36 eV with change in the calcination temperature and the method of synthesis. Rietveld refinement of the X-ray diffraction (XRD) data confirmed the crystallite phase transition with space group PE and Pbnm with change in the lattice parameter ratio. Activation energy was calculated using XRD and TGA–DSC (thermogravimetry–differential thermal analysis) data and was found to be close to 4 kJ/mol. The bandgap fluctuation was due to the size dependence of the blue shift, which indicates strong quantum confinement due to the Bohr radius effect. Optical parameters such as the extinction coefficient, refractive index, optical conductivity, dielectric functions, and Urbach energy were calculated and found to depend on electron–phonon interactions.

The structural, optical and catalytic properties of undoped (CuO–ZnO) and CdS doped CuO–ZnO (CdS/CuO–ZnO) nanoparticles were studied. The blue shifting of optical band gap in CuO–ZnO nanoparticles as compared to their respective bulk oxides (CuO: 1.21–1.5 eV, ZnO: 3.37 eV) was observed as 3.9 eV, while red shifting after doping of CdS was found from 3.9 to 3.7 eV. The angle of diffraction and FWHM values were used to observe crystallite phase and to calculate crystallite size (using Scherer and Williamson–Hall equations) and other parameters like strain, dislocation density and bond length of nanoparticles. The particle size of CuO–ZnO and CdS/CuO–ZnO nanoparticles using transmission electron microscopy (TEM) was found 12.54 and 6.93 nm, respectively. It was concluded that decrease in particle size cause red shifting which increase the catalytic efficiency of nanoparticles.

Silica xerogel was extracted from the Rice Husk Ash (RHA) through alkaline extraction method. SnO2-SiO2 and Fe doped SnO2-SiO2 nanocomposites were synthesized via sol-gel and hydrothermal methods respectively using zwitterionic surfactant i.e., N-dodecyl-N,N-dimethyl-3-ammonio-1-propane sulfate (SB3-12). Coats-Redfern method was used to determine the activation energy, enthalpy, entropy, Gibb’s free energy and pre-exponential factor for thermal degradation of nanocomposite using TGA data. The optical properties of nanocomposites were studied and band-gap was measured using Wood and Tauc expression. The red shift was observed in Fe doped SnO2-SiO2 nanocomposite having band gap of 5.2 eV. It was found that smaller bandgap of Fe doped SnO2-SiO2 photocatalyst resulted a prominent increase in photocatalytic activity of nanocomposite against Methylene Blue (MB) under illumination of sunlight.

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.

In the current study, XRD peak profile analysis, optical and catalytic properties of pure ZnO–NiO and CdS doped ZnO-NiO nanocomposites were investigated. Average crystallite size, strain, dislocation density and bond length were determined with X-ray peak profile analysis. Optical properties such as band gap, extinction coefficient, refractive index, optical conductivity, and dielectric constants were studied by solid phase spectroscopy (SPS). The blue shift was observed in ZnO–NiO as compare to bulk ZnO due to the quantum confinement while red shift was found in CdS/ZnO–NiO nanocomposites as compare to ZnO–NiO nanocomposites is due to bulk defects inducing delocalization and pressure induced effect. The optical conductivity of ZnO–NiO nanocomposites was observed increased with doping of CdS on ZnO–NiO from 4.57 × 1018 to 6.71 × 1018 S–1, respectively. It was observed that catalytic efficiency depends on the particle size and band gap of the nanocomposites.

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).

We investigate the composition of 63 C2-C10 nonmethane hydrocarbons (NMHCs), methane (CH4) and carbon monoxide (CO), in Jeddah, Mecca, and Madina (Saudi Arabia), in Lahore, (Pakistan), and in Singapore. We established a database with which to compare and contrast NMHCs in regions where ambient levels and emissions are poorly characterized, but where conditions are favorable to the formation of tropospheric ozone, and where measurements are essential for improving emission inventories and modeling. This dataset will also serve as a base for further analysis of air pollution in Western Saudi Arabia including, but not limited to, the estimation of urban emissions and long range pollution transport from these regions. The measured species showed enhanced levels in all Saudi Arabian cities compared to the local background but were generally much lower than in Lahore. In Madina, vehicle exhaust was the dominant NMHC source, as indicated by enhanced levels of combustion products and by the good correlation between NMHCs and CO, while in Jeddah and Mecca a combination of sources needs to be considered. Very high NMHC levels were measured in Lahore, and elevated levels of CH4 in Lahore were attributed to natural gas. When we compared our results with 2010 emissions from the MACCity global inventory, we found discrepancies in the relative contribution of NMHCs between the measurements and the inventory. In all cities, alkenes (especially ethene and propene) dominated the hydroxyl radical (OH) reactivity (k OH) because of their great abundance and their relatively fast reaction rates with OH.

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.

The influence of calcination temperature on the photocatalytic activity of quaternary metal oxide nanocomposite i.e. gadolinium (Gd) doped cobalt tin oxide (CoSnO3) have been explored. The synthesis of nanocomposite material was completed in two steps using a novel method. The synthesized nanocomposite material was subjected to various characterization techniques like thermogravimetric analysis (TGA), X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), particle size analyzer (PSA), UV–Visible and photoluminescence spectroscopy in order to investigate its thermal, structural, and optical properties. The crystallite size, particle size and optical band gap estimated via XRD, PSA and UV–Visible spectroscopy, respectively reveals an increasing trend with calcination temperature. The Gd doped CoSnO3 nanocomposite material is found to be very efficient visible light photocatalyst. The photo-degradation efficiency in the presence of sunlight in degrading methylene blue and methyl orange is more than 90%. An insight mechanism of electron/hole trapping using electronic configuration has also been explored.

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.

We report growth of quaternary Cu2 ZnSnS4 (CZTS) thin films prepared by the electrochemical deposition from salt precursors containing Cu (II), Zn (II) and Sn (IV) metals. The influence of different sulfurization times t (t = 75, 90, 105 and 120 min) on the structural, compositional, morphological and optical properties, as well as on the electrical properties is studied. The films sulfurized 2 hours showed a prominent kesterite phase with a nearly stoichiometric composition. Samples were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM) and Raman and UV-VIS-NIR spectrometer at different stages of work. X-ray diffraction and Raman spectroscopy analyses confirmed the formation of phase-pure CZTS films. (FESEM) shows that compact and dense morphology and enhanced photo-sensitivity. STEM - EDS elemental map of CZTS cross-section confirms homogeneous distribution. From optical study, energy gap was enlarged with a changed sulfurization times in the range of 1.37–1.47 eV.

Surface of La/SnO2–TiO2 nanocomposite was modified during its synthesis using zwitterionic (3 (N-N dimethyloctadecyl ammonia) propane sulfonate), anionic (sodium dioctyl sulfosuccinate) and cationic (dimethyl dioctadecyl ammonium chloride) surfactants by sol gel method followed by reflux method. Effect of surfactants on morphology was investigated with scanning electron microscopy. Crystallite size was determined by using XRD pattern with the help of Scherrer and Williamson Hall equations, while particle size was calculated through transmission electron microscopy. Optical properties as well as photocatalytic activity was investigated against degradation of methylene blue under sun light. It was found that doping of lanthanum enhanced the photocatalytic activity of SnO2–TiO2 nanoparticles. A direct relation between particle size and band gap was found while both have inverse relationship with degradation and lattice strain.