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Highly transparent Nitrogen doped Titanium dioxide (N-TiO2) thin films are deposited onto glass/FTO substrates at optimized substrate temperature 450°C by using a simple chemical spray pyrolysis technique. The N-TiO2 thin films are characterized for their photoelectrochemical, structural, morphological and optical properties using PEC, XRD, SEM, and UV-Vis. spectrophotometer. The PEC study shows that both short circuit current (Isc) and open circuit voltage (Voc) for the doping concentration at 1.5 at. % are relatively maximum (Isc = 0.72 mA and Voc = 520 mV). X-ray diffraction studies show that films are polycrystalline with a tetragonal crystal structure. The scanning electron micrograph shows that the films are uniform, compact and with randomly distributedgrain size varying from 20 to 60 nm. The observed direct band gapsare about 3.4 and 3.37 eV for typical TiO2 and N-TiO2 thin films respectively.

In present article, WO3 thin films have been successfully synthesized by chemical spray pyrolysis approach. The effect of spraying quantity of solution onto the photoelectrochemical (PEC), structural, morphological, and optical properties has been studied. Film prepared at 40 ml solution quantity shows the excellent photoelectrochemical performance (Isc= 0.69 mA/cm2 and Voc = 0.64 V) in 0.05 M concentrated H2SO4 electrolyte. X-ray diffraction studies reveal that the synthesized WO3 thin films are polycrystalline with monoclinic crystal structure. The chief vibrational modes of the WO3 sample, located at 712.64 and 804.28 cm−1 corresponding to the stretching and the bending of O W O bond respectively and are consistent with a monoclinic structure. The estimated band gap energy of WO3 thin films varies from 2.37 to 2.45 eV with respect to quantities of spraying solution and it exhibits absorption in visible region. Film shows a maximum specific surface area of 31.63 m2/g. Photoelectrocatalytic degradation of brilliant blue dye in aqueous solutions is studied. The end result shows that the degradation percentage of brilliant blue using WO3 photoelectrode has reached 92% under visible light illumination after 240 min. The enhancement in photoelectrocatalytic activity of optimized 40 ml WO3 sample is mainly due to the suppressed the recombination rate of photogenerated electron–hole pairs. This study provides an effective WO3 photoelectrode for removing of organic pollutants present in the water.

The need to utilize TiO2 based metal oxide hetero nanostructures for the degradation of environmental pollutants like Rhodamine B and reactive red 152 from the wastewater using stratified WO3/TiO2 catalyst under sunlight illumination. WO3, TiO2 and stratified WO3/TiO2 catalysts were prepared by a spray pyrolysis method. It was found that the stratified WO3/TiO2 heterostructure has high crystallinity, no mixed phase formation occurs, strong optical absorption in the visible region of the solar spectrum, and large surface area. The photocatalytic activity was tested for degradation of Rhodamine B (Rh B) and reactive red 152 in an aqueous medium. TiO2 layer in stratified WO3/TiO2 catalyst helps to extend its absorption spectrum in the solar light region. Rh B and Reactive red 152is eliminated up to 98 and 94% within the 30 and 40 min respectively at optimum experimental condition by stratified WO3/TiO2. Moreover, stratified WO3/TiO2 photoelectrode has good stability and reusability than individual TiO2 and WO3 thin film in the degradation of Rh B and reactive red 152. The photoelectrocatalytic experimental results indicate that stratified WO3/TiO2 photoelectrode is a promising material for dye removal.

Highly crystalline Cu 2 ZnSnS 4 (CZTS) thin films have been deposited onto glass and FTO coated glass substrates by simple chemical spray-pyrolysis technique. It is an important material for solar energy conversion through the both photovoltaics and photocatalysis. The effect of substrate temperatures on the physico-chemical properties of the CZTS films is studied. The XRD study shows the formation of single phase CZTS with kesterite structure. FE-SEM analysis reveals nano flakes architecture with pin-hole and crake free surface with more adherent. The film deposited at optimized substrate temperature exhibits optical band gap energy of 1.90 eV, which lies in the visible region of the solar spectrum and useful for photocatalysis application. The photoelectrocatalytic activities of the large surface area (10 × 10 cm 2 ) deposited CZTS thin film photocatalysts were evaluated for the degradation of sugarcane factory wastewater under visible light irradiation. The results show that the CZTS thin film photocatalyst exhibited about 90% degradation of sugar cane factory wastewater. The mineralization of sugarcane factory wastewater is studied by measuring chemical oxygen demand (COD) values.

In the present work, layered WO3/ZnO thin films have been prepared by simple chemical spray pyrolysis method. As prepared films are characterized by photoelectrochemical (PEC) solar cell, X-ray diffraction (XRD), Raman spectroscopy, Field emission scanning electron microscopy (FE-SEM), Brunauer–Emmer–Teller (BET) and energy dispersive X-ray spectroscopy techniques. XRD analysis reveals the formation of hexagonal and monoclinic phases of ZnO and WO3 respectively. Raman analysis confirms the formation of layered WO3/ZnO thin films. FE-SEM images demonstrate that the surface morphology of layered WO3/ZnO consists of nano balls like morphology. The specific surface area of the layered WO3/ZnO thin film is found to be 65.12 m2 g−1. The photoelectrocatalytic degradation properties of layered WO3/ZnO thin films were investigated by studying degradation of sugarcane factory wastewater. The end result shows that the degradation percentage of sugarcane factory wastewater using layered WO3/ZnO photo electrode has reached 94.44% after 100 min. under sunlight illumination.

In the present work, stratified WO 3 /ZnO thin films have been prepared by simple chemical spray pyrolysis technique. The structural, morphological, compositional and photoelectrocatalytic properties of the stratified WO 3 /ZnO thin films are studied. The photoelectrochemical (PEC) study shows that, both short circuit current (I sc ) and open circuit voltage (V oc ) are (I sc = 1.023 mA and V oc = 0.980 V) relatively high at 40 ml spraying quantity of ZnO solution on pre-deposited WO 3 thin films. XRD analysis reveals that stratified WO 3 /ZnO thin films are polycrystalline with monoclinic and hexagonal crystal structures for WO 3 and ZnO respectively. The specific surface area of the stratified WO 3 /ZnO thin film is found to be 48.12 m 2 g −1 . The enhanced photoelectrocatalytic activity of stratified WO 3 /ZnO is mainly due to the suppressing the recombination of photo generated electron-hole pairs. The end result shows that the degradation percentage of phthalic acid (PA) using stratified WO 3 /ZnO photo electrode has reached 63.63% after 320 min. under sunlight illumination. The amount of mineralization of phthalic acid is studied with the help of chemical oxygen demand (COD) measurement.

Layered WO3/TiO2 thin films have been deposited onto glass and FTO coated glass substrates using spray pyrolysis method. The structural, morphological, compositional and photocatalytic properties of layered WO3/TiO2 thin films are studied. The photoelectrochemical (PEC) study shows that, both short circuit current (Isc) and open circuit voltage (Voc) are (Isc = 0.575 mA and Voc = 0.485 V) relatively high at 15 ml spraying quantity of TiO2 solution on pre-deposited WO3. SEM images show that the substrate surface is well covered with a uniform and round shaped TiO2 nanoparticles. The AFM images show the rough nature of the film. The specific surface area of the layered WO3/TiO2 thin film is found to be 62.14 m2 g−1. Photoelectrocatalytic degradation of benzoic acid (BA) in aqueous solutions is studied. The end result shows that the degradation percentage of BA using layered WO3/TiO2 photoelectrode has reached 46.56% under sunlight illumination after 320 min. The amount of degradation is confirmed by COD analysis.

The WO 3 and stratified WO 3 /TiO 2 thin films are successfully prepared by the spray pyrolysis method. The structural, morphological, compositional and photoelectrocatalytic properties of WO 3 and stratified WO 3 /TiO 2 thin films are studied. XRD analysis confirms that films are polycrystalline with monoclinic and tetragonal crystal structures for WO 3 and TiO 2 respectively. The SEM images clearly show 3D sheeted porous structure of the as-prepared TiO 2 forms on WO 3 in stratified WO 3 /TiO 2 samples. The synthesized photoelectrodes was used as catalyst for photoelectrocatalytic degradation of oxalic acid in aqueous medium. The rate constant (k) was evaluated as a function of the initial concentration of species. A significant decrease in concentrations of organic species was observed from COD analysis. The photoelectrocatalytic degradation effect is relatively higher in the case of the stratified WO 3 /TiO 2 than WO 3 thin film photoelectrode in the degradation of oxalic acid and 83% removal efficiency of oxalic acid is obtained after 180 min. Based on the obtained experimental data, the possible photoelectrocatalytic reaction mechanism was proposed. The photoelectrocatalytic experimental results indicate that stratified WO 3 /TiO 2 photoelectrode is the promising material for removing of water pollutants.

Zinc oxide (ZnO) thin films have been deposited with ultrasonic rinsing assisted modified successive ionic layer adsorption and reaction (M-SILAR) method. The effect of Zn concentration on the growth of ZnO films and power conversion efficiency (PCE) of dye-sensitized solar cells (DSSCs) have been studied. The surface morphology changes from nanorods to the nanoflowers like structure as a result of coalescence of the nanorods. Also, the significant effect of the dye adsorption time of photoelectrodes on the overall PCE of ZnO based DSSCs has been investigated systematically. It is found that the chemical stability is the foremost issue for ZnO photoelectrode. The prolonged dye adsorption time is responsible for the deterioration of the ZnO nanostructure due to the formation of Zn2+/N3 dye aggregates. The DSSC prepared using photoelectrode of 0.1 M Zn concentration and dye loading time of 18 h exhibited a highest PCE of 0.70%, since it possesses well-defined 1D nanostructure which facilitates very low reverse saturation current density and longer electron lifetime.

Thin film of carbon was synthesized from camphor (C10H16O) by CVD technique in hydrogen atmosphere. For the first time it is confirmed the presence of almost zero indirect band gap in addition to its direct band gap.. Carrier concentration with intrinsic carbon is found to be around 1021 n/cm3. It is suggested that unless the zero indirect band gap is  increased carbon thin film   cannot be used for making a p:n junction. XRD, Raman and SEM analysis are performed.

The Ni0.4Zn0.6Fe2O4 ferrite, BaTiO3 ferroelectric and Ni0.4Zn0.6Fe2O4–BaTiO3 bilayered magnetoelectric thin films have been synthesized onto the quartz substrates at optimized substrate temperatures (400, 250 °C) using the simple spray pyrolysis technique. These films were characterized for their structural, morphological, dielectric and magnetic properties. The XRD studies reveal that the films are polycrystalline in nature with spinel cubic structure. The morphological study shows the formation of agglomerated cubes like grains. The dielectric constant and dielectric loss is measured as a function of frequency in the frequency range 20 Hz–1 MHz. Impedance spectroscopy is used to study the electrical behavior of these thin films. The saturation magnetization of Ni0.4Zn0.6Fe2O4 ferrite and Ni0.4Zn0.6Fe2O4–BaTiO3 bilayered thin films are 141 and 111 emu cm−3, respectively. The value of magnetoelectric voltage obtained for Ni0.4Zn0.6Fe2O4–BaTiO3 bilayered thin films is about 221 mV.

WO3 thin films have been deposited onto glass and FTO coated glass substrates using a simple chemical spray pyrolysis technique. The structural, morphological, optical and photocatalytic properties of WO3 thin films are studied. The photoelectrochemical (PEC) study shows that, both short circuit current (Isc) and open circuit voltage (Voc) are (Isc=0.38 mA and Voc=0.59 V) relatively higher at 300 °C substrate temperature. The structure and morphology of WO3 thin films are studied by X-ray diffraction (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM). XRD study reveals that the films are polycrystalline in nature with monoclinic crystal structure. SEM images show that the substrate surface is covered with a uniform and grain like morphology. The AFM images show the rough nature of the film. The structure and local symmetry of the film are studied with the help Raman spectroscopy. The chief vibrational modes of the WO3 sample, located at 805, 715 and 269 cm−1 corresponding to the stretching and the bending of O–W–O bond respectively and are consistent with a monoclinic structure and the low-frequency peaks are observed at 269 and 325 cm−1 can be assigned due to the bending δ (O\W\O) vibrations in monoclinic structure. Photoelectrocatalytic degradation of methyl orange (MO) dye in aqueous solutions is studied. The end result shows that the degradation percentage of methyl orange (MO) using WO3 photoelectrode has reached 98% under visible light illumination after 320 min. The amount of degradation is confirmed by COD and TOC analysis.

A combination of photocatalysis and biodegradation is a promising approach for the removal of xenobiotic organic compounds from wastewater, since photocatalysis cleaves the molecules into simpler intermediates that are later mineralized by microorganisms. Sequential photocatalytic and biological treatment (SPABT) consisting of ZnO as a photocatalyst and a microbial consortium (Galactomyces geotrichum and Brevibaccilus laterosporus) enhanced the degradation of a model textile dye, methyl red (MR). SPABT completely decolorized 500 mg MR/L within 4 h. Biotreatment alone required 6 h for 100% decolorization. A maximum of 70% decolorization was achieved with the photocatalytic treatment but reductions in COD and toxicity were not adequate. Significant elevated activities of enzymes, including azo reductase, laccase and veratryl alcohol oxidase, were observed in the microbial consortium after exposure of MR. The degradation pathway and products of MR varied with treatment applied. The persistent azo bond was cleaved by following photocatalytic treatment with the microbial biotreatment. Tests with Sorghum vulgare and Phaseolus mungo indicated the products obtained by SPABT were non-phytotoxic.

The solution combustion synthesis is a novel approach to synthesize the nanocrystalline materials with an unexpectedly high surface to volume ratio. Thus, in present paper, La 0.6 Sr 0.4 Co 0.8 Fe 0.2 O 3− δ powders have been synthesized by solution combustion synthesis route at different fuel to oxidant ratio ( ψ ) and its effect on different physiochemical properties have been studied. The mode of propagation of combustion reaction changed from smoldering to volume with increasing ψ . The thermal analysis shows that exothermicity increased with ψ resulting into enhanced agglomeration as confirmed from particle size distribution. Typically, the size of agglomerate varies from 0.59 to 1.56 μm. The XRD and FT-IR patterns reveal that the phase pure La 0.6 Sr 0.4 Co 0.8 Fe 0.2 O 3−δ is formed at the ψ =2. The TEM particles size is 25 nm. La 0.6 Sr 0.4 Co 0.8 Fe 0.2 O 3−δ powder shows the higher catalytic activity at about 426 °C.

WO3 thin films have been deposited using simple chemical spray pyrolysis technique and successfully applied as photoanode for photoelectrocatalytic degradation of methylene blue. The films were deposited on bare glass and fluorine doped tin oxide coated glass substrates to study photoelectrochemical (PEC) properties, crystal structure, surface morphology, chemical composition and optical studies. The PEC results indicate that, the films deposited at 300 °C show the improved the photocurrent response relative to other deposited thin films. The monoclinic crystal structure of WO3 has been confirmed from X-ray diffraction studies. The Raman spectra of optimized films show two strong peaks at 271.34 and 327.27 cm−1 can be assigned to the bending δ (O\W\O) vibrations in the monoclinic WO3 structure. Field emission scanning electron microscopy showed that the film surface constituted of aggregates of very small seed like nanoparticles. UV–vis spectrophotometry shows that the WO3 film deposited at the 300 °C shows a band gap of ~2.66 eV and has emerged as one of the visible light photocatalysts, which can absorb light below 520 nm wavelength. The photocatalytic degradation of methyl blue has been investigated in aqueous solution. The removal of the color and decrease of UV–Visible absorbance was simultaneously able to show the oxidation of methylene blue dye.

The performance of solid oxide fuel cells (SOFCs) is hampered by the large polarization and ohmic losses across the cathode–electrolyte interface. To minimize these losses, in most SOFCs the cathode is obtained by thick-film deposition techniques. Since the properties of such films depend upon the starting materials and screen-printing parameters, the effect of the mesh opening diameter on the physiochemical properties of cathodes for intermediate-temperature (IT)-SOFCs has been studied. Combustion-synthesized La0.6Sr0.4Co0.2Fe0.8O3−δ powder with specific surface area of 11.64 m2 g−1 was utilized in film formation. All films were porous in nature, and the thickness was observed to increase with the mesh opening diameter. The electrical conductivity showed a decreasing trend with film thickness. Typically, film with 7 μm thickness showed moderate conductivity of 16.4 S cm−1 with Ea = 0.1 eV.

Nowadays, the commercialization of solid oxide fuel cell (SOFC) is impeded by the chemical compatibility and polarization losses in association with electrode/electrolyte interface. Thus, to minimize these difficulties, the thick film of LSCF-GDC (50:50 wt%) composite was deposited onto GDC electrolyte to form perfect LSCF-GDC/GDC structure. The chemically compatibility of LSCF-GDC upon sintering of 1000 °C was confirmed from the X-ray diffraction studies. Typically, the film with 15 μm thickness possesses the porous structure, availing the free path for oxygen diffusion. The electrochemical impedance analysis of symmetric cell with LSCF-GDC as an electrode implies the relaxation of charge transfer and electrochemical reduction reaction with temperature. The NiO-GDC (30:70 wt%) supported SOFC with GDC and LSCF-GDC as an electrolyte and cathode, respectively was tested for their performance. The cell generates the maximum powder density of 315 μWcm−2 at 500 °C.

A large difference in thermal expansion coefficient of electrode and electrolyte leads to imperfect electrode/electrolyte interface and hence significant polarization losses in solid oxide fuel cells. To overcome the difficulties associated with electrode and electrode/electrolyte interface, there is need to fabricate the composite cathode. Thus the present paper deals with study of La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3− δ (LSCF)–Ce 0.9 Gd 0.1 O 1.95 (GDC) nanocomposite with different fractions of GDC obtained by physical mixing of combustion synthesized nanopowders. No secondary phases were observed upon sintering at 1100 °C for 2 h affirming the chemical compatibility between LSCF and GDC. The composites with relatively high GDC% have higher density as a consequence of rapid grain growth and less conductivity. The nanocomposite with 50% of GDC showed electric conductivity of 30 Scm −1 at 500 °C and low area specific resistance of 106 Ω cm 2 with 10 μs relaxation time at 200 °C.

WO3 thin films have been deposited onto glass and FTO coated glass substrates using simple chemical spray pyrolysis technique. The effect of solution concentration on the photoelectrochemical (PEC), structural, morphological and photoelectrocatalytic properties has been investigated. The structure and morphology of WO3 photoelectrodes are studied by X-ray diffraction (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM). The PEC study shows that both open circuit voltage (Voc) and short circuit current (Isc) at the optimized solution concentration (0.125 M) are relatively maximum (Isc = 0.62 mA and Voc = 0.58 V). XRD study reveals that the films are polycrystalline in nature with monoclinic crystal structure. SEM images show that the substrate surface is well covered with uniform, compact and fine grain like morphology. The AFM image shows the rough nature of the film. Photoelectrocatalytic degradation of methyl red dye in aqueous solutions is studied. The end result shows that the degradation percentage of methyl red using WO3 photoelectrode has reached 97 % under visible light illumination after 160 min. The amount of mineralization is confirmed by COD and TOC analysis.

Graphical abstract: The Ni{sub x}Zn{sub 1−x}Fe{sub 2}O{sub 4} (where x = 0.0, 0.2, 0.4, 0.6, 0.8, 1.0) thin films were prepared by spray pyrolysis technique onto the quartz substrates. The composition x = 0.4 shows the formation of the compact grain structure and highest saturation magnetization of 143 emu/cm{sup 3}. - Highlights: • Synthesis of nanocrystalline Ni{sub x}Zn{sub 1−x}Fe{sub 2}O{sub 4} thin films. • Influence of Ni substitution on physicochemical properties. • Electrical conductivity arises mainly from the grain boundary. • The highest saturation magnetization is 143 emu/cm{sup 3} for x = 0.4. - Abstract: The Ni{sub x}Zn{sub 1−x}Fe{sub 2}O{sub 4} thin films have been prepared using a simple spray pyrolysis technique. The X-ray diffraction studies reveal that, the films are polycrystalline with spinel structure. The lattice parameters vary in the range of 8.35–8.48 A with composition (x) obeying Vegard’s rule. SEM and AFM studies show that the surface of the films exhibit a smooth, compact and a pin hole free morphology. Raman spectra indicate first order Raman active modes; A{sub 1g} (λ = 334 cm{sup −1}); E{sub g} (λ = 148 cm{sup −1}) and T{sub 2g} (λ = 699) of the Ni{sub x}Zn{sub 1−x}Fe{sub 2}O{sub 4}. The investigation onmore » dielectric constant, dielectric loss tangent and ac conductivity was carried out in the frequency range 20 Hz–1 MHz at room temperature. The linear nature of the AC conductivity shows small polaron type of hopping mechanism. The saturation magnetization increases up to x = 0.4 (143 emu/cm{sup 3}), which decreases for higher x.« less

The BaCe0.8Y0.2O2.9 (BCY) is co-doped with Zr and Gd with a motive to improve its chemical stability and electrical conductivity. The films are spray deposited on alumina substrate. The films annealed at different temperatures are studied by XRD, XPS, FTIR, Raman and SEM/AFM. The annealing is observed to promote crystallinity, grain growth and densification. The XRD pattern reveals orthorhombic crystal structure. The presence of Ce(IV) and other elements is confirmed by XPS and EDAX, which also assures absence of surface impurities. The most intense band at 355 cm−1 is observed in micro Raman spectrum. The morphology of the film changes with the annealing. AFM reveals grains of 51 nm. The electrical conductivity of BCZYG is measured in air and moist air and it is compared with that of BC, BCY, BCZY and BCGY. Among all, BCZYG shows highest conductivity of 10.02 × 10−3 S cm−1 in moist-air.

Doped barium cerate is a promising solid electrolyte for intermediate temperature fuel cells as a protonic conductor. In the present paper, the nanocrystalline Gd-doped barium cerate (BaCe0.7Gd0.1Y0.2O2.9) thin films have been successfully deposited on alumina substrate by spray pyrolysis technique. The films deposited from 0.1 M concentration and annealed at five different temperatures were characterized with different physio-chemical techniques. The BCGY is crystallized in orthorhombic perovskite structure with slight shift to the lower 2θ value compared with barium cerate (BC) and yttrium doped barium cerate (BCY). The grain growth and hence densification is also investigated by using SEM and AFM. The grain growth is almost complete at 1000 °C and the surface of the film appears to be smooth with typical roughness of 152 nm. Raman spectrum of BCGY film shows intense band at 463.8 cm−1 compared to pure BC and BCY indicating the presence of more oxygen vacancies due to Gd doping. The proton conductivity of BCGY thin film in moist atmosphere is 1×10−3 Scm−1.

20 % yttrium doped barium cerate (BCY20) powder has been synthesized by cost effective solution combustion method and the effect of oxidant to fuel ratio on the structural morphological and electrical properties is reported. The phase formation and evolution is studied by using XRD. The carbonate free orthorhombic BCY20 phase is obtained for optimum oxidant to fuel ratio. The microstructure of the pellets sintered at 1573 K is examined through scanning electron microscopy and also with transmission electron microscopy. The vibrational modes are detected by Raman spectroscopy. The presence of Ba, Ce and Y is confirmed with elemental analysis. The dc conductivities of sintered pellets measured in air atmosphere at 873 K are 1.6 × 10−3, 2 × 10−3 and 1.9 × 10−3 S/cm for fuel lean, optimum and rich ratio respectively.

Transparent TiO 2 thin films have been sucessfully synthesized by chemical spray pyrolysis technique. The effect of substrate temperature on the photoelectrochemical (PEC), structural, morphological, optical and photoelectrocatalytic properties has been investigated. The PEC study shows that both short circuit current ( I sc ) and open circuit voltage ( V oc ) at the optimized substrate temperature (450 °C) are relatively maximum ( I sc =1.7 mA and V oc =770 mV). The tetragonal crystal structure has been confirmed from X-ray diffraction patterns. FE-SEM study reveals that the film surface is changed from nanogranular to nanorod like morphology. The films exhibit a transmittance of about 80% in the visible region and a sharp absorption edge at 375 nm corresponding to the fundamental absorption edge in UV region. Band gap energy varies from 3.33 to 3.43 eV with substrate temperature. Electron-phonon coupling present in TiO 2 films has been analyzed using Raman spectroscopy. The elemental composition and valence states of TiO 2 film are studied by using X-ray photoelectron spectroscopy. The effect on the photoelectrocatalytic behavior of the large surface area (64 cm 2 ) TiO 2 photocatalyst samples were studied by using photoelectrocatalytic degradation of benzoic acid under UV light illumination.

In present paper, La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3− δ (LSCF)/Ce 0.9 Gd 0.1 O 1.95 (GDC)/LSCF structure has been studied to understand electrode/electrolyte interface. The nanocrystalline powder required for screen printing was obtained through solution combustion synthesis with glycine as a fuel. The LSCF powder synthesized at fuel to oxidant ratio of two is calcined at 900 °C as TG–DTA reveals thermal stability only beyond 900 °C. The X-ray diffraction pattern of calcined powder demonstrates rhombohedral perovskite structured LSCF with 27 nm crystallite size. However, dynamic laser scattering shows 0.9 μm sized agglomerates while TEM shows 74 nm particles. For potential application in solid oxide fuel cells, the temperature programmed reduction and oxidation were done on the LSCF. The results exhibit strong reduction and oxidation behavior around 860 and 388 °C, respectively. The cell with LSCF as an electrode shows minimum charge transfer resistance of 6.3 Ω cm 2 at 550 °C.

The nanocrystalline BaCe0.7Zr0.1Y0.2O2.9 (BCZY) thin films have been deposited on alumina substrate by simple and economic spray pyrolysis technique. The spray deposited films were annealed at different temperatures and were characterized by different physio-chemical techniques. The XRD studies revealed orthorhombic structured BCZY thin films with little shift in 2θ compared to BCY. The crystallite size and grain size were observed to enhance with annealing temperature. The grain growth was completed by 1000 °C and compact structure was obtained at 1100 °C. Evolution of the surface microstructure and roughness of the BCY and BCZY thin films is done using AFM. Raman spectra of BCZY and BCY exhibits pronounced characteristic band at 359 and 353.25 cm−1 respectively. The proton conductivity of BCZY thin film in moist atmosphere was 0.83 × 10−3 S cm−1 at 400 °C.

ZnFe 2 O 4 thin films are successfully deposited onto bare and fluorine doped tin oxide (FTO) coated quartz substrate using the spray pyrolysis method. The structure and morphology of ZnFe 2 O 4 photoelectrodes were studied by X-ray diffraction (XRD) and atomic force microscopy (AFM). The X-ray diffraction pattern confirms the polycrystalline nature of films with a spinel cubic crystal structure. The AFM micrographs shows the granular nature of the films. The dielectric constant and dielectric loss shows dispersion behavior as a function of frequency measured in the range from 20 Hz to 1 MHz. Photoelectrocatalysis degradation of salicylic acid using ZnFe 2 O 4 photoelectrode under sunlight illumination has been investigated. The result shows that the degradation percentage of salicylic acid on ZnFe 2 O 4 photoelectrodes is reached 49% under neutral conditions after 320 min illumination. The decrease in values of COD from 19.4 mg/L to 6.4 mg/L indicates there is mineralization of salicylic acid with time.

Curie temperature of Co 0.7− x Ni x Mn 0.3 Fe 2 O 4 (with X =0.00, 0.05, 0.10 and 0.15) synthesized by the double sintering ceramic method, was recorded by, Lorria Sinha (T CL ), dc resistivity ( T CR ) and dielectric measurement ( T CD ). Curie temperatures obtained by three various methods are in good agreement with each other. Curie temperature measurements exhibit anomalous increasing trend with increasing nickel content for all the compositions. Three - sublattice model is used to elucidate anomalous behavior as, Neels two - sublattice model fails to explain increase in Curie temperature, even after the replacement of Co 2+ ions (3 µB) by Ni 2+ ions (2 µB). Decrease in lattice constant and interionic distances can be probably originated by strengthening of A–B interaction. Enhancement in Curie temperature is observed due to the strengthening of A–B interaction. Values of magnetic moments and interaction between them are not the only reasons for enhancement of T c but change in their orientation with temperature is also important and therefore analysis of Curie temperature is given on basis of anisotropic energy.

Photoelectrocatalytic degradation of typical aromatic compounds with persistent reaction rate is studied using thin layers of N-titanium dioxide deposited on transparent and conducting glass substrates. Backside illuminated flow-through parallel plate photoelectrochemical reactors is used and electrical bias for suppressing charge carrier recombination is applied externally. The degradation experiments are performed under solar irradiation with the conditions aimed at reducing contaminant concentrations to maximal tolerated levels as specified under environmental regulations. From the observed COD–time relations, rate constants normalized to unit volume and photocurrent (kinetic parameters), characterizing the efficiency of the electrochemical oxidation process involving photogenerated valence band holes or their immediate reaction products, are calculated and compared to the decrease of optical extinction of the solutions. The parameters for salicylic acid, 4-chlorophenol, benzoic acid and oxalic acid are found to decrease as the main absorption peaks of these substances diminish in due course of degradation reaction. In order to realize a complete mineralization of such compounds, which should be an ultimate aim of water purification, COD and TOC is analyzed.

The Fe 2 O 3 , Au:Fe 2 O 3 , TiO 2 /Fe 2 O 3 and TiO 2 /Au:Fe 2 O 3 thin films are successfully prepared by the spray pyrolysis technique at an optimised substrate temperature of 400 °C and 470 °C, respectively onto amorphous and F:SnO 2 coated glass substrates. The effect of TiO 2 layer onto photoelectrochemical (PEC), structural, optical and morphological properties of Fe 2 O 3 , Au:Fe 2 O 3 , TiO 2 /Fe 2 O 3 and TiO 2 /Au:Fe 2 O 3 thin films is studied. The PEC characterization shows that, maximum values of short circuit current ( I sc ) and open circuit voltage ( V oc ) are ( I sc = 185 μA and V oc = 450 mV) are at 38 nm thickness of TiO 2 . Deposited films are polycrystalline with a rhombohedral and anatase crystal structure having (1 0 4) preferred orientation. SEM and AFM images show deposited thin films are compact and uniform with seed like grains. The photocatalytic activities of the large surface area (64 cm 2 ) TiO 2 /Au:Fe 2 O 3 thin film photocatalysts were evaluated by photoelectrocatalytic degradation of industrial wastewater under sunlight light irradiation. The results show that the TiO 2 /Au:Fe 2 O 3 thin film photocatalyst exhibited about 87% and 94% degradation of pollutant in sugarcane and textile industrial wastewater, respectively. The significant reduction in COD and BOD values from 95 mg/L to 13 mg/L and 75 mg/L to 11 mg/L, respectively was also observed.

The 20 % yttrium doped barium cerate (BCY20) powder has been synthesized by cost effective solution combustion method. The flame temperature measured by pyrometer was 1055 °C, less than the adiabatic temperature due to various losses. The phase formation and evolution was studied with TG-DTA and XRD. The carbonate free orthorhombic BCY20 phase was obtained upon calcination at 900 °C. The microstructure of the powders and sintered pellet was examined through scanning electron microscopy. The vibrational mode at 355 cm, characteristics of CeO6 octahedra, was detected in Raman while the bands corresponding to M-O vibrations were revealed in FT-IR. The dc conductivities of sintered pellet measured in argon and air atmospheres at 600 °C were 1.53 × 10−3 and 1.41 × 10−3 S/cm.

Undoped and Al doped ZnO (AZO) thin films are successfully prepared by spray pyrolysis technique at optimised substrate temperature of 400 °C onto amorphous and F:SnO2 coated glass substrates. Effect of Al doping on structural, morphological and optical properties of ZnO thin films is studied. Deposited films are polycrystalline with a hexagonal (wurtzite) crystal structure having (0 0 2) preferred orientation. The PEC characterization shows that, short circuit current (Isc) and open circuit voltage (Voc) are (Isc = 0.38 mA and Voc = 421 mV) relatively higher at the 3 at.% Al doping. SEM images show deposited thin films are compact and uniform with seed like grains. All films exhibit average transmittance of about 82% in the visible region and a sharp absorption onset at 375 nm corresponding to 3.3 eV. The photocatalytic activities of the large surface area (64 cm2) Al-doped ZnO photocatalyst samples were evaluated by photoelectrocatalytic degradation of phthalic acid under UV light irradiation. The results show that the 3 at.% AZO thin film photocatalyst exhibited degradation of phthalic acid up to about 45% within 3 h with significant reduction in COD and TOC values.

The Fe 2 O 3 thin films have been deposited using ferric trichloride precursor at an optimized substrate temperature and concentration by simple chemical spray pyrolysis technique. Effect of quantity of the spraying solution on physicochemical properties of Fe 2 O 3 thin films has been studied. Photoelectrochemical technique was used to optimize the quantity of a spraying solution. The PEC study shows that, Fe 2 O 3 films are photoactive with relatively higher values of I sc =34.2 μA and V oc =190 mV respectively at 50 ml quantity (thickness ~239 nm). Effects of thickness on crystalline structure, morphology and optical properties have been studied. X-ray diffraction study confirms that the films are polycrystalline with rhombohedral crystal structure. The SEM and AFM micrographs depicts that the films are compact and needle shaped grains with grain size ~160–250 nm. The direct band gap energy of Fe 2 O 3 thin films is found to be in the range of 2.16–2.47 eV. Four characteristic luminescence peaks having near band-edge, violet, blue and green emission are observed in the photoluminescence spectra. Photocatalytic degradation of benzoic acid by using Fe 2 O 3 photoelectrode under visible light illumination has been investigated. The amount of mineralization is confirmed by COD and TOC analysis.

Ni x Zn 1− x Fe 2 O 4 ferrite has been synthesized by the ceramic method using Ni CO 3 , ZnO, Fe 2 O 3 precursors. The influence of Ni content on the structural, morphological, electrical and magnetic properties of Ni x Zn 1− x Fe 2 O 4 ferrites is studied. The X-ray diffraction (XRD) analysis reveals that the samples are polycrystalline with spinel cubic structure. The SEM images of Ni x Zn 1− x Fe 2 O 4 ferrite show that the grain size decreases with an increase in the Ni content. The tetrahedral and octahedral vibrations in the samples are studied by IR spectra. Frequency dependence of dielectric constant shows dielectric dispersion due to the Maxwell–Wagner type of interfacial polarization. Conduction mechanism due to polarons has been analyzed by measuring the AC conductivity. Impedance spectroscopy is used to study the electrical behavior. Magnetic properties of Ni x Zn 1− x Fe 2 O 4 are studied by using hysteresis loop measurement. The maximum value of saturation magnetization of 132.8 emu/g obtained for the composition, x =0.8, is attributed to magnetic moment of Fe 3+ ions.

Yttrium doped barium cerate (BCY) a solid state ion conductor which exhibits proton conductivity under proper atmospheric conditions, is used as an electrolyte in a solid oxide fuel cell (SOFCs). In present work, nanocrystalline BaCe 0.8 Y 0.2 O 2.9 (BCY20) thin films were successfully deposited onto alumina substrates by simple and economical spray pyrolysis technique (SPT) at 250 °C. The effect of solution concentration and annealing on physico-chemical properties of BCY20 thin film has been studied. The X-ray diffraction (XRD) studies of spray pyrolysed BCY20 films revealed polycrystalline (crystallite size 35 nm) orthorhombic structure with lattice parameters a = 8.77 A, b = 6.234 A and c = 6.223 A. The scanning electron micrographs showed dense morphology which is very useful for electrolyte. The stoichiometry was confirmed by elemental analysis and the estimated atomic ratio was in good agreement with that of the precursor solution ratio. The most intense band at 353.26 cm −1 observed in room temperature Raman spectrum of BCY20 film was due to vibrational mode of barium cerate. The FTIR spectra with heat treatment shows no carbon based vibration bonds, revealing absence of carbon based surface impurities in the sample. The dc conductivities measured in air and argon atmospheres at 600 °C were 1.7 × 10 −3 and 4.25 × 10 −3 S cm −1 , respectively.

The crack free, homogeneous, nanocrystalline La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3 thin films have been deposited on Ce 0.9 Gd 0.1 O 1.95 electrolyte by the spray pyrolysis technique. The films with typically 1–2 μm thickness, get crystallized on annealing at 800 °C. In the present work, the effect of substrate temperature on microstructure, crystallization and conductivity has been systematically studied. The deposition of film at 300 °C shows higher in plane electrical conductivity of 26.6 S cm −1 with activation energy, E a = 0.23 eV. The higher conductivity attributes to uniform, thin and dense microstructure of thin films. No interfacial reaction products between La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3 and Ce 0.9 Gd 0.1 O 1.95 were detected upon annealing at 800 °C/4 h. The uniformity and porosity distribution as a function of deposition temperature clarified from Scanning Electron micrograph.

The photoelectrocatalytic degradation of selected aromatic phenols and acids, amongst them substances of environmental concern like bisphenol-A (BPA), ethyl-paraben and phthalic acid, was studied on thin layers of semiconducting titanium dioxide deposited on transparent, electrically conducting substrates. A module of nine backside solar illuminated flow-through parallel plate photoelectrochemical reactors was used and electrical bias for suppressing charge carrier recombination was applied. The progress of oxidative degradation on the illuminated semiconductor electrode was followed by UV/vis absorption and COD (chemical oxygen demand) analysis. From the latter, kinetic data were calculated and compared on the basis of apparent first-order rate constants, related to current efficiencies which reflect the competition between solute and solvent (water) oxidation. The efficiencies (COD based) for 4-chlorophenol, salicylic acid, benzoic acid, phthalic acid, ethyl-paraben, BPA, p-cresol and 4-methoxyphenol as well as model compounds for aliphatic transient species in the course of the degradations – acetate, oxalic acid and maleic acid, lie between 10 and 70 M−1, a rather narrow range illustrating the rather unspecific oxidation on TiO2, which can be ascribed to the high redox potential of light generated oxidizing species. In many cases, these values are close to values obtained from the decrease of UV absorption of bands characteristic for the aromatic system. Long time irradiation experiments using solar light yielded conversion efficiencies of up to 90 percent in batch recirculation mode.

Thin films of iron oxide are synthesized by spray pyrolysis technique using ferric chloride as precursor in non-aqueous medium. The effect of solution concentration onto photochemical, structural, morphological, optical, luminescence and thermal properties has been investigated. Structural analysis confirms the rhombohedral crystal structure with strong (1 1 0) orientation. Raman spectrum reveals that the deposited films contain α-phase of Fe 2 O 3 (hematite). The SEM images of optimized Fe 2 O 3 thin films show microneedle like structure with varying grain size from 75 to 120 nm. The observed direct band gap is about 2.0 eV for Fe 2 O 3 thin film. Room temperature photoluminescencespectra showed three pronounced emission peaks for all concentrations. The photocatalytic oxidation of Rhodamine B with hematite Fe 2 O 3 thin films under solar illumination is investigated. The first order rate constants for this heterogeneousphotocatalysis are evaluated as a function of the initial concentration of Rhodamine B (RhB). The extent of mineralization of degraded sample is confirmed by total organic carbon (TOC) andchemical oxygen demand (COD)analysis. This work suggests that prepared iron oxide photoelectrodes demonstrate an excellent ability to remove toxic dyes from industrial wastewater.

Dynamic magnetoelectric voltage measurements of 30 % Co0.7−xNixMn0.3Fe2O4:70 % Pb(Zr0.52Ti0.48)O3 composites with x = 0.00, 0.05, 0.10, 0.15 synthesized by ceramic method were carried out by linear and quadratic method. Maximum linear magnetoelectric coefficient (α) of 14.7 mv Oe−1 cm−1 and maximum quadratic coefficient (β) of 2.26 × 10−4 mv Oe−2 cm−1 were obtained for composition with x = 0.05. Maximum values of α and β for composition with x = 0.05 may be due to more connectivity between grains than in other compositions observed from scanning electron micrographs. Higher values of dielectric constant and ac conductivity for particular composition could also be possible reasons for maximum magnetoelectric coefficients. Smaller dielectric loss at higher frequencies was observed for the same composition which may result into less leakage of charges consequently increasing the resultant magnetoelectric coefficients.

Li-doped ZnO thin films with preferred (0 0 2) orientation have been prepared by spray pyrolysis technique in aqueous medium on to the corning glass substrates. The effect of Li-doping on to the photoelectrochemical, structural, morphological, optical, luminescence, electrical and thermal properties has been investigated. XRD and Raman study indicates that the films have hexagonal crystal structure. The transmittance, reflectance, refractive index, extinction coefficient and bandgap have been analyzed by optical study. PL spectra consist of a near band edge and visible emission due to the electronic defects, which are related to deep level emissions, such as oxide antisite (OZn), interstitial zinc (Zni), interstitial oxygen (Oi) and zinc vacancy (VZn). The Li-doped ZnO films prepared for 1 at% doping possesses the highest electron mobility of 102 cm2/Vs and carrier concentration of 3.62 × 1019 cm−3. Finally, degradation of 2,4,6-Trinitrotoluene using Li-doped ZnO thin films has been reported.

Tin doped zinc oxide thin films are synthesized by simple chemical spray pyrolysis onto glass substrates using zinc acetate and stannic chloride precursors in an aqueous medium. The influence of tin doping onto photoelectrochemical, structural, morphological, optical, electrical and impedance properties have been investigated. Structural analysis confirms the hexagonal (wurtzite) structure of deposited films with crystal reorientation effect. SEM micrographs depict the films are rough, adherent and homogeneous with varying grain size (average grain size ∼100–300 nm). Contact angle measurement shows that the films are hydrophilic in nature. Valence states of constituent elements in ZnO host lattice are analyzed by X-ray photoelectron spectroscopy. Direct band gap of the films decreases with tin doping up to 3.19 eV. The highest electrical conductivity (0.95 Ω−1 cm−1 and carrier concentration (8.94 × 1017 cm−3) and lowest mobility (6.64 cm2 V−1 s−1) is observed at 1.5 at.% tin doping. We studied interparticle interactions like grains, grain boundary effects using complex impedance spectroscopy.

This article provides the current research activities that concentrate on the role of hydroxyl radicals in heterogeneous photocatalysis by transition metal oxides for different nanostructures. We devote most attention to Al-based Fe2O3 nanostructures that have been synthesized using chemical methods. The visible light photocatalytic activity of nanocrystalline pure and Al-based Fe2O3 photocatalysts for degradation of Salicylic acid, 4-Cholorphenol, and Acid orange 7 (Azo dye) is reported. The catalytic activity and selectivity for organic species are remarkably influenced by the size of the different photocatalyst. Utilization of various structures, advanced oxidation processes, heterojunction between Al-based Fe2O3 and TiO2, and application of solar energy for heterogeneous photocatalysis of water impurities were discussed. Extent of complete mineralization of such compounds by measuring COD and TOC was discussed. We conclude this review with personal perspectives on the directions towards which future r...

The performance of CZTS thin films deposited by using pulsed laser deposition technique is investigated as a function of target composition. The chemical composition ratio a = Cu/(Zn + Sn) of the target material has been varied from 0.8 to 1.2 in step of 0.1 by keeping Zn/Sn constant. The effect of the chemical composition in the precursor thin films on the structural, morphological, chemical and optical properties of the CZTS thin films has been investigated. X-ray diffraction and X-ray photoelectron spectroscopy studies showed that the annealed CZTS thin films are of a single kesterite crystal structure without any other secondary phases. The direct band gap energy of the CZTS thin films is found to decrease from 1.72–1.53 eV with increase of ‘a’. The estimated band-gap energy from the quantum efficiency measurements is about 1.54 eV. The solar cell fabricated with Glass/Mo/CZTS/CdS/ZnO:Al/Al structure grown using [a = Cu/(Zn + Sn) = 1.1] showed the best conversion efficiency of 4.13% with Voc = 700 mV, Jsc = 10.01 mA/cm2 and FF = 0.59.

The photocatalytic degradation of wastewater with ZnO based photocatalysts under solar illumination has been investigated. Advanced oxidation processes such as photoelectrocatalysis, sonolysis and H2O2 treatment show promise in eliminating the dangers of exposure to wastewater and the products of their natural breakdown. A basic understanding of the mechanistic details involved in the oxidative transformations remains the key for improving the effectiveness of the advanced oxidation processes. The role of hydroxyl radical in the breakdown of the wastewater is elucidated through determining the degradation rates, analyzing transformation intermediates and studies using computational chemistry methods. In order to realize a complete mineralization of wastewater COD, BOD and TOC analysis has been carried out.

Zinc oxide (ZnO) thin films have been deposited onto fluorine doped tin oxide coated glass substrates by economical chemical spray pyrolysis technique. Films were deposited using various quantities of solution from 50 to 200 cc (substrate temperature 400°C, solution concentration 0·2M) in order to achieve different thicknesses. The films were characterised by X-ray diffraction, SEM, AFM and optical absorption techniques. The films exhibit a hexagonal wurtzite crystal structure with preferred (002) orientation. Morphological study showed a smooth and nanocrystalline surface of ZnO films. Direct optical band gap energy of ZnO thin films is found to be 3·24 eV. The average transmission is of the order of 87% in the visible region. The photoelectrocatalytic response of the film against Escherichia coli Davis is studied using a specially designed photoelectrochemical (PEC) reactor module. Thickness and UV light dependent photoelectrocatalytic bactericidal properties of ZnO thin films have been investig...

Ga-doped ZnO thin films are synthesized by chemical spray pyrolysis onto corning glass substrates in aqueous media. The influence of gallium doping on to the photoelectrochemical, structural, Raman, XPS, morphological, optical, electrical, photoluminescence and thermal properties have been investigated in order to achieve good quality films. X-ray diffraction study depicts the films are polycrystalline and fit well with hexagonal (wurtzite) crystal structure with strong orientations along the (0 0 2) and (1 0 1) planes. Presence of E 2 high mode in Raman spectra indicates that the gallium doping does not change the wurtzite structure. The coupling strength between electron and LO phonon has experimentally estimated. In order to understand the chemical bonding structure and electronic states of the Ga-doped ZnO thin films XPS analysis have been studied. SEM images shows the films are adherent, compact, densely packed with hexagonal flakes and spherical grains. Optical transmittance and reflectance measurements have been carried out. Room temperature PL spectra depict violet, blue and green emission in deposited films. The specific heat and thermal conductivity study shows the phonon conduction behavior is dominant in these polycrystalline films.

The conventional zirconium based yttria stabilized zirconia (YSZ) electrolyte has been synthesized from aqueous solution by cost effective air atomized spray pyrolysis technique (SPT). The films show well developed dense, nanocrystalline material. The thermal analysis of zirconyl nitrate reveals the possibility of crystalline YSZ film formation only above 400 °C, which is confirmed from the XRD pattern. The activation energy of 1.14 eV clarifies its conductivity behavior, verified from DC and AC conductivity measurements.

N-doped ZnO (NZO) thin films are synthesized via spray pyrolysis technique in aqueous medium treating zinc acetate and N,N-dimethylformamide as precursors. Influence of N doping on structural, optical and luminescence properties have been investigated. Films are nanocrystalline having hexagonal crystal structure. Raman analysis depicts an existence of N Zn O structure in NZO thin film. XPS spectrum of N 1s shows the 400 eV peak terminally bonded, well screened molecular nitrogen (γ-N 2 ). Lowest direct band gap of 3.17 eV has been observed for 10 at% NZO thin film. The UV, blue, and green deep-level emissions in photoluminescence of NZO films are due to Zn interstitials and O vacancies.

Thin films of highly textured ZnO are synthesized by simple chemical spray pyrolysis onto corning glass substrates in aqueous medium. The influence of solution concentration onto photoelectrochemical, structural, morphological, compositional, optical, electrical and thermal properties have been investigated. Structural analysis shows the hexagonal (wurtzite) crystal structure. Electron–phonon-coupling in ZnO films has analyzed using Raman spectroscopy. The chemical composition and valence states of constituent elements in ZnO are analyzed by X-ray photoelectron spectroscopy. The SEM and AFM micrographs depict the films are compact and homogeneous (hexagonal platelets nanostructures) with varying grain sizes (average grain size ∼50–150 nm). The specific heat and thermal conductivity study shows the phonon conduction behavior is dominant in these polycrystalline films.