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Influence of pyrolytic temperature on optoelectronic properties and the energy harvesting applications of high pressure TiO2 thin films
摘要： The present work deals with the development of a novel photocatalyst to decompose most of the organic pollutants. This work provides a strategy for reproducible high-pressure phases of TiO2 at ambient conditions through nebulizer spray pyrolysis (NSP) technique by varying the substrate temperatures of 200–500 °C using titanium (IV) isopropoxide as a titanium precursor. The structural, morphological, optical and electrical properties of the deposited TiO2 thin films were investigated by using X-ray diffraction, field emission scanning electron microscopy, UV–Visible spectroscopy, Hall effect and temperature dependent resistivity measurements, respectively. The structural analysis confirms that the films deposited at higher substrate temperature are crystallized in TiO2–II phase having polycrystalline nature with good crystalline quality and also pressure induced amorphous phases were also observed for the films deposited at lower substrate temperatures. Deposited films have the uniform surface with homogeneity and porous nature which is suitable for enhanced photocatalytic applications. Electrical measurements show that the films are having n-type behavior with appreciable carrier mobility and concentration. The use of high-pressure TiO2-II phase for higher photocatalytic efficiency was demonstrated.
关键词： Photocatalytic,Methylene blue,TiO2-II phase,Spray pyrolysis
更新于2025-09-23 15:22:29
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Characterization of a novel silicon-containing hybrid polymer by thermal curing, pyrolysis behavior, and fluorescence analysis
摘要： A novel linear silicon-containing hybrid polymer with C C and Si H linkages, diphenyl-dihydroethynyl-silane (DPHES), had been conveniently synthesized and well characterized. The thermal curing, crosslinked structure and pyrolysis behavior were studied by DSC, Fourier transform infrared (FTIR), and Pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). The results suggest the crosslinked structures consist mainly of phenyl and aromatic fused rings, which are formed through cyclotrimerization, addition reaction, and hydrosilylation reaction. The thermal properties indicate that the crosslinked DPHES exhibits excellent thermal stability with the temperature at 5% weight loss are higher than 572 and 509 (cid:1)C under nitrogen and air atmosphere, respectively. The ?uorescence emission spectra show DPHES and its crosslinked product also have moderate ?uorescence properties, emitting purple light, and visible blue light, respectively, which further veri?ed the structure of DPHES. These results suggest that DPHES has the potential to be used as light-emitting materials with excellent thermal properties.
关键词： silicon-containing hybrid polymer,?uorescence property,pyrolysis behavior,thermal curing
更新于2025-09-23 15:22:29
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H2 gas sensor based on PdOx-doped In2O3 nanoparticles synthesized by flame spray pyrolysis
摘要： In this work, 0–1.0 wt% PdOx-doped In2O3 nanoparticles were successfully synthesized by flame spray pyrolysis (FSP) in a single step for the first time and investigated for gas-sensing applications. The sensing films were fabricated by spin coating and tested towards hydrogen (H2) at various temperatures ranging from 150 to 350 °C in dry air. The powder and sensing film properties were analyzed by X-ray analyses, nitrogen adsorption and electron microscopy. The spherical and cubic In2O3 nanoparticles with diameters ranging from 2 to 20 nm were observed with no apparent secondary phase of Pd or PdOx. Detailed analyses suggested that Pd species might be in the form of PdOx crystallites embedded in and on grain boundaries of In2O3 nanoparticles. From gas-sensing measurements, hydrogen-sensing characteristics of In2O3 nanoparticles were significantly improved by PdOx doping particularly at the optimal Pd content of 0.50 wt%. The optimal PdOx-doped In2O3 sensing film showed a high response of 3526 towards 10,000 ppm H2 at the optimal working temperature of 250 °C. In addition, PdOx doped In2O3 sensing films displayed good stability and high H2 selectivity against various toxic and flammable gases including H2S, NO2, C2H4O, C2H4, C2H5OH and C2H2.
关键词： Flame spray pyrolysis,PdOx doped In2O3,H2 sensor,Semiconducting metal oxide
更新于2025-09-23 15:22:29
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Role of polysiloxanes in the synthesis of aligned porous silicon oxycarbide ceramics
摘要： The present work focuses on establishing the role of polysiloxane precursors in the synthesis of aligned porous polymer derived silicon oxycarbide ceramics. The precursors used for the synthesis are, polymethylhydrosiloxane, vinyl terminated polydimethylsiloxane and cyclic tetramethyl-tetravinlycyclotetrasiloxane. Hydrotalcite is used for attaining aligned macroporosity during the crosslinking stage itself. Subsequently, pyrolysis of the sample has been carried out to synthesize the ceramics. The evolution of pore structure in these PDCs during the crosslinking and pyrolysis is co-related to the thermal decomposition behaviour. The pore morphology, structure and the size were analyzed using SEM, X-ray computed tomography and BET. Our studies confirm the presence of bimodal porosity in these PDCs. These PDCs have a specific surface area ranging from 77 - 160 m2/g and a total pore volume ranging from 0.18 - 0.29 cm3/g. These results could be significant for achieving a controlled synthesis process of porous materials suitable for various applications like adsorption, filtering and electrochemical storage.
关键词： Mesoporous,X-Ray computed tomography,Pyrolysis,Polymer derived ceramics,Specific surface area
更新于2025-09-23 15:22:29
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Structural, morphological and transport properties of nanostructured La1-Sr Co0.2Fe0.8O3- thin films, deposited by ultrasonic spray pyrolysis
摘要： The main aim of this study is to improve the electrochemical properties of LaFeO3-δ perovskite as cathode by strontium and cobalt doping in lanthanum and iron sites. Ultrasonic spray pyrolysis (USP) following sintering process in air was utilized to synthesize La1-xSrxCo0.2Fe0.8O3-δ (LSCF) with 0 ≤ x ≤ 0.4. X–ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM) and impedance spectroscopy techniques were used to study the structure, surface morphology and transport properties of the deposited films. Contrary to what might expect, up to x = 0.4, single orthorhombic phase of La1-xSrxCo0.2Fe0.8O3-δ have been obtained for all deposited films. Impedance spectroscopy results at intermediate temperatures (500–700 °C) indicated that by increasing of strontium, the conductivity increases, and activation energy decreases from 0.41 eV for x = 0–0.24 eV for x = 0.4.
关键词： IT-SOFC,LSCF,Ultrasonic spray pyrolysis
更新于2025-09-23 15:22:29
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Effect of Magnesium Substitution on the Structural, Morphological, Optical and Wettability properties of Cobalt Ferrite Thin Films
摘要： Cobalt ferrite thin films with magnesium substitution (Co1-xMgxFe2O4 for 0.0 ≤ x ≤ 1.0) were grown on clean glass substrate with dimensions (75 mm × 25 mm × 1.45 mm) using spray pyrolysis method. The grown thin films were annealed at 500°C for 4 h and further used for structural, morphological, optical and surface wettability investigations. The structural characterizations of the prepared films were performed through X-ray diffraction (XRD) technique at room temperature. The analysis of the XRD pattern shows the formation of single phase cubic spinel structure of the films. The most intense peak (311) of the XRD pattern was used to estimate the average crystallite size. The obtained crystallite size varies between 16 nm to 19 nm confirming the nanocrystalline nature of the films. The lattice constant calculated from XRD data show decreasing nature from 8.386 ? to 8.365 ? with increase in magnesium content x. The variation of X-ray density with magnesium content x shows initial increasing nature and then decreasing nature. Metal cation active vibration modes, metal oxygen stretching and bending vibrations were confirmed through the Raman analysis. Surface morphology of the films was studied by using scanning and transmission electron microscopy (SEM and TEM) technique. Observations of SEM micrographs reveal that particles are in nanosize dimensions and almost distributed uniformly. Particle size calculated from TEM analysis was found to be in the range of 5-18 nm. The band gap of the films was measured by UV-VIS spectrophotometer. It is observed that, the energy band gap decrease from 2.83 eV to 2.37 eV as increase in magnesium substitution. The Photoluminescence study showed the characteristic near-band-edge emission of presently investigated films samples at around 710 nm. The contact angle measurements revealed the hydrophilic nature of all the thin films under investigation.
关键词： CoFe2O4,spray pyrolysis,SEM-TEM,thin films,Mg2+ substitution,PL
更新于2025-09-23 15:21:21
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Structural Properties of (Sn1?xMgxO) Thin Films and Optical Parameter Dependence with Gamma Ray Irradiation
摘要： Tin-Magnesium oxide (Sn1?xMgxO) thin films were prepared on glass substrates using the chemical spray pyrolysis technique, whereupon the samples were irradiated by gamma rays using a Co-60 radioactive source. X-ray diffraction showed that all prepared films were polycrystalline in nature with a tetragonal structure and a preferential growth of crystallites in the (110) plane. In general, the average crystallite size, lattice constants, dislocation density and crystallite density decreased with increasing Mg doping from 0% to 8%. Further, atomic force microscopy showed that the thin films were smooth and homogenous. The optical properties were obtained by ultraviolet–visible spectrophotometry, and the transmittance and absorbance spectra before and after gamma ray irradiation were compared for all samples, whereby the absorption and extinction coefficients and real and imaginary parts of the dielectric were studied before and after irradiation. It was found that the energy band gap values decreased from 3.94 eV to 3.72 eV with increasing Mg doping from 0% to 8% before irradiation, and from 3.92 eV to 3.59 eV after irradiation. All optical constants increased with doping percentage before and after irradiation. Energy-dispersive x-ray spectroscopy showed that all structures contained Sn and O elements in the undoped state, and contained SnO2 and Mg in the doped state.
关键词： doping,SnO2 thin films,gamma ray,energy-dispersive x-ray technology,chemical spray pyrolysis,structural properties
更新于2025-09-23 15:21:21
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Orthogonal gas sensor arrays by chemoresistive material design
摘要： Gas sensor arrays often lack discrimination power to different analytes and robustness to interferants, limiting their success outside of research laboratories. This is primarily due to the widely sensitive (thus weakly-selective) nature of the constituent sensors. Here, the effect of orthogonality on array accuracy and precision by selective sensor design is investigated. Therefore, arrays of (2–5) selective and non-selective sensors are formed by systematically altering array size and composition. Their performance is evaluated with 60 random combinations of ammonia, acetone and ethanol at ppb to low ppm concentrations. Best analyte predictions with high coefficients of determination (R2) of 0.96 for ammonia, 0.99 for acetone and 0.88 for ethanol are obtained with an array featuring high degree of orthogonality. This is achieved by using distinctly selective sensors (Si:MoO3 for ammonia and Si:WO3 for acetone together with Si:SnO2) that improve discrimination power and stability of the regression coefficients. On the other hand, arrays with collinear sensors (Pd:SnO2, Pt:SnO2 and Si:SnO2) hardly improve gas predictions having R2 of 0.01, 0.86 and 0.28 for ammonia, acetone and ethanol, respectively. Sometimes they even exhibited lower coefficient of determination than single sensors as a Si:MoO3 sensor alone predicts ammonia better with a R2 of 0.68.
关键词： Ethanol,WO3,SnO2,Electronic nose,Ammonia,Gas sensor,Acetone,Flame spray pyrolysis,MoO3
更新于2025-09-23 15:21:21
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Analysis on different detection mechanisms involved in ZnO-based photodetector and photodiodes
摘要： The present study reports on the comparison between the ultraviolet (UV) light detection mechanisms in ZnO-based photodetectors and ZnO/PEDOT:PSS hybrid photodiodes. Using spray pyrolysis method, ZnO thin films were deposited upon glass substrates. The deposition temperature was varied from 350 to 425 °C and the physical properties of ZnO thin films were investigated. The structural analysis reveals that all the prepared ZnO thin films have a preferred orientation along the (002) plane with hexagonal wurtzite structure. The morphological analysis reveals that the grains are uniformly distributed. Electrical properties reveal that the ZnO thin film deposited at 425 °C shows a higher carrier concentration of 3.76 × 1016 cm?3 with low electrical resistivity value of 2.59 × 102 ? cm. For fabrication of UV photodetectors, the optimum ZnO layer with good electrical and optical property was deposited on ITO substrate with substrate temperature maintained at 425 °C. For the fabrication of hybrid UV photodiodes, poly (3,4 ethylene dioxythiophene):poly (styrene sulphonate) (PEDOT:PSS) and zinc oxide (ZnO) was used as the hole and electron transporting layers, respectively. The current–voltage (I–V) and photoresponse switching characteristics under UV light of the fabricated ZnO-based photodetector and photodiodes were studied and the detection mechanisms of such devices were analysed. It was observed that the ZnO-based photodiodes show higher photoresponsivity (R) value of 0.25 A/W with fast photoresponse switching speed.
关键词： UV light detection,PEDOT:PSS,ZnO,photodetector,spray pyrolysis,photodiodes
更新于2025-09-23 15:21:01
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One-step spray of Cu2NiSnS4 thin films as absorber materials for photovoltaic applications
摘要： A simple one-step ?Spray Pyrolysis? technique was developed for preparing Cu2NiSnS4 (CNTS) thin film followed by an annealing treatment process. Originally, the spray technique was successfully used to deposit the thin film onto glass substrate at 250 °C for 60 min spray duration. Again, the deposited thin film was annealed in a sulfur atmosphere at a temperature of 500 °C during 30 min. The sulfured thin film exhibits (111), (220) and (311) orientations correspond well to the cubic CNTS structure and other impurity compounds. The SEM data exhibit a uniform, rough and compact topography of CNTS thin films with an average-thickness of 1.36 μm. The absorption coefficient is found to be higher than 104 cm?1 in the visible region while the direct band energy of 1.62 eV, which is eminently suitable for use as an absorber in the solar cell. The complex impedance diagrams indicate the decrease of resistance by increasing temperature, which attributes to a semiconductor behavior. The close values of activation energies 0.63 and 0.54 eV determined from both angular frequency and DC conductivity indicate that the carrier transport mechanism is thermally activated.
关键词： Cu2NiSnS4,Photovoltaic applications,Spray Pyrolysis,Semiconductor behavior,Thin films
更新于2025-09-23 15:21:01