The photocatalytic decomposition of an eco-persistent AO7 dye with sunlight in an oxygenated aque- ous suspension has been studied under a nano-crystalline hexagonal ZnO photocatalyst. The effect of substrate temperat...The photocatalytic decomposition of an eco-persistent AO7 dye with sunlight in an oxygenated aque- ous suspension has been studied under a nano-crystalline hexagonal ZnO photocatalyst. The effect of substrate temperature on the structural, morphological and photoactive properties has been investigated. The degradation of the AO7 dye is achieved using a photoelectrochemical reactor module equipped with ZnO synthesized electrodes. Kinetic parameters have been investigated in terms of a first order rate equation. The rate constant for this hetero- geneous photocatalysis was evaluated as a function of the initial concentration of original species. A substantial reduction in AO7 dye is achieved as analyzed from COD and TOC studies. The mechanism for the degradation could be explained on the basis of the Langmuir-Hinshelwood mechanism.展开更多
Transparent conducting antimony doped tin oxide （Sb：SnO2） thin films have been deposited onto pre- heated glass substrates using a spray pyrolysis technique by varying the quantity of spraying solution. The structu...Transparent conducting antimony doped tin oxide （Sb：SnO2） thin films have been deposited onto pre- heated glass substrates using a spray pyrolysis technique by varying the quantity of spraying solution. The structural, morphological, X-ray photoelectron spectroscopy, optical, photoluminescence and electrical properties of these films have been studied. It is found that the films are polycrystalline in nature with a tetragonal crystal structure having orientation along the （211） and （112） planes. Polyhedrons like grains appear in the FE-SEM images. The average grain size increases with increasing spraying quantity. The compositional analysis and electronic behaviour of Sb：SnO2 thin films were studied using X-ray photoelectron spectroscopy. The binding energy of Sn3ds/2 for all samples shows the Sn^4＋ bonding state from SnO2. An intensive violet luminescence peak near 395 nm is observed at room temperature due to oxygen vacancies or donor levels formed by Sb^5＋ ions. The film deposited with 20 cc solution shows 70 % transmittance at 550 nm leading to the highest figure of merit （2.11 × 10^-3 Ω^-1）. The resistivity and carrier concentration vary over 1.22 × 10^-3 to 0.89 × 10^-3Ω cm and 5.19 ×10^20 to 8.52 × 10^20 cm^-3, respectively.展开更多
The physical properties and photoelectrochemical characterization of aluminium doped hematite α-Fe2O3, synthesized by spray pyrolysis, have been investigated in regard to solar energy conversion. Stable Al-doped iron...The physical properties and photoelectrochemical characterization of aluminium doped hematite α-Fe2O3, synthesized by spray pyrolysis, have been investigated in regard to solar energy conversion. Stable Al-doped iron （Ⅲ） oxide thin films synthesized by a spray pyrolysis technique reveals an oxygen deficiency, and the oxide exhibits n-type conductivity confirmed by anodic photocurrent generation. The preparative parameters have been optimized to obtain good quality thin films which are uniform and well adherent to the substrate. The deposited iron oxide thin films show the single hematite phase with polycrystalline rhombohedral crystal structure with crystallite size 20-40 nm. Optical analysis enabled to point out the increase in direct band-gap energy from 2.2 to 2.25 eV with doping concentration which is attributed to a blue shift. The dielectric constant and dielectric loss are studied as a function of frequency. To understand the conduction mechanism in the films, AC conductivity is measured. The conduction occurs by small polaron hopping through mixed valences Fe2＋/3＋ with an electron mobility 300 K of 1.08 cma/（V.s）. The oe-Fe203 exhibits long term chemical stability in neutral solution and has been characterized photoelectrochemically to assess its activity as a photoanode for various electrolytes using white light to obtain I- V characteristics. The Al-doped hematite exhibited a higher photocurrent response when compared with undoped films achieving a power conversion efficiency of 2.37% at 10 at% Al：Fe2O3 thin films along with fill factor 0.38 in NaOH electrolyte. The flat band potential Vfb （-0.87 VscE） is determined by extrapolating the linear part to C-2 = 0 and the slope of the Mott-Schottky plot.展开更多
The influence of substrate temperature and nozzle-to-substrate distance（NSD） on the structural,morphological, optical and electrical properties of Sb：SnO_2 thin films prepared by chemical spray pyrolysis has been a...The influence of substrate temperature and nozzle-to-substrate distance（NSD） on the structural,morphological, optical and electrical properties of Sb：SnO_2 thin films prepared by chemical spray pyrolysis has been analyzed.The structural,morphological,optical and electrical properties were characterized by using XRD,SEM, UV-visible spectrophotometry and Hall effect measurement techniques.It was seen that the films are polycrystalline, having a tetragonal crystal structure with strong orientation along the（200） reflection.The pyramidal crystallites formed due to coalescence were observed from SEM images.The values of highest conductivity,optical transmittance and figure of merit of about 1449（Ω·cm）^（-1）,70%and 5.2×10^（-3）□/Ω,respectively,were observed for a typical film deposited using optimal conditions（substrate temperature = 500℃and NSD = 30 cm）.展开更多
Highly transparent and preferential c-axis oriented nanocrystalline undoped and A1 doped zinc oxide （AZO） thin films have been deposited onto amorphous glass substrate by spray pyrolysis. The XRD studies reveal that...Highly transparent and preferential c-axis oriented nanocrystalline undoped and A1 doped zinc oxide （AZO） thin films have been deposited onto amorphous glass substrate by spray pyrolysis. The XRD studies reveal that AZO with a hexagonal （wurtzite） crystal structure having （002） preferred orientation is formed. The atomic force microscope （AFM） shows uniform surface topography. The optical band gap values of undoped and AZO thin films were changed from 3.34 to 3.35 eV. The band gap energy and photoluminescence are found to depend on the Al doping. Thermoelectric power measurement shows film having n-type in nature. Dielectric constant and loss （tan δ） were found to be frequency dependent. Interparticle interactions in the deposited films are studied by complex impendence spectroscopy.展开更多
： Thin films of zinc oxide have been deposited onto glass/FTO substrates at optimized 400 ℃ by using a chemical spray pyrolysis technique. Deposited films are characterized for their structural, morphological optica...： Thin films of zinc oxide have been deposited onto glass/FTO substrates at optimized 400 ℃ by using a chemical spray pyrolysis technique. Deposited films are characterized for their structural, morphological optical and photocatalytic activity by using XRD, an SEM, a UV-vis spectrophotometer, and a PEC single-cell reactor. Films are polycrystalline and have a hexagonal （wurtzite） crystal structure with c-axis （002） orientation growth perpendicular to the substrate surface. The observed direct band gap is about 3.22 eV for typical films prepared at 400 ℃. The photocatalytic activity of starch with a ZnO photocatalyst has been studied by using a novel photoelectrocatalytic process.展开更多
The fourth fundamental circuit element memristor completes the missing link between charge and mag- netic flux. It consists of the function of the resistor as well as memory in nonlinear fashion. The property of the m...The fourth fundamental circuit element memristor completes the missing link between charge and mag- netic flux. It consists of the function of the resistor as well as memory in nonlinear fashion. The property of the memristor depends on the magnitude and direction of applied potential. This unique property makes it the primi- tive building block for many applications such as resistive memories, soft computing, neuromorphic systems and chaotic circuits etc. In this paper we report TiO2-based nanostructured memristor modelling. The present memris- tor model is constructed in MATLAB environment with consideration of the linear drift model of memristor. The result obtained from the linear drift model is well matched with earlier reported results by other research groups.展开更多
p-CdTe thin films were prepared by spray pyrolysis under different ambient conditions and characterized using photoelectrochemical（PEC）,X-ray diffraction（XRD）,scanning electron microscopy,energy-dispersive analysi...p-CdTe thin films were prepared by spray pyrolysis under different ambient conditions and characterized using photoelectrochemical（PEC）,X-ray diffraction（XRD）,scanning electron microscopy,energy-dispersive analysis by X-ray（EDAX）,and optical transmission studies.The different preparative parameters viz solution pH, solution quantity,substrate temperature and solution concentration have been optimized by the PEC technique in order to get good-quality photosensitive material.XRD analysis shows the polycrystalline nature of the film,having cubic structure with strong（111） orientation.Micrographs reveal that grains are uniformly distributed over the surface of the substrate indicating the well-defined growth of polycrystalline CdTe thin film.The EDAX study for the sample deposited at optimized preparative parameters shows the nearly stoichiometric Cd：Te ratio.Optical absorption shows the presence of direct transition with band gap energy of 1.5 eV.Deposited films exhibit the highest photocurrent of 2.3 mA,a photovoltage of 462 mV,a 0.48 fill factor and 3.4%efficiency for the optimized preparative parameters.展开更多
Cu2ZnSnS4 （CZTS） is a main candidate material for solar energy conversion through both photovoltaics and photocatalysis based on environmentally friendly elements and with a direct band gap of 1.5 eV. We report the ...Cu2ZnSnS4 （CZTS） is a main candidate material for solar energy conversion through both photovoltaics and photocatalysis based on environmentally friendly elements and with a direct band gap of 1.5 eV. We report the synthesis of quasi CUEZnSnS4 microparticles with unprecedented narrow size distributions. The structural, morphological and core level analysis has been carried out by XRD, SEM and XPS techniques. These microparticles have shown excellent photocatalytic activity toward degradation ofRhodamine B dye （RhB） and TNT under visible light. The extent of mineralization has been analyzed by COD and TOC values. Photocatalytic water splitting for HE generation has also been reported.展开更多
The C01-xMnxFez04 （0 ≤ x 〈-5 0.5） ferrite system is synthesized by using an auto combustion technique using metal nitrates. The influence of Mn substitution on the structural, electrical, impedance and magnetic pr...The C01-xMnxFez04 （0 ≤ x 〈-5 0.5） ferrite system is synthesized by using an auto combustion technique using metal nitrates. The influence of Mn substitution on the structural, electrical, impedance and magnetic properties of cobalt ferrite is reported. X-ray diffraction patterns of the prepared samples confirm that the Bragg＇s peak belongs to a spinel cubic crystal structure. The lattice constant of cobalt ferrite increases with the increase in Mn content. The microstructural study is carried out by using the SEM technique and the average grain size continues to increase with increasing manganese content. AC conductivity analysis suggests that the conduction is due to small polaron hopping. DC electrical resistivity decreases with increasing temperature for a Col-xMnxFe204 system showing semiconducting behavior. The activation energy is found to be higher in the paramagnetic region than the ferromagnetic region. Curie temperature decreases with Mn substitution in the host ferrite system. Dielectric dispersion having Maxwell-Wagner-type interfacial polarization has been observed for cobalt ferrite samples. Magnetic properties have been studied by measuring M-H plots. The saturation and remanent magnetization increases with Mn substitution.展开更多
The highly ordered monolayer of submicron size silica （SiO2） particles （235 nm） is developed on p-silicon by using three-step spin-coating in colloidal suspension, which has significant potential in various applic...The highly ordered monolayer of submicron size silica （SiO2） particles （235 nm） is developed on p-silicon by using three-step spin-coating in colloidal suspension, which has significant potential in various applications. The influence of three-step spin speeds, spinning time, acceleration time between different steps, concentration of SiO2 particles in the solution, solution quantity, and the ambient humidity （relative humidity） on the properties ofmonolayer SiO2 are studied in order to achieve a large area monolayer film. A relatively high surface coverage and uniform monolayer film of SiO2 particles in the range of 85%-90% are achieved by appropriate control of the preparative parameters. We conclude that this method can be useful in industrial applications, because of the fabrication speed, surface coverage and cost of the process.展开更多
We developed a simple and inexpensive synthesis of a large-scale close-packed monolayer of polystyrene sphere arrays, which have a variety of applications. The influence of three step spin speeds, spinning time, solut...We developed a simple and inexpensive synthesis of a large-scale close-packed monolayer of polystyrene sphere arrays, which have a variety of applications. The influence of three step spin speeds, spinning time, solution quantity and relative humidity is studied in order to achieve a large area close-packed monolayer. A relatively high surface coverage and uniform monolayer of PS spheres in the range of 85%-90% are achieved by appropriate control of the preparative parameters. Also the effect of the oxygen plasma etching process on the reduction of PS spheres has been studied. We conclude that it can be useful in industrial applications, because of the fabrication speed, surface coverage, control over PS spheres and cost of the process.展开更多
基金Project supported by the Defense Research and Development Organization(DRDO),New Delhi,India(No.ERIP/ER/0503504/M/01/1007)
文摘The photocatalytic decomposition of an eco-persistent AO7 dye with sunlight in an oxygenated aque- ous suspension has been studied under a nano-crystalline hexagonal ZnO photocatalyst. The effect of substrate temperature on the structural, morphological and photoactive properties has been investigated. The degradation of the AO7 dye is achieved using a photoelectrochemical reactor module equipped with ZnO synthesized electrodes. Kinetic parameters have been investigated in terms of a first order rate equation. The rate constant for this hetero- geneous photocatalysis was evaluated as a function of the initial concentration of original species. A substantial reduction in AO7 dye is achieved as analyzed from COD and TOC studies. The mechanism for the degradation could be explained on the basis of the Langmuir-Hinshelwood mechanism.
文摘Transparent conducting antimony doped tin oxide （Sb：SnO2） thin films have been deposited onto pre- heated glass substrates using a spray pyrolysis technique by varying the quantity of spraying solution. The structural, morphological, X-ray photoelectron spectroscopy, optical, photoluminescence and electrical properties of these films have been studied. It is found that the films are polycrystalline in nature with a tetragonal crystal structure having orientation along the （211） and （112） planes. Polyhedrons like grains appear in the FE-SEM images. The average grain size increases with increasing spraying quantity. The compositional analysis and electronic behaviour of Sb：SnO2 thin films were studied using X-ray photoelectron spectroscopy. The binding energy of Sn3ds/2 for all samples shows the Sn^4＋ bonding state from SnO2. An intensive violet luminescence peak near 395 nm is observed at room temperature due to oxygen vacancies or donor levels formed by Sb^5＋ ions. The film deposited with 20 cc solution shows 70 % transmittance at 550 nm leading to the highest figure of merit （2.11 × 10^-3 Ω^-1）. The resistivity and carrier concentration vary over 1.22 × 10^-3 to 0.89 × 10^-3Ω cm and 5.19 ×10^20 to 8.52 × 10^20 cm^-3, respectively.
基金the University Grants Commission,New Delhi,through the UGC-DRSⅡ~(nd) phase Programme(2004-2009)the Defense Research and Development Organization(DRDO)New Delhi,through its project ERIP/ER/0503504/M/01/007 for financial support
文摘The physical properties and photoelectrochemical characterization of aluminium doped hematite α-Fe2O3, synthesized by spray pyrolysis, have been investigated in regard to solar energy conversion. Stable Al-doped iron （Ⅲ） oxide thin films synthesized by a spray pyrolysis technique reveals an oxygen deficiency, and the oxide exhibits n-type conductivity confirmed by anodic photocurrent generation. The preparative parameters have been optimized to obtain good quality thin films which are uniform and well adherent to the substrate. The deposited iron oxide thin films show the single hematite phase with polycrystalline rhombohedral crystal structure with crystallite size 20-40 nm. Optical analysis enabled to point out the increase in direct band-gap energy from 2.2 to 2.25 eV with doping concentration which is attributed to a blue shift. The dielectric constant and dielectric loss are studied as a function of frequency. To understand the conduction mechanism in the films, AC conductivity is measured. The conduction occurs by small polaron hopping through mixed valences Fe2＋/3＋ with an electron mobility 300 K of 1.08 cma/（V.s）. The oe-Fe203 exhibits long term chemical stability in neutral solution and has been characterized photoelectrochemically to assess its activity as a photoanode for various electrolytes using white light to obtain I- V characteristics. The Al-doped hematite exhibited a higher photocurrent response when compared with undoped films achieving a power conversion efficiency of 2.37% at 10 at% Al：Fe2O3 thin films along with fill factor 0.38 in NaOH electrolyte. The flat band potential Vfb （-0.87 VscE） is determined by extrapolating the linear part to C-2 = 0 and the slope of the Mott-Schottky plot.
文摘The influence of substrate temperature and nozzle-to-substrate distance（NSD） on the structural,morphological, optical and electrical properties of Sb：SnO_2 thin films prepared by chemical spray pyrolysis has been analyzed.The structural,morphological,optical and electrical properties were characterized by using XRD,SEM, UV-visible spectrophotometry and Hall effect measurement techniques.It was seen that the films are polycrystalline, having a tetragonal crystal structure with strong orientation along the（200） reflection.The pyramidal crystallites formed due to coalescence were observed from SEM images.The values of highest conductivity,optical transmittance and figure of merit of about 1449（Ω·cm）^（-1）,70%and 5.2×10^（-3）□/Ω,respectively,were observed for a typical film deposited using optimal conditions（substrate temperature = 500℃and NSD = 30 cm）.
基金University Grants Commission, New Delhi for the financial support through the UGC Major Research Project No.39-466/2010(SR)the support from UGC-DRS-I, DST-FIST schemes of Department of Physics
文摘Highly transparent and preferential c-axis oriented nanocrystalline undoped and A1 doped zinc oxide （AZO） thin films have been deposited onto amorphous glass substrate by spray pyrolysis. The XRD studies reveal that AZO with a hexagonal （wurtzite） crystal structure having （002） preferred orientation is formed. The atomic force microscope （AFM） shows uniform surface topography. The optical band gap values of undoped and AZO thin films were changed from 3.34 to 3.35 eV. The band gap energy and photoluminescence are found to depend on the Al doping. Thermoelectric power measurement shows film having n-type in nature. Dielectric constant and loss （tan δ） were found to be frequency dependent. Interparticle interactions in the deposited films are studied by complex impendence spectroscopy.
文摘： Thin films of zinc oxide have been deposited onto glass/FTO substrates at optimized 400 ℃ by using a chemical spray pyrolysis technique. Deposited films are characterized for their structural, morphological optical and photocatalytic activity by using XRD, an SEM, a UV-vis spectrophotometer, and a PEC single-cell reactor. Films are polycrystalline and have a hexagonal （wurtzite） crystal structure with c-axis （002） orientation growth perpendicular to the substrate surface. The observed direct band gap is about 3.22 eV for typical films prepared at 400 ℃. The photocatalytic activity of starch with a ZnO photocatalyst has been studied by using a novel photoelectrocatalytic process.
文摘The fourth fundamental circuit element memristor completes the missing link between charge and mag- netic flux. It consists of the function of the resistor as well as memory in nonlinear fashion. The property of the memristor depends on the magnitude and direction of applied potential. This unique property makes it the primi- tive building block for many applications such as resistive memories, soft computing, neuromorphic systems and chaotic circuits etc. In this paper we report TiO2-based nanostructured memristor modelling. The present memris- tor model is constructed in MATLAB environment with consideration of the linear drift model of memristor. The result obtained from the linear drift model is well matched with earlier reported results by other research groups.
基金financial support through project No. ERIP/ER/0503504/M/01/007
文摘p-CdTe thin films were prepared by spray pyrolysis under different ambient conditions and characterized using photoelectrochemical（PEC）,X-ray diffraction（XRD）,scanning electron microscopy,energy-dispersive analysis by X-ray（EDAX）,and optical transmission studies.The different preparative parameters viz solution pH, solution quantity,substrate temperature and solution concentration have been optimized by the PEC technique in order to get good-quality photosensitive material.XRD analysis shows the polycrystalline nature of the film,having cubic structure with strong（111） orientation.Micrographs reveal that grains are uniformly distributed over the surface of the substrate indicating the well-defined growth of polycrystalline CdTe thin film.The EDAX study for the sample deposited at optimized preparative parameters shows the nearly stoichiometric Cd：Te ratio.Optical absorption shows the presence of direct transition with band gap energy of 1.5 eV.Deposited films exhibit the highest photocurrent of 2.3 mA,a photovoltage of 462 mV,a 0.48 fill factor and 3.4%efficiency for the optimized preparative parameters.
文摘Cu2ZnSnS4 （CZTS） is a main candidate material for solar energy conversion through both photovoltaics and photocatalysis based on environmentally friendly elements and with a direct band gap of 1.5 eV. We report the synthesis of quasi CUEZnSnS4 microparticles with unprecedented narrow size distributions. The structural, morphological and core level analysis has been carried out by XRD, SEM and XPS techniques. These microparticles have shown excellent photocatalytic activity toward degradation ofRhodamine B dye （RhB） and TNT under visible light. The extent of mineralization has been analyzed by COD and TOC values. Photocatalytic water splitting for HE generation has also been reported.
基金the UGC-DSA-I, DSTPURSE and DST-FIST-II programs for financial support
文摘The C01-xMnxFez04 （0 ≤ x 〈-5 0.5） ferrite system is synthesized by using an auto combustion technique using metal nitrates. The influence of Mn substitution on the structural, electrical, impedance and magnetic properties of cobalt ferrite is reported. X-ray diffraction patterns of the prepared samples confirm that the Bragg＇s peak belongs to a spinel cubic crystal structure. The lattice constant of cobalt ferrite increases with the increase in Mn content. The microstructural study is carried out by using the SEM technique and the average grain size continues to increase with increasing manganese content. AC conductivity analysis suggests that the conduction is due to small polaron hopping. DC electrical resistivity decreases with increasing temperature for a Col-xMnxFe204 system showing semiconducting behavior. The activation energy is found to be higher in the paramagnetic region than the ferromagnetic region. Curie temperature decreases with Mn substitution in the host ferrite system. Dielectric dispersion having Maxwell-Wagner-type interfacial polarization has been observed for cobalt ferrite samples. Magnetic properties have been studied by measuring M-H plots. The saturation and remanent magnetization increases with Mn substitution.
文摘The highly ordered monolayer of submicron size silica （SiO2） particles （235 nm） is developed on p-silicon by using three-step spin-coating in colloidal suspension, which has significant potential in various applications. The influence of three-step spin speeds, spinning time, acceleration time between different steps, concentration of SiO2 particles in the solution, solution quantity, and the ambient humidity （relative humidity） on the properties ofmonolayer SiO2 are studied in order to achieve a large area monolayer film. A relatively high surface coverage and uniform monolayer film of SiO2 particles in the range of 85%-90% are achieved by appropriate control of the preparative parameters. We conclude that this method can be useful in industrial applications, because of the fabrication speed, surface coverage and cost of the process.
文摘We developed a simple and inexpensive synthesis of a large-scale close-packed monolayer of polystyrene sphere arrays, which have a variety of applications. The influence of three step spin speeds, spinning time, solution quantity and relative humidity is studied in order to achieve a large area close-packed monolayer. A relatively high surface coverage and uniform monolayer of PS spheres in the range of 85%-90% are achieved by appropriate control of the preparative parameters. Also the effect of the oxygen plasma etching process on the reduction of PS spheres has been studied. We conclude that it can be useful in industrial applications, because of the fabrication speed, surface coverage, control over PS spheres and cost of the process.
