L.P. Purohit - Academia.edu (original) (raw)

Papers by L.P. Purohit

Research paper thumbnail of Exploring the Nonlinear Optical Limiting Activity of Para-Aminobenzoic Acid by Experimental and Dft Approach

Research paper thumbnail of rGO-ZnO nanocomposites as efficient photocatalyst for degradation of 4-BP and DEP using high temperature refluxing method in in-situ condition

Journal of Hazardous Materials, 2021

rGO-ZnO nanocomposites as efficient photocatalyst for degradation of 4-BP and DEP using high temp... more rGO-ZnO nanocomposites as efficient photocatalyst for degradation of 4-BP and DEP using high temperature refluxing method in in-situ condition,

Research paper thumbnail of Structural & Optical Characterization of Gex Se80-x Pb20 Thin Films Prepared by Thermal Evaporation Technique

Abstract- Vacuum evaporated films of GexSe80-xPb20 have been characterized by using optical spect... more Abstract- Vacuum evaporated films of GexSe80-xPb20 have been characterized by using optical spectroscopy (especially transmission and absorption spectra). The chalcogenide glass of GexSe80-xPb20 has been prepared by melt quenching technique. Thin films of GexSe80-xPb20 are deposited by vacuum thermal evaporation technique on highly clean glass substrates and their optical properties such as refractive index (n), extinction coefficient (k), and energy band gap have been studied. The transmission spectra in the spectral range 300-2000 nm has been used to calculate the refractive index (n), extinction coefficient (k) of the films have been studied. Optical spectroscopy of the films has been done with the help of the Shimadzu U-3600 (UV-Vis-NIR) Spectrophotometer. The structural analysis is studied through X-ray diffraction.

Research paper thumbnail of EFFECT OF METHODS OF HARVESTING, GRADING AND CHEMICAL TREATMENTS ON THE ESTIMATES OF POST HARVEST LOSSES IN RAJAPURI MANGO (Mangifera indica L.)

Research paper thumbnail of Structural & Optical Characterization of Gex Se80-x Pb20 Thin Films Prepared by Thermal Evaporation Technique

Vacuum evaporated films of GexSe80-xPb20 have been characterized by using optical spectroscopy (e... more Vacuum evaporated films of GexSe80-xPb20 have been characterized by using optical spectroscopy (especially transmission and absorption spectra). The chalcogenide glass of GexSe80-xPb20 has been prepared by melt quenching technique. Thin films of GexSe80-xPb20 are deposited by vacuum thermal evaporation technique on highly clean glass substrates and their optical properties such as refractive index (n), extinction coefficient (k), and energy band gap have been studied. The transmission spectra in the spectral range 300-2000 nm has been used to calculate the refractive index (n), extinction coefficient (k) of the films have been studied. Optical spectroscopy of the films has been done with the help of the Shimadzu U-3600 (UVVis-NIR) Spectrophotometer. The structural analysis is studied through X-ray diffraction.

Research paper thumbnail of Fm STRUCTURAL INVESTIGATION OF SBGESE GLASSES BY HIGH RESOLUTION X-RAY PHOTOELECTRON SPECTROSCOPY

The evolution of the structure of Sb8Ge32Se60 (Z 2.72) and Sb20Ge20Se60 (Z 2.60) chalcogenide gla... more The evolution of the structure of Sb8Ge32Se60 (Z 2.72) and Sb20Ge20Se60 (Z 2.60) chalcogenide glasses is determined by high resolution X-ray photoelectron spectroscopy. Glasses with Z 2.60 the structure consists of deformed tetrahedra and pyramids, in which at least one Se atom is substituted by Ge or Sb atom. For the Z 2.72 structure consisting of shared pyramids and tetrahedra with two or more Se atoms substituted by the cations. At the same time, Se-Se dimers are present in both compositions.

Research paper thumbnail of Effect of doping concentration on the conductivity and optical properties of p-type ZnO thin films

Physica B: Condensed Matter, 2016

ABSTRACT

Research paper thumbnail of Spin coating of ZnS nanostructures on filter paper and their characterization

Physica E: Low-dimensional Systems and Nanostructures, 2016

In this paper we have reported spin coating of Cu doped Zinc sulphide nanostructures on filter pa... more In this paper we have reported spin coating of Cu doped Zinc sulphide nanostructures on filter paper flexible substrates. Zinc chloride and thiourea were used as a precursors of zinc and sulphur. The samples were characterized by XRD, FE-SEM, EDX and UV-visible spectrum studies. All the diffractogram peaks confirm the cubic structure of ZnS with small peak of Cu indicates incorporation of Cu into ZnS lattice. FE-SEM micrographs exhibit fibrous morphologies of ZnS structures on filter paper. Compound structures on flexible substrates show ohmic behavior with conductivity about 3.07x10 6 (cm)-1 to 4.27x10 6 (cm)-1. Excellent photoluminescence property doped with copper makes them suitable for flexible opto-electronic devices.

Research paper thumbnail of Substrate dependent structural, optical and electrical properties of ZnS thin films grown by RF sputtering

Physica E: Low-dimensional Systems and Nanostructures, 2016

Zinc sulphide (ZnS) films are of great importance for applications in various optoelectronic devi... more Zinc sulphide (ZnS) films are of great importance for applications in various optoelectronic devices. ZnS thin films were grown on glass, indium tin oxide (ITO) and Corning glass substrates by radio-frequency magnetron sputtering at a temperature of 373 K and a comparative study of the structural, optical and electrical properties was performed using X-ray diffraction (XRD), scanning electron microscopy, optical and current-voltage (I-V) measurements. The XRD patterns showed that the sputtered thin films exhibited good crystallinity with the (111) peak around 2θ = 28.3˚ indicating preferential orientation of the cubic structure. The maximum strain and most densely packed grains were obtained for the Corning glass substrate. The transmittance spectra of the films were measured in the wavelength range from 200 to 800 nm, showing that the films are about 77% transparent in the visible region. A slight change of 3.50 eV to 3.54 eV was found for the bandgap of the films deposited on different substrates. The ZnS thin films deposited on Corning glass show better crystallinity, morphology and I-V characteristics than that deposited on ordinary glass and ITO substrates.

Research paper thumbnail of Sputtered Al–N codoped p-type transparent ZnO thin films suitable for optoelectronic devices

Optik - International Journal for Light and Electron Optics, 2016

Abstract Aluminum–nitrogen (Al–N) codoped zinc oxide (ZnO) thin films were grown on glass substra... more Abstract Aluminum–nitrogen (Al–N) codoped zinc oxide (ZnO) thin films were grown on glass substrate by radio frequency (RF) reactive magnetron sputtering using aluminum doped zinc oxide (AZO, 2.5 wt% Al 2 O 3 ) target and N 2 as reactive gas. The structural, morphology, optical and electrical properties were also investigated with different flow rate of N 2 gas. X-ray diffraction results shows that codoped ZnO thin films have similar wurtzite structure like undoped ZnO film. Al–N thin films have high transparency 78% in visible region as the nitrogen flow rate increases the transparency and band gap decreases. The best p-type codoped sample shows a resistivity and hole concentration of 0.554 Ω cm and 8.3 × 10 19 cm −3 at room temperature, respectively. Current–voltage ( I – V ) characteristics of p-type codoped ZnO thin films are also discussed.

Research paper thumbnail of Photocatalytic properties of Mn-doped NiO spherical nanoparticles synthesized from sol-gel method

Optik, 2016

Abstract Mn-doped NiO (NiO:Mn) nanopowders were synthesized from an inexpensive sol-gel method. T... more Abstract Mn-doped NiO (NiO:Mn) nanopowders were synthesized from an inexpensive sol-gel method. The XRD peak profile analysis of NiO:Mn nanopowders confirmed the cubic structure. The spherical nanoparticles of NiO:Mn were evaluated from the SEM and TEM analysis and the grain size decreased as the Mn concentration increased. The average crystallite size decreased from 35.44 nm to 30.5 nm and the bandgap increased from 3.79 eV to 3.95 eV as the Mn concentration increased from 0 wt.% to 4 wt.%. The photocatalytic properties of NiO:Mn nanopowders were measured for the lowest and highest Mn dopant concentrations (Mn: 0 & 4 wt.%) by using the methylene blue dye under UV illumination. The NiO:Mn (Mn: 4 wt.%) nanoparticles showed the highest photocatalytic activity due to the highest activation sites. Therefore, it is revealed that the Mn: 4 wt.% nanoparticles are observed to be more suitable for the photocatalytic activity of methylene blue dye degradation.

Research paper thumbnail of Comparative Study of Synthesis of CdO-ZnO Nanocomposite Thin Films by Different Methods: A Review

Nanoscience & Technology: Open Access, 2016

II-VI semiconductors, owing to the availability of a large variety of techniques to prepare it, t... more II-VI semiconductors, owing to the availability of a large variety of techniques to prepare it, the large number of structures and nanostructures in which it can be condensed, as well as the large and varied number of industrial applications [13]. ZnO has a wurtzite structure in which the oxygen atoms are arranged in a hexagonal-close-packed lattice with zinc atoms occupying half the tetrahedral sites. This is a very well known semiconductor with a wide band gap in the near ultraviolet of ~ 3.37 eV at room temperature [14]. Cadmium oxide (CdO) is also a well-known II-VI n-type semiconductor that has interesting properties for optoelectronic applications due to its large band gap, low electrical resistivity and high optical transmittance in the visible region of the solar spectrum [15]. It can be found in various types of nano structures with a variety of properties and applications such as UV and visible photoluminescence, photo catalysts and field emission, ambient temperature ferromagnetism and high electronic mobility [16] as well as photo detectors, solar cells, piezoelectric devices [17]. It has been well studied as a sensor material to detect most of the reducing gases [18]. CdO has a rock salt crystal structure with a direct band gap of 2.2 eV to 2.5 eV and indirect band gap of 1.98 eV, which makes it useful for a wide range of applications such as solar cells, photodiodes, and transparent electrodes and sensors [19-22]. These interesting materials have been synthesized by various techniques, including electrode position, molecular beam epitaxy [23], sol-gel [24], thermal decomposition technique [25], pulsed laser deposition [26], spray pyrolysis [27], magnetron sputtering [28] and ultrasonic spray pyrolysis (USP) techniques [29]. In the present work we have done a comparative study of transports properties of ZnO-CdO thin films synthesis by sol-gel, magnetron sputtering and spray pyrolisis techniques. Deposition of thin films Sol-gel Method Sol-gel method is an attractive method to obtain the films of different materials and this is well known for its low cost,

Research paper thumbnail of Numerical Simulation of Magnetron Injection Gun for 1MW 120 GHZ Gyrotron

Progress In Electromagnetics Research Letters, 2010

A 40 A triode-type magnetron injection gun for a 1 MW, 120 GHz gyrotron has been designed. The pr... more A 40 A triode-type magnetron injection gun for a 1 MW, 120 GHz gyrotron has been designed. The preliminary design has been obtained by using some trade-off equations. Computer simulation has been performed by using the commercially available code EGUN and the in-house developed code MIGANS. The operating voltages of the modulating anode and the accelerating anode are 60 kV and 80 kV, respectively. The electron beam with a low transverse velocity spread (δβ ⊥ max = 3.3%) and velocity ratio, α = 1.38 at beam current = 40 A is obtained. The simulated results of the MIG obtained with the EGUN code have been validated with another trajectory code TRAK. The results on the design output parameters obtained by these two codes were found to be in close agreement. The sensitivity study has been carried out by changing the different gun parameters to decide the fabrication tolerance.

Research paper thumbnail of Ternary alloyed CdS1−xSex quantum dots on TiO2/ZnS electrodes for quantum dots-sensitized solar cells

Journal of Alloys and Compounds, 2021

Abstract Ternary alloyed and tunable band CdS1−xSex quantum dots (QDs) were prepared via successi... more Abstract Ternary alloyed and tunable band CdS1−xSex quantum dots (QDs) were prepared via successive ionic layer absorption and reaction (SILAR) method. The as-prepared photoanodes at different concentrations were characterized for structural, surface morphological, optical and electrical analysis. The result indicated that the photoresponse region and energy band of prepared CdS1−xSexQDs could be varied by controlling the ratios of S and Se. An aqueous solution of polysulfide electrolyte acted as redox mediator. The QDs size were varied from 10.14 nm to 3.362 nm confirms the quantum confinement effect. The highest and lowest photo conversion efficiency (η) of TiO2/ZnS/CdS1−xSex/ZnS quantum dots-sensitized solar cells (QDSSCs) using CuS counter electrode was obtained 5.12% and 3.43%, respectively. Developing the ZnS layer between the TiO2/QDs and at the interface of QD/electrolyte helps to suppress the charge recombination rate and provide the potential barrier between QDs and electrolyte.The photoconversion efficiency was evaluated by using a solar simulator under illumination with an AM 1.5 G spectrum having light intensity of 100 mWcm−2. These results are encouraging and reveals that tunable energy band QDs controlled by the ratio of atoms can contribute an effective approach for developing the higher efficiency of QDSSCs.

Research paper thumbnail of Mesoporous ZnO/TiO2 photoanodes for quantum dot sensitized solar cell

Optical Materials, 2021

Abstract In the present work, different photoanodes, namely ZnO/TiO2 and bare TiO2 were deposited... more Abstract In the present work, different photoanodes, namely ZnO/TiO2 and bare TiO2 were deposited on fluorine-doped tin oxide (FTO) conductive glass substrate by the doctor blade method. CdS quantum dot was deposited on the photoanode by using the successive ionic layer adsorption and reaction (SILAR) method. In this, CuS was also coated on the FTO substrate which acts as the counter electrode. The structural, optical and electrical properties of deposited photoanodes and counter electrode were successfully investigated. The J-V characteristic and the other parameters of quantum dot sensitized solar cell (QDSSC) were analyzed by a using solar simulator under the illumination of a xenon short arc lamp an AM 1.5 G spectrum, having the light intensity of 100 mWcm−2. The power conversion efficiency of QDSSC using different photoanodes were compared. Due to the formation of energy barrier, ZnO/TiO2 using CdS QDs have higher efficiency ( 1.73%) as compared to bare TiO2 using CdS QDs ( 1.01%). It was found that ZnO/TiO2 based QDSSC exhibits 71% higher efficiency than that of TiO2 based QDSSC. The incident photon-to-current conversion efficiency (IPCE) obtained for ZnO/TiO2 electrode were approximately 46% (at 465 nm) and for bare TiO2 electrode around 34% (at 446 nm). The overall investigation supports the electron transport and enhanced performance of the ZnO/TiO2/CdS solar cell.

Research paper thumbnail of Hetro-nanostructured Se-ZnO sustained with RGO nanosheets for enhanced photocatalytic degradation of p-Chlorophenol, p-Nitrophenol and Methylene blue

Separation and Purification Technology, 2021

Abstract The persistent organic pollutants predominantly phenolic compounds and organic dyes are ... more Abstract The persistent organic pollutants predominantly phenolic compounds and organic dyes are the hazardous pollutants into the environment, considered as crucial contaminants in aquatic environment as well and cause to different severe detrimental impact on the human being and other living systems. In the present investigation, hetro-nanostructured Se-ZnO incorporated with different weight % of RGO (0, 1, 3, 5 and 8%) coded as SeZG-0, SeZG-1, SeZG-3, SeZG-5 and SeZG-8 nanocomposites were fabricated using a facile and simple refluxing method for the enhanced photocatalytic degradation and complete mineralization of phenolic compounds (p-Chlorophenol, p-Nitrophenol) and organic dye (methylene blue) via advanced oxidation technique. XRD, Raman, FT-IR, SEM and UV–Vis DRS techniques were used to determine the structural, morphological and optical properties of the synthesized nanocomposites comprehensively, respectively. p-chlorophenol, p-nitrophenol and methylene blue were considered as model organic pollutants in water for the assessment of photocatalytic performance of the SeZG nanocomposites and the mineralization efficiency was obtained 99.02, 98.89 and 99.41% under irradiation of UV light for 105 min, 90 min and 35 min, respectively. The outstanding photocatalytic performance of SeZG nanocomposites revealed by the significant obstruction in the recombination of charge carriers owing to the presence of Se and RGO nanosheets resulting production of additional reactive oxygen species and photodegradation of organic contaminants (p-chlorophenol, p-nitrophenol and methylene) from water. Finally, photodegradation mechanism is proposed.

Research paper thumbnail of Wrinkle type nanostructured Y-doped ZnO thin films for oxygen gas sensing at lower operating temperature

Materials Research Bulletin, 2021

Research paper thumbnail of ZnO-CdO Nanocomposites Incorporated With Graphene Oxide Nanosheets for Efficient Photocatalytic Degradation of Bisphenol A, Thymol Blue and Ciprofloxacin

Journal of Hazardous Materials, 2021

The widespread existence of different organic contaminants mostly phenolic compounds, organic dye... more The widespread existence of different organic contaminants mostly phenolic compounds, organic dyes and antibiotics in water bodies initiated by the various industrial wastes that raised great scientific concern and public awareness as well recently owing to their prospective capability to spread these contaminants resistant gene and pose hazard to human. In the present study, a series of nanostructured ZnO-CdO incorporated with reduced graphene oxide (ZCG nanocomposites) were successfully synthesized by a simple refluxing method and characterized by using the X-ray diffraction (XRD), Raman spectroscopy, FT-IR spectroscopy, photoluminescence spectroscopy, field emission-scanning microscope (FE-SEM) and UV-visible diffused reflectance spectroscopy (DRS) for the photocatalytic degradation of bisphenol A (BPA), thymol blue (ThB) and ciprofloxacin (CFn) with illumination of UV light. The maximum degradation and mineralization of BPA, ThB and CFn was achieved around 98.5%, 98.38% and 99.28% over the ZCG-5 nanocomposite photocatalyst after UV light irradiation for 180 min, 120 min and 75 min, respectively. The superior photocatalytic activity of ZCG-5 ascribed to enhance adsorption capacity, effective separation of charge carriers consequential for the production of more ROS after incorporation of RGO nanosheets with ZnO-CdO in photocatalyst. The conceivable photocatalytic degradation mechanism of BPA, ThB and CFn was elucidated through ROS identification and the assessment of photocatalyst stability by reusability, EEO (kwh/m3order) and UV light dose (mJ/cm2) were evaluated. The plausible photocatalytic degradation pathways were proposed for the degradation of BPA, ThB and CFn via GC-MS analysis. The present work investigates the efficient removal of BPA, ThB and CFn using ZCG nanocomposites as photocatalyst.

Research paper thumbnail of Chalcogen-doped zinc oxide nanoparticles for photocatalytic degradation of Rhodamine B under the irradiation of ultraviolet light

Materials Today Chemistry, 2021

Abstract In the present work, the chalcogen (Se2+)-doped ZnO nanoparticles (SeZO-NPs) were synthe... more Abstract In the present work, the chalcogen (Se2+)-doped ZnO nanoparticles (SeZO-NPs) were synthesized using sol-gel precipitation method and tested for photocatalytic degradation of Rhodamine B (RhB). X-ray diffraction pattern of SeZO-NPs showed the hexagonal wurtzite crystal structure regardless of Se concentration. The band edge and defect-level emissions of SeZO-NPs were determined by using the photoluminescence spectra with the excitation source of 370 nm. The bandgap, Eg, of SeZO-NPs was measured from diffused reflectance spectroscopy, which increased from 3.22 to 3.26 eV as Se concentration increased from 0 to 10 wt.%. The highest specific surface area and lowest pore size of 5-SeZO-NPs were observed to be 36.42 m2/g and 13.48 nm, respectively. The photocatalytic degradation of SeZO-NPs was measured under the illumination of ultraviolet (UV) light. The double donor (Se) played an important role toward photodegradation of RhB via reducing the recombination of charge carriers. The highest photocatalytic degradation (98.23%) and mineralization were achieved for the sample 5-SeZO (Se: 5 wt.%). The improved photocatalytic performance of 5-SeZO was attributed to the optimum Se dopant concentration for the production of more reactive oxygen species because of effective separation of charge carriers in UV light.

Research paper thumbnail of Improved stability of gas sensor by inclusion of Sb in nanostructured SnO2 thin films grown on sodalime

Journal of Alloys and Compounds, 2020

Abstract In the present work an attempt has been made to improve the stability in the oxygen gas ... more Abstract In the present work an attempt has been made to improve the stability in the oxygen gas sensing property of SnO2 with Sb doping using low cost sol-gel spin coating techniques. Un-doped and Sb (0, 0.5, 1.0, 1.5 and 2 at. %) doped SnO2 thin films were deposited on sodalime glass substrate by spin coating technique at 2500 rpm and annealed at 400 °C. The properties of thin films were investigated by their structural, morphological, optical and electrical analysis for oxygen gas sensing at low operating temperature. The crystalline phase and crystallite size were measured by X-ray diffraction pattern. It was observed that peaks show the polycrystalline nature with the tetragonal crystal structure. Scanning electron microscopic images revealed that all thin films have spherical type morphology. The transmittance spectra were recorded in the wavelength range 200–800 nm and optical band gap was varied from 3.56 eV to 3.92 eV with increasing doping concertation. The I–V measurements were recorded from −5 V to 5 V by two probe method. The highest conductivity was observed for 1 at. % Sb doped SnO2 thin film sample. The gas sensing properties of above thin films were measured as a function of operating temperature in the temperature range from 30 °C to 125 °C and the highest response was obtained for 1 at. % Sb doped SnO2 thin film sample. It has been observed from the experimental results that Sb doped SnO2 thin films exhibit the improved gas response, low operating temperature and good selectivity.

Research paper thumbnail of Exploring the Nonlinear Optical Limiting Activity of Para-Aminobenzoic Acid by Experimental and Dft Approach

Research paper thumbnail of rGO-ZnO nanocomposites as efficient photocatalyst for degradation of 4-BP and DEP using high temperature refluxing method in in-situ condition

Journal of Hazardous Materials, 2021

rGO-ZnO nanocomposites as efficient photocatalyst for degradation of 4-BP and DEP using high temp... more rGO-ZnO nanocomposites as efficient photocatalyst for degradation of 4-BP and DEP using high temperature refluxing method in in-situ condition,

Research paper thumbnail of Structural & Optical Characterization of Gex Se80-x Pb20 Thin Films Prepared by Thermal Evaporation Technique

Abstract- Vacuum evaporated films of GexSe80-xPb20 have been characterized by using optical spect... more Abstract- Vacuum evaporated films of GexSe80-xPb20 have been characterized by using optical spectroscopy (especially transmission and absorption spectra). The chalcogenide glass of GexSe80-xPb20 has been prepared by melt quenching technique. Thin films of GexSe80-xPb20 are deposited by vacuum thermal evaporation technique on highly clean glass substrates and their optical properties such as refractive index (n), extinction coefficient (k), and energy band gap have been studied. The transmission spectra in the spectral range 300-2000 nm has been used to calculate the refractive index (n), extinction coefficient (k) of the films have been studied. Optical spectroscopy of the films has been done with the help of the Shimadzu U-3600 (UV-Vis-NIR) Spectrophotometer. The structural analysis is studied through X-ray diffraction.

Research paper thumbnail of EFFECT OF METHODS OF HARVESTING, GRADING AND CHEMICAL TREATMENTS ON THE ESTIMATES OF POST HARVEST LOSSES IN RAJAPURI MANGO (Mangifera indica L.)

Research paper thumbnail of Structural & Optical Characterization of Gex Se80-x Pb20 Thin Films Prepared by Thermal Evaporation Technique

Vacuum evaporated films of GexSe80-xPb20 have been characterized by using optical spectroscopy (e... more Vacuum evaporated films of GexSe80-xPb20 have been characterized by using optical spectroscopy (especially transmission and absorption spectra). The chalcogenide glass of GexSe80-xPb20 has been prepared by melt quenching technique. Thin films of GexSe80-xPb20 are deposited by vacuum thermal evaporation technique on highly clean glass substrates and their optical properties such as refractive index (n), extinction coefficient (k), and energy band gap have been studied. The transmission spectra in the spectral range 300-2000 nm has been used to calculate the refractive index (n), extinction coefficient (k) of the films have been studied. Optical spectroscopy of the films has been done with the help of the Shimadzu U-3600 (UVVis-NIR) Spectrophotometer. The structural analysis is studied through X-ray diffraction.

Research paper thumbnail of Fm STRUCTURAL INVESTIGATION OF SBGESE GLASSES BY HIGH RESOLUTION X-RAY PHOTOELECTRON SPECTROSCOPY

The evolution of the structure of Sb8Ge32Se60 (Z 2.72) and Sb20Ge20Se60 (Z 2.60) chalcogenide gla... more The evolution of the structure of Sb8Ge32Se60 (Z 2.72) and Sb20Ge20Se60 (Z 2.60) chalcogenide glasses is determined by high resolution X-ray photoelectron spectroscopy. Glasses with Z 2.60 the structure consists of deformed tetrahedra and pyramids, in which at least one Se atom is substituted by Ge or Sb atom. For the Z 2.72 structure consisting of shared pyramids and tetrahedra with two or more Se atoms substituted by the cations. At the same time, Se-Se dimers are present in both compositions.

Research paper thumbnail of Effect of doping concentration on the conductivity and optical properties of p-type ZnO thin films

Physica B: Condensed Matter, 2016

ABSTRACT

Research paper thumbnail of Spin coating of ZnS nanostructures on filter paper and their characterization

Physica E: Low-dimensional Systems and Nanostructures, 2016

In this paper we have reported spin coating of Cu doped Zinc sulphide nanostructures on filter pa... more In this paper we have reported spin coating of Cu doped Zinc sulphide nanostructures on filter paper flexible substrates. Zinc chloride and thiourea were used as a precursors of zinc and sulphur. The samples were characterized by XRD, FE-SEM, EDX and UV-visible spectrum studies. All the diffractogram peaks confirm the cubic structure of ZnS with small peak of Cu indicates incorporation of Cu into ZnS lattice. FE-SEM micrographs exhibit fibrous morphologies of ZnS structures on filter paper. Compound structures on flexible substrates show ohmic behavior with conductivity about 3.07x10 6 (cm)-1 to 4.27x10 6 (cm)-1. Excellent photoluminescence property doped with copper makes them suitable for flexible opto-electronic devices.

Research paper thumbnail of Substrate dependent structural, optical and electrical properties of ZnS thin films grown by RF sputtering

Physica E: Low-dimensional Systems and Nanostructures, 2016

Zinc sulphide (ZnS) films are of great importance for applications in various optoelectronic devi... more Zinc sulphide (ZnS) films are of great importance for applications in various optoelectronic devices. ZnS thin films were grown on glass, indium tin oxide (ITO) and Corning glass substrates by radio-frequency magnetron sputtering at a temperature of 373 K and a comparative study of the structural, optical and electrical properties was performed using X-ray diffraction (XRD), scanning electron microscopy, optical and current-voltage (I-V) measurements. The XRD patterns showed that the sputtered thin films exhibited good crystallinity with the (111) peak around 2θ = 28.3˚ indicating preferential orientation of the cubic structure. The maximum strain and most densely packed grains were obtained for the Corning glass substrate. The transmittance spectra of the films were measured in the wavelength range from 200 to 800 nm, showing that the films are about 77% transparent in the visible region. A slight change of 3.50 eV to 3.54 eV was found for the bandgap of the films deposited on different substrates. The ZnS thin films deposited on Corning glass show better crystallinity, morphology and I-V characteristics than that deposited on ordinary glass and ITO substrates.

Research paper thumbnail of Sputtered Al–N codoped p-type transparent ZnO thin films suitable for optoelectronic devices

Optik - International Journal for Light and Electron Optics, 2016

Abstract Aluminum–nitrogen (Al–N) codoped zinc oxide (ZnO) thin films were grown on glass substra... more Abstract Aluminum–nitrogen (Al–N) codoped zinc oxide (ZnO) thin films were grown on glass substrate by radio frequency (RF) reactive magnetron sputtering using aluminum doped zinc oxide (AZO, 2.5 wt% Al 2 O 3 ) target and N 2 as reactive gas. The structural, morphology, optical and electrical properties were also investigated with different flow rate of N 2 gas. X-ray diffraction results shows that codoped ZnO thin films have similar wurtzite structure like undoped ZnO film. Al–N thin films have high transparency 78% in visible region as the nitrogen flow rate increases the transparency and band gap decreases. The best p-type codoped sample shows a resistivity and hole concentration of 0.554 Ω cm and 8.3 × 10 19 cm −3 at room temperature, respectively. Current–voltage ( I – V ) characteristics of p-type codoped ZnO thin films are also discussed.

Research paper thumbnail of Photocatalytic properties of Mn-doped NiO spherical nanoparticles synthesized from sol-gel method

Optik, 2016

Abstract Mn-doped NiO (NiO:Mn) nanopowders were synthesized from an inexpensive sol-gel method. T... more Abstract Mn-doped NiO (NiO:Mn) nanopowders were synthesized from an inexpensive sol-gel method. The XRD peak profile analysis of NiO:Mn nanopowders confirmed the cubic structure. The spherical nanoparticles of NiO:Mn were evaluated from the SEM and TEM analysis and the grain size decreased as the Mn concentration increased. The average crystallite size decreased from 35.44 nm to 30.5 nm and the bandgap increased from 3.79 eV to 3.95 eV as the Mn concentration increased from 0 wt.% to 4 wt.%. The photocatalytic properties of NiO:Mn nanopowders were measured for the lowest and highest Mn dopant concentrations (Mn: 0 & 4 wt.%) by using the methylene blue dye under UV illumination. The NiO:Mn (Mn: 4 wt.%) nanoparticles showed the highest photocatalytic activity due to the highest activation sites. Therefore, it is revealed that the Mn: 4 wt.% nanoparticles are observed to be more suitable for the photocatalytic activity of methylene blue dye degradation.

Research paper thumbnail of Comparative Study of Synthesis of CdO-ZnO Nanocomposite Thin Films by Different Methods: A Review

Nanoscience & Technology: Open Access, 2016

II-VI semiconductors, owing to the availability of a large variety of techniques to prepare it, t... more II-VI semiconductors, owing to the availability of a large variety of techniques to prepare it, the large number of structures and nanostructures in which it can be condensed, as well as the large and varied number of industrial applications [13]. ZnO has a wurtzite structure in which the oxygen atoms are arranged in a hexagonal-close-packed lattice with zinc atoms occupying half the tetrahedral sites. This is a very well known semiconductor with a wide band gap in the near ultraviolet of ~ 3.37 eV at room temperature [14]. Cadmium oxide (CdO) is also a well-known II-VI n-type semiconductor that has interesting properties for optoelectronic applications due to its large band gap, low electrical resistivity and high optical transmittance in the visible region of the solar spectrum [15]. It can be found in various types of nano structures with a variety of properties and applications such as UV and visible photoluminescence, photo catalysts and field emission, ambient temperature ferromagnetism and high electronic mobility [16] as well as photo detectors, solar cells, piezoelectric devices [17]. It has been well studied as a sensor material to detect most of the reducing gases [18]. CdO has a rock salt crystal structure with a direct band gap of 2.2 eV to 2.5 eV and indirect band gap of 1.98 eV, which makes it useful for a wide range of applications such as solar cells, photodiodes, and transparent electrodes and sensors [19-22]. These interesting materials have been synthesized by various techniques, including electrode position, molecular beam epitaxy [23], sol-gel [24], thermal decomposition technique [25], pulsed laser deposition [26], spray pyrolysis [27], magnetron sputtering [28] and ultrasonic spray pyrolysis (USP) techniques [29]. In the present work we have done a comparative study of transports properties of ZnO-CdO thin films synthesis by sol-gel, magnetron sputtering and spray pyrolisis techniques. Deposition of thin films Sol-gel Method Sol-gel method is an attractive method to obtain the films of different materials and this is well known for its low cost,

Research paper thumbnail of Numerical Simulation of Magnetron Injection Gun for 1MW 120 GHZ Gyrotron

Progress In Electromagnetics Research Letters, 2010

A 40 A triode-type magnetron injection gun for a 1 MW, 120 GHz gyrotron has been designed. The pr... more A 40 A triode-type magnetron injection gun for a 1 MW, 120 GHz gyrotron has been designed. The preliminary design has been obtained by using some trade-off equations. Computer simulation has been performed by using the commercially available code EGUN and the in-house developed code MIGANS. The operating voltages of the modulating anode and the accelerating anode are 60 kV and 80 kV, respectively. The electron beam with a low transverse velocity spread (δβ ⊥ max = 3.3%) and velocity ratio, α = 1.38 at beam current = 40 A is obtained. The simulated results of the MIG obtained with the EGUN code have been validated with another trajectory code TRAK. The results on the design output parameters obtained by these two codes were found to be in close agreement. The sensitivity study has been carried out by changing the different gun parameters to decide the fabrication tolerance.

Research paper thumbnail of Ternary alloyed CdS1−xSex quantum dots on TiO2/ZnS electrodes for quantum dots-sensitized solar cells

Journal of Alloys and Compounds, 2021

Abstract Ternary alloyed and tunable band CdS1−xSex quantum dots (QDs) were prepared via successi... more Abstract Ternary alloyed and tunable band CdS1−xSex quantum dots (QDs) were prepared via successive ionic layer absorption and reaction (SILAR) method. The as-prepared photoanodes at different concentrations were characterized for structural, surface morphological, optical and electrical analysis. The result indicated that the photoresponse region and energy band of prepared CdS1−xSexQDs could be varied by controlling the ratios of S and Se. An aqueous solution of polysulfide electrolyte acted as redox mediator. The QDs size were varied from 10.14 nm to 3.362 nm confirms the quantum confinement effect. The highest and lowest photo conversion efficiency (η) of TiO2/ZnS/CdS1−xSex/ZnS quantum dots-sensitized solar cells (QDSSCs) using CuS counter electrode was obtained 5.12% and 3.43%, respectively. Developing the ZnS layer between the TiO2/QDs and at the interface of QD/electrolyte helps to suppress the charge recombination rate and provide the potential barrier between QDs and electrolyte.The photoconversion efficiency was evaluated by using a solar simulator under illumination with an AM 1.5 G spectrum having light intensity of 100 mWcm−2. These results are encouraging and reveals that tunable energy band QDs controlled by the ratio of atoms can contribute an effective approach for developing the higher efficiency of QDSSCs.

Research paper thumbnail of Mesoporous ZnO/TiO2 photoanodes for quantum dot sensitized solar cell

Optical Materials, 2021

Abstract In the present work, different photoanodes, namely ZnO/TiO2 and bare TiO2 were deposited... more Abstract In the present work, different photoanodes, namely ZnO/TiO2 and bare TiO2 were deposited on fluorine-doped tin oxide (FTO) conductive glass substrate by the doctor blade method. CdS quantum dot was deposited on the photoanode by using the successive ionic layer adsorption and reaction (SILAR) method. In this, CuS was also coated on the FTO substrate which acts as the counter electrode. The structural, optical and electrical properties of deposited photoanodes and counter electrode were successfully investigated. The J-V characteristic and the other parameters of quantum dot sensitized solar cell (QDSSC) were analyzed by a using solar simulator under the illumination of a xenon short arc lamp an AM 1.5 G spectrum, having the light intensity of 100 mWcm−2. The power conversion efficiency of QDSSC using different photoanodes were compared. Due to the formation of energy barrier, ZnO/TiO2 using CdS QDs have higher efficiency ( 1.73%) as compared to bare TiO2 using CdS QDs ( 1.01%). It was found that ZnO/TiO2 based QDSSC exhibits 71% higher efficiency than that of TiO2 based QDSSC. The incident photon-to-current conversion efficiency (IPCE) obtained for ZnO/TiO2 electrode were approximately 46% (at 465 nm) and for bare TiO2 electrode around 34% (at 446 nm). The overall investigation supports the electron transport and enhanced performance of the ZnO/TiO2/CdS solar cell.

Research paper thumbnail of Hetro-nanostructured Se-ZnO sustained with RGO nanosheets for enhanced photocatalytic degradation of p-Chlorophenol, p-Nitrophenol and Methylene blue

Separation and Purification Technology, 2021

Abstract The persistent organic pollutants predominantly phenolic compounds and organic dyes are ... more Abstract The persistent organic pollutants predominantly phenolic compounds and organic dyes are the hazardous pollutants into the environment, considered as crucial contaminants in aquatic environment as well and cause to different severe detrimental impact on the human being and other living systems. In the present investigation, hetro-nanostructured Se-ZnO incorporated with different weight % of RGO (0, 1, 3, 5 and 8%) coded as SeZG-0, SeZG-1, SeZG-3, SeZG-5 and SeZG-8 nanocomposites were fabricated using a facile and simple refluxing method for the enhanced photocatalytic degradation and complete mineralization of phenolic compounds (p-Chlorophenol, p-Nitrophenol) and organic dye (methylene blue) via advanced oxidation technique. XRD, Raman, FT-IR, SEM and UV–Vis DRS techniques were used to determine the structural, morphological and optical properties of the synthesized nanocomposites comprehensively, respectively. p-chlorophenol, p-nitrophenol and methylene blue were considered as model organic pollutants in water for the assessment of photocatalytic performance of the SeZG nanocomposites and the mineralization efficiency was obtained 99.02, 98.89 and 99.41% under irradiation of UV light for 105 min, 90 min and 35 min, respectively. The outstanding photocatalytic performance of SeZG nanocomposites revealed by the significant obstruction in the recombination of charge carriers owing to the presence of Se and RGO nanosheets resulting production of additional reactive oxygen species and photodegradation of organic contaminants (p-chlorophenol, p-nitrophenol and methylene) from water. Finally, photodegradation mechanism is proposed.

Research paper thumbnail of Wrinkle type nanostructured Y-doped ZnO thin films for oxygen gas sensing at lower operating temperature

Materials Research Bulletin, 2021

Research paper thumbnail of ZnO-CdO Nanocomposites Incorporated With Graphene Oxide Nanosheets for Efficient Photocatalytic Degradation of Bisphenol A, Thymol Blue and Ciprofloxacin

Journal of Hazardous Materials, 2021

The widespread existence of different organic contaminants mostly phenolic compounds, organic dye... more The widespread existence of different organic contaminants mostly phenolic compounds, organic dyes and antibiotics in water bodies initiated by the various industrial wastes that raised great scientific concern and public awareness as well recently owing to their prospective capability to spread these contaminants resistant gene and pose hazard to human. In the present study, a series of nanostructured ZnO-CdO incorporated with reduced graphene oxide (ZCG nanocomposites) were successfully synthesized by a simple refluxing method and characterized by using the X-ray diffraction (XRD), Raman spectroscopy, FT-IR spectroscopy, photoluminescence spectroscopy, field emission-scanning microscope (FE-SEM) and UV-visible diffused reflectance spectroscopy (DRS) for the photocatalytic degradation of bisphenol A (BPA), thymol blue (ThB) and ciprofloxacin (CFn) with illumination of UV light. The maximum degradation and mineralization of BPA, ThB and CFn was achieved around 98.5%, 98.38% and 99.28% over the ZCG-5 nanocomposite photocatalyst after UV light irradiation for 180 min, 120 min and 75 min, respectively. The superior photocatalytic activity of ZCG-5 ascribed to enhance adsorption capacity, effective separation of charge carriers consequential for the production of more ROS after incorporation of RGO nanosheets with ZnO-CdO in photocatalyst. The conceivable photocatalytic degradation mechanism of BPA, ThB and CFn was elucidated through ROS identification and the assessment of photocatalyst stability by reusability, EEO (kwh/m3order) and UV light dose (mJ/cm2) were evaluated. The plausible photocatalytic degradation pathways were proposed for the degradation of BPA, ThB and CFn via GC-MS analysis. The present work investigates the efficient removal of BPA, ThB and CFn using ZCG nanocomposites as photocatalyst.

Research paper thumbnail of Chalcogen-doped zinc oxide nanoparticles for photocatalytic degradation of Rhodamine B under the irradiation of ultraviolet light

Materials Today Chemistry, 2021

Abstract In the present work, the chalcogen (Se2+)-doped ZnO nanoparticles (SeZO-NPs) were synthe... more Abstract In the present work, the chalcogen (Se2+)-doped ZnO nanoparticles (SeZO-NPs) were synthesized using sol-gel precipitation method and tested for photocatalytic degradation of Rhodamine B (RhB). X-ray diffraction pattern of SeZO-NPs showed the hexagonal wurtzite crystal structure regardless of Se concentration. The band edge and defect-level emissions of SeZO-NPs were determined by using the photoluminescence spectra with the excitation source of 370 nm. The bandgap, Eg, of SeZO-NPs was measured from diffused reflectance spectroscopy, which increased from 3.22 to 3.26 eV as Se concentration increased from 0 to 10 wt.%. The highest specific surface area and lowest pore size of 5-SeZO-NPs were observed to be 36.42 m2/g and 13.48 nm, respectively. The photocatalytic degradation of SeZO-NPs was measured under the illumination of ultraviolet (UV) light. The double donor (Se) played an important role toward photodegradation of RhB via reducing the recombination of charge carriers. The highest photocatalytic degradation (98.23%) and mineralization were achieved for the sample 5-SeZO (Se: 5 wt.%). The improved photocatalytic performance of 5-SeZO was attributed to the optimum Se dopant concentration for the production of more reactive oxygen species because of effective separation of charge carriers in UV light.

Research paper thumbnail of Improved stability of gas sensor by inclusion of Sb in nanostructured SnO2 thin films grown on sodalime

Journal of Alloys and Compounds, 2020

Abstract In the present work an attempt has been made to improve the stability in the oxygen gas ... more Abstract In the present work an attempt has been made to improve the stability in the oxygen gas sensing property of SnO2 with Sb doping using low cost sol-gel spin coating techniques. Un-doped and Sb (0, 0.5, 1.0, 1.5 and 2 at. %) doped SnO2 thin films were deposited on sodalime glass substrate by spin coating technique at 2500 rpm and annealed at 400 °C. The properties of thin films were investigated by their structural, morphological, optical and electrical analysis for oxygen gas sensing at low operating temperature. The crystalline phase and crystallite size were measured by X-ray diffraction pattern. It was observed that peaks show the polycrystalline nature with the tetragonal crystal structure. Scanning electron microscopic images revealed that all thin films have spherical type morphology. The transmittance spectra were recorded in the wavelength range 200–800 nm and optical band gap was varied from 3.56 eV to 3.92 eV with increasing doping concertation. The I–V measurements were recorded from −5 V to 5 V by two probe method. The highest conductivity was observed for 1 at. % Sb doped SnO2 thin film sample. The gas sensing properties of above thin films were measured as a function of operating temperature in the temperature range from 30 °C to 125 °C and the highest response was obtained for 1 at. % Sb doped SnO2 thin film sample. It has been observed from the experimental results that Sb doped SnO2 thin films exhibit the improved gas response, low operating temperature and good selectivity.