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Papers by juliat josephine

Crystal Research and Technology, 2018

The high‐efficient and visible‐light active monoclinic BiVO4 thin films with preferentially orien... more The high‐efficient and visible‐light active monoclinic BiVO4 thin films with preferentially oriented (020) facets are successfully deposited by nebulizer spray pyrolysis technique. The role of substrate temperature over crystal growth facets and other physical properties of BiVO4 films are analyzed using XRD, HRTEM, UV spectrometer, and Raman analysis. The BiVO4 thin film deposited at 350 °C possesses broad absorbance in the visible region with highly exposed (020) facet is obtained. Room temperature photoluminescence analysis is used to understand the effective charge separation of photogenerated electron‐hole pair in BiVO4 thin films. It is worth to mention that the obtained monoclinic scheelite BiVO4 film with preferentially oriented (020) facet has large surface areas to produce greater number of reactive hydroxyl radicals, for the effective photocatalytic degradation of rhodamine B dye. Total organic content (TOC) study is conducted to examine the mineralization of organic compounds present in rhodamine B dye.

Materials Science in Semiconductor Processing, 2015

Abstract We report the synthesis of bismuth vanadate (BiVO4) nanostructure by atoxic-free, inexpe... more Abstract We report the synthesis of bismuth vanadate (BiVO4) nanostructure by atoxic-free, inexpensive co-precipitation method. The BiVO4 nanostructures were derived from bismuth nitrate and ammonia metavanadate as starting precursors and sodium hydroxide (NaOH) were used as stabilizers for tuning the morphology (nanorod, nanospheriod and nanoparticulate). The influence of post-calcination treatment (450, 550 and 650 °C) on structural, optical and photocatalytic properties of BiVO4 was studied. The post-calcination treatment strongly induces the crystallization process and produce monoclinic BiVO4 structure with predominant (112) crystallite phases. The absorbance of BiVO4 shows broad coverage of visible light wavelength region up to 550 nm, which is appreciable for solar light driven photocatalysis. Among the different calcinated samples, anisotropy rod-shape BiVO4 (calcinated at 450 °C) shows high optical absorbance than other treated (550 and 650 °C) samples. The monotonic shift in characteristic Raman vibration mode at 824 cm−1 with increasing calcination temperature indicates that the V–O bond length is affected by Bi3+ diffusivity. The PL spectra of these samples explore the intrinsic defects present in BiVO4, and found to be high in high temperature calcinated samples. The photocatalytic property of resultant BiVO4 samples was evaluated in oxygen generation with Ag+ donors. As a result of reduced defects and high optical absorbance, the BiVO4 calcinated at 450 °C showed high photocatalytic oxygen yield (1.02 mmol) compared with high temperature calcinated samples (0.48 mmol).The appreciable quantity of solar fuel O2 generation from the low-cost co-precipitation method can be widely implemented in other visible light metal oxide nanostructures.

Springer Proceedings in Physics, 2017

CuInS2 (CIS ) thin films were fabricated by jet nebulizer spray technique at various substrate te... more CuInS2 (CIS ) thin films were fabricated by jet nebulizer spray technique at various substrate temperatures such as 250, 300, 350 and 400 °C. The XRD revealed the formation of chalcopyrite crystalline phase with (1 1 2) preferential orientation. The film prepared at 300 °C has better crystallinity with minimum dislocation density and strain. The microstructure of the prepared CIS thin films was investigated by means of scanning electron microscope (SEM ). The elemental quantification and stoichiometric ratio of the CIS films were confirmed by EDS. The conductivity of CIS thin films was carried out by four probe method and it showed that all the films were in semiconducting nature. The optical band gap was found using Tauc plot and it was varied from 1.3 to 1.45 eV. A peak around 298 cm−1 was observed in Raman spectra attributed to the mixture of both CH- and CA-ordering.

Springer Proceedings in Physics

Aluminium doped zinc oxide (AZO) nano-structured films were deposited by nebulizer spray techniqu... more Aluminium doped zinc oxide (AZO) nano-structured films were deposited by nebulizer spray technique. The role of aluminium dopant concentration over the structural, optical and electrical properties was examined by different analytical techniques. The structural results from X-ray diffraction showed that preferential orientation of films obtained along the (002) direction. The surface morphology of the films showed a hexagonal facet with the nano-structured film. The parameters such as resistivity and activation energy were determined from electrical studies. The sensitivity of the films towards ethanol gas was investigated at room temperature.

The present study reports on facile deposition of single-phase BiVO4 thin films by nebulizer spra... more The present study reports on facile deposition of single-phase BiVO4 thin films by nebulizer spray pyrolysis route for different spray volumes (5, 10, 15, and 20 ml). The main objective is to identify the optimum thickness and morphology of BiVO4 films for enhanced photocatalytic performance. The physical properties of the films were characterized using different analytical techniques. Highly compact and flake-like structures in BiVO4 film were resulted for higher spray volume without any aid of additive or template in the preparation procedure. Nanoflake BiVO4 film possessed high optical absorption, effective charge carrier transport properties, and high penetration depth, and exhibited maximum photodegradation efficiency for the treatment of rhodamine B and methyl orange dyes.

BiVO4 thin films were deposited on glass substrates using nebulizer spray deposition route for di... more BiVO4 thin films were deposited on glass substrates using nebulizer spray deposition route for different precursor solution aging period. The effect of the solution aging on structural, optical and chemical composition was investigated through different analytical techniques such as X-ray diffraction (XRD), scanning electron microscope (SEM), Raman, UV–Visible spectrometer, photoluminescence (PL) and Energy Dispersive X - ray analysis (EDX). It was observed that aging time of precursor solution strongly affects the growth of preferred orientation and morphology of as-deposited BiVO4 thin films. The photocatalytic performance of the deposited BiVO4 films was studied under visible light dye degradation experiments with rhodamine B (RhB) as test effluent. The photocatalytic experiments revealed that BiVO4 thin films deposited from aged solution exhibited better activity. The recycle tests were also conducted to analyze the chemical stability and reusability of the optimum BiVO4 film in...

Bismuth vanadate (BiVO 4) nanoparticles were synthesized by a simple co-precipitation method for ... more Bismuth vanadate (BiVO 4) nanoparticles were synthesized by a simple co-precipitation method for different pH conditions (9, 10 and 11). The XRD patterns revealed that the synthesized nanoparticles belong to monoclinic single-phase BiVO 4 which was again confirmed from Raman studies. The chemical state of the elements in BiVO 4 and surface morphology were investigated using XPS and SEM analysis respectively. The optical absorption and PL studies revealed wide absorption in the visible region with strong emission at 520 nm. The efficiency of the samples was examined from the photocatalytic degradation of Rhodamine B dye.

Crystal Research and Technology, 2018

The high‐efficient and visible‐light active monoclinic BiVO4 thin films with preferentially orien... more The high‐efficient and visible‐light active monoclinic BiVO4 thin films with preferentially oriented (020) facets are successfully deposited by nebulizer spray pyrolysis technique. The role of substrate temperature over crystal growth facets and other physical properties of BiVO4 films are analyzed using XRD, HRTEM, UV spectrometer, and Raman analysis. The BiVO4 thin film deposited at 350 °C possesses broad absorbance in the visible region with highly exposed (020) facet is obtained. Room temperature photoluminescence analysis is used to understand the effective charge separation of photogenerated electron‐hole pair in BiVO4 thin films. It is worth to mention that the obtained monoclinic scheelite BiVO4 film with preferentially oriented (020) facet has large surface areas to produce greater number of reactive hydroxyl radicals, for the effective photocatalytic degradation of rhodamine B dye. Total organic content (TOC) study is conducted to examine the mineralization of organic compounds present in rhodamine B dye.

Materials Science in Semiconductor Processing, 2015

Abstract We report the synthesis of bismuth vanadate (BiVO4) nanostructure by atoxic-free, inexpe... more Abstract We report the synthesis of bismuth vanadate (BiVO4) nanostructure by atoxic-free, inexpensive co-precipitation method. The BiVO4 nanostructures were derived from bismuth nitrate and ammonia metavanadate as starting precursors and sodium hydroxide (NaOH) were used as stabilizers for tuning the morphology (nanorod, nanospheriod and nanoparticulate). The influence of post-calcination treatment (450, 550 and 650 °C) on structural, optical and photocatalytic properties of BiVO4 was studied. The post-calcination treatment strongly induces the crystallization process and produce monoclinic BiVO4 structure with predominant (112) crystallite phases. The absorbance of BiVO4 shows broad coverage of visible light wavelength region up to 550 nm, which is appreciable for solar light driven photocatalysis. Among the different calcinated samples, anisotropy rod-shape BiVO4 (calcinated at 450 °C) shows high optical absorbance than other treated (550 and 650 °C) samples. The monotonic shift in characteristic Raman vibration mode at 824 cm−1 with increasing calcination temperature indicates that the V–O bond length is affected by Bi3+ diffusivity. The PL spectra of these samples explore the intrinsic defects present in BiVO4, and found to be high in high temperature calcinated samples. The photocatalytic property of resultant BiVO4 samples was evaluated in oxygen generation with Ag+ donors. As a result of reduced defects and high optical absorbance, the BiVO4 calcinated at 450 °C showed high photocatalytic oxygen yield (1.02 mmol) compared with high temperature calcinated samples (0.48 mmol).The appreciable quantity of solar fuel O2 generation from the low-cost co-precipitation method can be widely implemented in other visible light metal oxide nanostructures.

Springer Proceedings in Physics, 2017

CuInS2 (CIS ) thin films were fabricated by jet nebulizer spray technique at various substrate te... more CuInS2 (CIS ) thin films were fabricated by jet nebulizer spray technique at various substrate temperatures such as 250, 300, 350 and 400 °C. The XRD revealed the formation of chalcopyrite crystalline phase with (1 1 2) preferential orientation. The film prepared at 300 °C has better crystallinity with minimum dislocation density and strain. The microstructure of the prepared CIS thin films was investigated by means of scanning electron microscope (SEM ). The elemental quantification and stoichiometric ratio of the CIS films were confirmed by EDS. The conductivity of CIS thin films was carried out by four probe method and it showed that all the films were in semiconducting nature. The optical band gap was found using Tauc plot and it was varied from 1.3 to 1.45 eV. A peak around 298 cm−1 was observed in Raman spectra attributed to the mixture of both CH- and CA-ordering.

Springer Proceedings in Physics

Aluminium doped zinc oxide (AZO) nano-structured films were deposited by nebulizer spray techniqu... more Aluminium doped zinc oxide (AZO) nano-structured films were deposited by nebulizer spray technique. The role of aluminium dopant concentration over the structural, optical and electrical properties was examined by different analytical techniques. The structural results from X-ray diffraction showed that preferential orientation of films obtained along the (002) direction. The surface morphology of the films showed a hexagonal facet with the nano-structured film. The parameters such as resistivity and activation energy were determined from electrical studies. The sensitivity of the films towards ethanol gas was investigated at room temperature.

The present study reports on facile deposition of single-phase BiVO4 thin films by nebulizer spra... more The present study reports on facile deposition of single-phase BiVO4 thin films by nebulizer spray pyrolysis route for different spray volumes (5, 10, 15, and 20 ml). The main objective is to identify the optimum thickness and morphology of BiVO4 films for enhanced photocatalytic performance. The physical properties of the films were characterized using different analytical techniques. Highly compact and flake-like structures in BiVO4 film were resulted for higher spray volume without any aid of additive or template in the preparation procedure. Nanoflake BiVO4 film possessed high optical absorption, effective charge carrier transport properties, and high penetration depth, and exhibited maximum photodegradation efficiency for the treatment of rhodamine B and methyl orange dyes.

BiVO4 thin films were deposited on glass substrates using nebulizer spray deposition route for di... more BiVO4 thin films were deposited on glass substrates using nebulizer spray deposition route for different precursor solution aging period. The effect of the solution aging on structural, optical and chemical composition was investigated through different analytical techniques such as X-ray diffraction (XRD), scanning electron microscope (SEM), Raman, UV–Visible spectrometer, photoluminescence (PL) and Energy Dispersive X - ray analysis (EDX). It was observed that aging time of precursor solution strongly affects the growth of preferred orientation and morphology of as-deposited BiVO4 thin films. The photocatalytic performance of the deposited BiVO4 films was studied under visible light dye degradation experiments with rhodamine B (RhB) as test effluent. The photocatalytic experiments revealed that BiVO4 thin films deposited from aged solution exhibited better activity. The recycle tests were also conducted to analyze the chemical stability and reusability of the optimum BiVO4 film in...

Bismuth vanadate (BiVO 4) nanoparticles were synthesized by a simple co-precipitation method for ... more Bismuth vanadate (BiVO 4) nanoparticles were synthesized by a simple co-precipitation method for different pH conditions (9, 10 and 11). The XRD patterns revealed that the synthesized nanoparticles belong to monoclinic single-phase BiVO 4 which was again confirmed from Raman studies. The chemical state of the elements in BiVO 4 and surface morphology were investigated using XPS and SEM analysis respectively. The optical absorption and PL studies revealed wide absorption in the visible region with strong emission at 520 nm. The efficiency of the samples was examined from the photocatalytic degradation of Rhodamine B dye.