Systematic studies of Bi₂O₃ hierarchical nanostructural and plasmonic effect on photoelectrochemical activity under visible light irradiation

Reddy, I. Neelakanta,Reddy, Ch. Venkata,Sreedhar, Adem,Cho, Migyung,Kim, Dongseob,Shim, Jaesool Elsevier 2019 CERAMICS INTERNATIONAL Vol.45 No.14

<P><B>Abstract</B></P> <P>The effect of Ag plasmonic nanowire layers on the hierarchical nanostructure of Bi<SUB>2</SUB>O<SUB>3</SUB> photoelectrodes for water splitting under visible light irradiation was studied for the first time. In addition, the impact of various Bi<SUB>2</SUB>O<SUB>3</SUB> nanostructures on light harvesting and generation of relative photocurrent have been investigated. The cubic structure of Bi<SUB>2</SUB>O<SUB>3</SUB> was confirmed using X-ray diffraction analysis. Optical bandgaps of 2.14 and 2.30 eV have been achieved for the Bi<SUB>2</SUB>O<SUB>3</SUB> nanoparticles and nanoflowers photoelectrodes (BP and BF), respectively. The photocurrent density (J) of the BP featuring Ag plasmonic layer photoelectrode (Ag/BP) was 6.47 mA cm<SUP>−2</SUP>, and was higher than that of the BF featuring Ag plasmonic layer photoelectrode (Ag/BF), which was 4.33 mA cm<SUP>−2</SUP>. These values were approximately 647 and 2165 times higher than those of BP and BF, respectively. However, the J value of BP was 2.13 mA cm<SUP>−2</SUP> higher than that of BF. The superior J values of Ag/BP and Ag/BF were attributed to the increased light absorption and reduced electron-hole recombination rate at the time scale beyond a few 10<SUP>−12</SUP> s, owing to the Ag nanowires. In addition, the plasmonic field was able to reduce the charge recombination rate of the nanostructured electrodes in reactor cells.</P>

Inhibitory Activity of Pseudomonas putida and Bacillus licheniformis Supernatants on PMMoV in Chili Pepper

Venkata Subba Reddy Gangireddygari,조인숙,최세나,윤주연 인간식물환경학회 2023 인간식물환경학회지 Vol.26 No.1

Background and objective: Plant viruses are major obstacles to enhancing crop productivity in both agriculture and horticulture throughout the world, resulting in losses of several billion dollars every year. Controlling viruses is arduous, so agrochemicals are widespread. To minimize the usage of those, this study's objective was to assess bacterial cultures supernatants on pepper mild mottle virus (PMMoV) in chili pepper plants and identify its secondary metabolites. Methods: This 48-h grown Pseudomonas putida (PP) and Bacillus licheniformis (BL) cultures supernatants were foliar sprayed separately in chili pepper plants 24-h before PMMoV inoculation (T1), and 24-h before and after PMMoV inoculation (T2), 2wpi (week's post inoculation), the virus titer was determined by using a double antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA), and the supernatants were extracted with ethyl acetate and concentrated by rota-evaporation before being analyzed in gas chromatography mass spectrometry (GC-MS). Results: The culture supernatants of PP and BL inhibit PMMoV by 43-47% in both the treatments (T1 & T2) compared to the control. The GC-MS chromatogram of two cultures of supernatants identified the molecules of cyclo (Pro-Val), cyclo (Pro-Leu), and cyclo (Phe-Pro). Commercial forms of these three molecules at three concentrations showed a hypersensitive response, ranging from 45-65% for PMMoV in Nicotiana glutinosa. Conclusion: The results revealed that supernatants of PP and BL-containing compounds have biological control of PMMoV in chili pepper plants.

Inhibitory Effect of Chitosan and Phosphate Cross-linked Chitosan against Cucumber Mosaic Virus and Pepper Mild Mottle Virus

Venkata Subba Reddy Gangireddygari,Bong Nam Chung,In-Sook Cho,Ju-Yeon Yoon 한국식물병리학회 2021 Plant Pathology Journal Vol.37 No.6

Cucumber mosaic virus (CMV) and Pepper mild mot- tle virus (PMMoV) causes severe economic loss in crop productivity of both agriculture and horticulture crops in Korea. The previous surveys showed that naturally available biopolymer material – chitosan (CS), which is from shrimp cells, reduced CMV accumulation on pepper. To improve the antiviral activity of CS, it was synthesized to form phosphate cross-linked chitosan (PCS) and compared with the original CS. Initially, the activity of CS and PCS (0.01%, 0.05%, and 0.1% con- centration) compound against PMMoV infection and replication was tested using a half-leaf assay on Nico- tiana glutinosa leaves. The total number of local lesions represented on a leaf of N. glutinosa were counted and analyzed with phosphate buffer treated leaves as a neg- ative control. The leaves treated with a 0.1% concentra- tion of CS or PCS compounds exhibited an inhibition effect by 40-75% compared with the control leaves. The same treatment significantly reduced about 40% CMV accumulation measured by double antibody sandwich enzyme-linked immunosorbent assay and increased the relative expression levels of the NPR1, PR-1, cysteine protease inhibitor gene, LOX, PAL, SRC2, CRF3 and ERF4 genes analyzed by quantitative reverse transcrip- tase-polymerase chain reaction, in chili pepper plants.

Enhanced hydrogen production activity over BiO X TiO 2 under solar irradiation: Improved charge transfer through bismuth oxide clusters

Reddy, Police Anil Kumar,Manvitha, Chennaiahgari,Reddy, Pullagurala Venkata Laxma,Kim, Ki-Hyun,Kumari, Valluri Durga Elsevier Inc 2017 Journal of Energy Chemistry Vol.26 No.3

<P>A series of titania nanoparticles and nanotubes deposited with various quantities of bismuth (Bi) were prepared via sol-gel and hydrothermal methods, respectively. They were then characterized using X-ray diffraction spectroscopy (XRD), X-ray photo electron spectroscopy (XPS), UV-Vis diffused reflectance spectra (DRS), photoluminescence spectra (PLS), transmission electron microscopy (TEM), energy dispersive analysis of X-rays (EDAX), and BET surface analysis. These catalysts were employed for the photocatalytic production of hydrogen from a mixture of pure water and glycerol under solar light irradiation. The presence of the Bi(3 + x)+ species was found to play a vital role in enhancing activity while minimizing electron hole recombination (relative to bare TiO2). The nanotubes exhibited better activity than the nanoparticles of Bi-deposited TiO2, showing the significance of the morphology; however, photocatalytic activity is predominantly dependent on the deposition of bismuth. The activity increased by approximately an order of magnitude at the optimum concentration of Bi deposited over TiO2 (2 wt%). The presence of the Bi(3 + x)+ species played a vital role in minimizing electron hole recombination, resulting in higher activity compared to bare TiO2. (C) 2016 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights reserved.</P>

Structural, optical, and improved photocatalytic properties of CdS/SnO₂ hybrid photocatalyst nanostructure

Venkata Reddy, Ch.,Ravikumar, R.V.S.S.N.,Srinivas, G.,Shim, J.,Cho, M. Elsevier 2017 Materials science and engineering B. Advanced Func Vol.221 No.-

<P>CdS, SnO2 and CdS/SnO2 hybrid photocatalyst nanostructure were synthesized using a two-step (co-pre cipitation/hydrothermal) method. The as-prepared materials were characterized by powder X-ray diffraction, transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), surface analysis (BET), photoluminescence spectra (PL), UV-Vis diffusion reflectance spectroscopy (DRS), fourier transform infrared spectroscopy (FT-IR), and photocatalytic activity. The band gap energies calculated from the DRS results are 3.30, 2.15, and 2.99 eV for pristine SnO2, CdS, and the CdS/SnO2 hybrid photocatalyst, respectively. The CdS/SnO2 hybrid photocatalyst showed more efficient charge carrier separation and improved photocatalytic degradation of methyl orange (MO). The highest degradation rate constant was achieved for the CdS/SnO2 hybrid photocatalyst (0.02434 min(-1)) compared to CdS (0.01381 min(-1)) and SnO2 (0.00878 min(-1)). The present study provides insights for improving the photocatalytic activity and photo-stability of CdS/SnO2 hybrid photocatalyst. (C) 2017 Elsevier B.V. All rights reserved.</P>

Effect of ball milling on optical properties and visible photocatalytic activity of Fe doped ZnO nanoparticles

Reddy, I. Neelakanta,Reddy, Ch. Venkata,Sreedhar, M.,Shim, Jaesool,Cho, Migyung,Kim, Dongseob Elsevier 2019 Materials science and engineering B. Advanced Func Vol.240 No.-

<P><B>Abstract</B></P> <P>The Fe doped ZnO nanoparticles were prepared using high-energy ball milling technique. The X-ray diffraction was utilized to study the effect of ball milling time on the crystalline structure. Field emission scanning electron microscopy was used to analyze the morphology of Fe doped ZnO. The intensity of the peaks decreases with the ball milling time and also no evidence was found the appearance of Fe<SUB>3</SUB>O<SUB>4</SUB> peaks at above 30 h, indicates a decrement in crystallinity owing to the incorporation of Fe into ZnO sites and it confirmed through peak shift in phase analysis. The electron structure was studied by X-ray photoelectron spectroscopy. It was observed that the both Zn and Fe are in 2+ oxidation state. The effect of milling time on optical properties and photocatalytic activity of Fe doped ZnO was determined using UV–visible spectrophotometry. Photocatalytic efficiency of the prepared samples was estimated by degradation of methylene orange dye in aqueous solution under sunlight irradiation. Maximum degradation of ∼98.7% for MO was achieved using 40 h ball milled Fe doped ZnO nanoparticles.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Fe doped ZnO nanoparticle was successfully grown by ball milling. </LI> <LI> The lowest bandgap of 2.55 eV was achieved for 40 h milled Fe doped ZnO sample. </LI> <LI> Fe doped ZnO nanoparticles exhibited high the visible light absorption properties. </LI> <LI> Maximum degradation of ∼98.7% for MO was observed under solar light irradiation. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Photocatalytic degradation of bisphenol A in aqueous media: A review

Reddy, P. Venkata Laxma,Kim, Ki-Hyun,Kavitha, Beluri,Kumar, Vanish,Raza, Nadeem,Kalagara, Sudhakar Elsevier 2018 Journal of environmental management Vol.213 No.-

<P><B>Abstract</B></P> <P>Bisphenol A (BPA) is known to be an emerging pollutant in various environmental compartments. Human exposure to BPA occurs widely because it is commonly used as the raw material in a variety of industrial processes (e.g., the preparation of epoxy and polycarbonate resins). In this review, a brief survey was carried out to cover a range of photocatalytic materials (e.g., titania, zinc, silver, carbon, and bismuth) and their modified forms as an effective means to treat water systems contaminated with BPA. The overall efficiency and limitations of these catalysts are described for the photocatalytic treatment of BPA.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Bisphenol A [BPA] is a rapidly emerging pollutant in the ambient environment. </LI> <LI> BPA removal through application of photocatalysis has been explored intensively. </LI> <LI> Competence of Ti, Zn, Ag, Bi, and C-based photocatalysts are discussed. </LI> <LI> Combination of hydroxyl radical (OH) and photogenerated holes is crucial in BPA removal. </LI> </UL> </P>

Effect of plasmonic Ag nanowires on the photocatalytic activity of Cu doped Fe₂O₃ nanostructures photoanodes for superior photoelectrochemical water splitting applications

Reddy, I. Neelakanta,Reddy, Ch. Venkata,Sreedhar, Adem,Cho, Migyung,Kim, Dongseob,Shim, Jaesool Elsevier 2019 Journal of electroanalytical chemistry Vol.842 No.-

<P><B>Abstract</B></P> <P>The Present study focuses on the synthesis and analysis of Cu doped hematite (α-Fe<SUB>2</SUB>O<SUB>3</SUB>) nanostructures for effectively enhancing the optical properties as well as their implementation as photoelectrodes for energy-harvesting applications. In addition to this, the influence of noble metal plasmonic layer of Ag nanowires as a bottom layer for undoped and doped Fe<SUB>2</SUB>O<SUB>3</SUB> photoanodes has been investigated. Herein, we studied the influence of dopant on morphology, structural, and optical properties of Fe<SUB>2</SUB>O<SUB>3</SUB>. X-ray diffraction technique and X-ray photoelectron spectroscopy analysis were confirmed Cu ion substitution into host Fe<SUB>2</SUB>O<SUB>3</SUB> nanostructures. The optical band gap decreases from ~ 1.95eV to ~ 1.38eV with increasing of Cu dopant concentration. Impedance analysis reveals that the Cu dopant works as an electron donor and improves the Fe<SUB>2</SUB>O<SUB>3</SUB> charge carrier density. The photoelectrochemical water splitting studies reveals that the photoanodes without plasmonic layer was shown improved photocurrents compare to the undoped sample, thus improving the absorption of the incident light. Significantly, the optimized 0.2mol% Cu-doped α-Fe<SUB>2</SUB>O<SUB>3</SUB> photoelectrodes without Ag layer reached the maximum photocurrent density of ~0.31mA/cm<SUP>2</SUP>, ~ 28-fold that of pure Fe<SUB>2</SUB>O<SUB>3</SUB> (0.011mA/cm<SUP>2</SUP>). Further, the same photoanode with plasmonic Ag nanowires showed a significantly improved photocurrent density of 1.48mA/cm<SUP>2</SUP>, which is ~ 135-fold that of pure Fe<SUB>2</SUB>O<SUB>3</SUB> and ~ 5-folds that of 0.2mol% Cu doped α-Fe<SUB>2</SUB>O<SUB>3</SUB> photoelectrodes without plasmonic nanowire layer. The superior photocurrent is ascribed to the enhanced electron donor density and reduced charge recombination rate, as an outcome of optimized Cu doping and Ag nanowires.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Cu-doped Fe<SUB>2</SUB>O<SUB>3</SUB> and Ag plasmonic nanostructures were synthesized by hydrothermal and polyol methods. </LI> <LI> Optimal 0.2mol% Cu doped Fe<SUB>2</SUB>O<SUB>3</SUB> photoanode showed the highest photocurrent density of 1.48mA/cm<SUP>2</SUP>. </LI> <LI> Photoanode with Ag plasmonic increases the photocurrents of 135-fold that of pure Fe<SUB>2</SUB>O<SUB>3</SUB>. </LI> <LI> Excellent photoelectrochemical water splitting activity was achieved. </LI> </UL> </P>

Synthesis of CdO/ZnS heterojunction for photodegradation of organic dye molecules

Venkata Reddy, Ch.,Bandaru, Narendra,Shim, Jaesool,Vattikuti, S. V. Prabhakar Springer-Verlag 2017 APPLIED PHYSICS A MATERIALS SCIENCE AND PROCESSING Vol.123 No.6

A Review of Photocatalytic Treatment for Various Air Pollutants

Reddy, P. Venkata Laxma,Kim, Ki-Hyun,Kim, Yong-Hyun Korean Society for Atmospheric Environment 2011 Asian Journal of Atmospheric Environment (AJAE) Vol.5 No.3

Photocatalysis is a photochemical catalytic reaction which is a highly promising tool for the environmental cleanup process. It is very effective in treatment of environmental pollutants by its unique redox property. It has wide applications in the treatment of atmospheric pollutants (e.g., nitrogen dioxide, trichloroethylene, volatile organics, hydrogen sulfide, benzene, etc) through oxidative removal and by disinfection (aeromicro flora). In this research, the fundamental aspects of photocatalysis are described with respect to the composition of catalysts, experimental conditions (e.g., temperature, duration, etc), and interfering factors (e.g., catalyst deactivation).