Structural and optical properties of vanadium doped SnO₂ nanoparticles with high photocatalytic activities

Reddy, Ch.V.,Babu, B.,Vattikuti, S.V.P.,Ravikumar, R.V.S.S.N.,Shim, J. Elsevier [etc.] 2016 Journal of luminescence Vol.179 No.-

Vanadium (0.01, 0.03 and 0.05mol%) doped SnO<SUB>2</SUB> nanoparticles have been synthesized using combustion synthesis method. The as-prepared nanoparticles were characterized using various measurements such as XRD, SEM with EDS, HRTEM, Raman spectroscopy, optical, PL, XPS and FT-IR techniques. The crystal structure and average particle sizes of the prepared nanoparticles were confirmed from the XRD. The average crystalline particle sizes were decreased by increasing the vanadium dopant concentration. The presence of vanadium as V<SUP>4+</SUP> species in the host lattice was confirmed by X-ray photoelectron spectroscopy. The band gap energies were decreased by increasing dopant concentration. The 0.05mol% doped sample showed higher photocatalytic activity than undoped, V-1 and V-3 in decomposing rhodamine B (RhB) under UV light irradiation. The Raman and IR spectra confirm the fundamental vibration of SnO<SUB>2</SUB> host molecules.

The influence of in situ deposition techniques on PbS seeded CdS/CdSe for enhancing the photovoltaic performance of quantum dot sensitized solar cells

Punnoose, D.,Suh, S.M.,Kim, B.J.,kim, S.k.,Kumar, Ch.S.S.P.,Rao, S.S.,Thulasi-Varma, C.V.,Reddy, A.E.,Chung, S.H.,Kim, H.J. Elsevier Sequoia 2016 Journal of Electroanalytical Chemistry Vol.773 No.-

<P>The deposition techniques of quantum dots (QDs) have great influence on the photovoltaic performances of quantum dot sensitised solar cells (QDSSCs). In this study, we report CdS/CdSe sensitised TiO2 solar cells focussing on the influence of two commonly used in situ QD deposition techniques (SILAR: successive ionic layer adsorption and reaction and CBD: chemical bath deposition). In addition to this, the QDSSC performance is enhanced due to better light harvesting capability of PbS quantum dots and makes large accumulation of photo-injected electrons in the conduction band of TiO2. When compared to power conversion efficiency (PCE) of 4.58% was obtained for PbS/CBD-CdS/CBD-CdSe cells when compared to PbS/SILAR-CdS/SILAR-CdSe. With chemical bath deposition, we achieved high surface coverage of QDs, which contributes to the increase in photocurrent,open circuit voltage and fill factor. Impedance spectroscopy revealed that the PbS/CBD-CdS/CBD-CdSe reduces recombination and increases charge collection efficiency and a long electron lifetime was achieved. To associate the assembling of QDs with the performance of QDSSCs a methodical characterization of morphology, optical and electro-chemical properties and its stability has been studied. We achieved PbS seeded CBD highlighting its robust consequences for the performance of QDSSCs. (C) 2016 Elsevier B.V. All rights reserved.</P>

An Innovative Method for Texture Classification Based on Random Threshold and Measure of Pattern Trends

B. V. Ramana Reddy,A. Suresh,K.V.Subbaiah,Dr.B. Eswara Reddy 보안공학연구지원센터 2009 International Journal of Hybrid Information Techno Vol.2 No.4

Study of different patterns on a local neighborhood of a texture plays an important role in characterization, and classification of the textures. The present paper proposes a method for measuring the occurrence factor of patterns on a randomly thresholded binary image. For this process eight simple patterns are chosen on a 3×3 neighborhood. The simple patterns are chosen in such a way that any complex pattern can be formed by grouping one or more of these simple patterns. The pattern occurrence factor of different binary images is also compared with the actual binary texture image. The experimental results on sixty four textures indicate good comparison of variation of occurrence in these patterns on different binary images of random threshold

Montmorillonite Clay Catalyzed Three Component, One-Pot Synthesis of 5-Hydroxyindole Derivatives

Reddy, B.V. Subba,Reddy, P. Sivaramakrishna,Reddy, Y. Jayasudhan,Bhaskar, N.,Reddy, B. Chandra Obula Korean Chemical Society 2013 Bulletin of the Korean Chemical Society Vol.34 No.10

A highly efficient and environmentally benign protocol has been developed for the first time to produce a wide range of biologically active 5-hydroxyindole derivatives using montmorillonite KSF clay as a reusable solid acid catalyst. The use of recyclable clay makes this procedure quite simple, more convenient and cost-effective.

Montmorillonite Clay Catalyzed Three Component, One-Pot Synthesis of 5-Hydroxyindole Derivatives

B. V. Subba Reddy,P. Sivaramakrishna Reddy,Y. Jayasudhan Reddy,N. Bhaskar,B. Chandra Obula Reddy 대한화학회 2013 Bulletin of the Korean Chemical Society Vol.34 No.10

A highly efficient and environmentally benign protocol has been developed for the first time to produce a wide range of biologically active 5-hydroxyindole derivatives using montmorillonite KSF clay as a reusable solid acid catalyst. The use of recyclable clay makes this procedure quite simple, more convenient and cost-effective.

Solution-based spin-coated tin sulfide thin films for photovoltaic and supercapacitor applications

Reddy, B. Purusottam,Sekhar, M. Chandra,Vattikuti, S.V. Prabhakar,Suh, Youngsuk,Park, Si-Hyun Elsevier 2018 Materials research bulletin Vol.103 No.-

<P><B>Abstract</B></P> <P>In this study, tin sulfide (SnS<SUB>x</SUB>) thin films were prepared using a solution-based spin-coating method. The annealing temperature was observed to play a dominant role in determining the phase, crystallinity, and morphology of the SnS<SUB>x</SUB> thin films. The results obtained from X-ray diffraction, as well as optical and electrical measurements, revealed that the films annealed at 500 °C exhibit a pure SnS phase, with a carrier concentration and direct band gap of ∼10<SUP>12</SUP> and 1.4 eV, respectively. To explore the applications of SnS in supercapacitors, electrochemical measurements were performed in a 0.2 M NaOH solution. The results indicated that films with a pure SnS phase have a high specific capacitance of 42 F g<SUP>―1</SUP> at a current density of 2 A g<SUP>―1</SUP>. The synthesized SnS thin films demonstrate potential for applications in electrochemical capacitors and solar cells.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Tin sulfide (SnS<SUB>x</SUB>) thin films were prepared by solution-based spin coating. </LI> <LI> The SnS<SUB>x</SUB> films annealed at 500 °C exhibited a pure SnS phase. </LI> <LI> The films exhibited direct band gap of 1.4 eV which is near to solar maximum. </LI> <LI> The films with the pure SnS phase exhibited a specific capacitance of 42 F g<SUP>―1</SUP>. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Carbon/CuO nanosphere-anchored g-C₃N₄ nanosheets as ternary electrode material for supercapacitors

Vattikuti, S.V. Prabhakar,Reddy, B. Purusottam,Byon, Chan,Shim, Jaesool Elsevier 2018 Journal of solid state chemistry Vol.262 No.-

<P><B>Abstract</B></P> <P>Novel electrode materials for supercapacitors comprised of carbon and copper oxide (CuO) nanospheres on graphitic carbon nitride (g-C<SUB>3</SUB>N<SUB>4</SUB>) nanosheets, denoted as C/CuO@g-C<SUB>3</SUB>N<SUB>4</SUB> are self-assembled via a one-step co-pyrolysis decomposition method. The pure g-C<SUB>3</SUB>N<SUB>4</SUB> and C/CuO@g-C<SUB>3</SUB>N<SUB>4</SUB> were confirmed by powder X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), thermal gravimetric and differential thermal analysis (TG-DTA), X-ray photoelectron spectroscopy (XPS), N<SUB>2</SUB> adsorption/desorption studies and Fourier-transform infrared spectroscopy (FTIR). The specific capacitance was 247.2 F g<SUP>−1</SUP> in 0.5 M NaOH at a current density of 1 A g<SUP>−1</SUP>, and more than 92.1% of the capacitance was retained after 6000 cycles. The property enhancement was ascribed to the synergistic effects of the three components in the composite. These results suggest that C/CuO@g-C<SUB>3</SUB>N<SUB>4</SUB> possessed an excellent cyclic stability with respect to their capacity performance as electrode materials.</P> <P><B>Highlights</B></P> <P> <UL> <LI> An efficient C/CuO@g-C<SUB>3</SUB>N<SUB>4</SUB> supercapacitor electrode was synthesized. </LI> <LI> A ternary hybrid was developed via co-pyrolysis in situ growth. </LI> <LI> The C/CuO@g-C<SUB>3</SUB>N<SUB>4</SUB> hybrid exhibits a 247.2 F g<SUP>−1</SUP> at scan rate of 1 Ag<SUP>−1</SUP>. </LI> <LI> Fast charge transfer was observed over the C/CuO@g-C<SUB>3</SUB>N<SUB>4</SUB> hybrid. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Role of molybdenum trioxide in enhancing the humidity sensing performance of magnesium ferrite/molybdenum trioxide composite

Babu Reddy, L.P.,Megha, R.,Chethan, B.,Raj Prakash, H.G.,Ravikiran, Y.T.,Ramana, C.H.V.V.,Kim, D. ELSEVIER 2018 INORGANIC CHEMISTRY COMMUNICATIONS Vol.98 No.-

<P><B>Abstract</B></P> <P>In the present work, we prepared magnesium ferrite/molybdenum trioxide (MFMO) nanocomposite using mechano chemical mixing method for humidity sensor at room temperature. Enhancement in active sites for water adsorption in the composite due to the presence of MoO<SUB>3</SUB> confirmed from X-ray diffraction (XRD) studies. Change in grain size distribution and increase in intergranular pores in the composite favouring water adsorption confirmed from its scanning electron microscopy (SEM) image. Increased agglomeration of nano sized particles and improved crystallinity of the composite confirmed from Transmission electron microscopy (TEM) studies and selected area electron diffraction (SAED) pattern. The composite showed maximum sensing response of 4902 as against 183 of MF in the range 11%–97% RH. The response and recovery times of the composite were found to be 45 s and 74 s respectively while those of MF 225 s and 364 s respectively. The nanocomposite sample showed stable humidity sensing ability and a low humidity hysteresis. Molybdenum trioxide plays a major role in enhancing the humidity sensing performance of MFMO composite at room temperature. The sensing mechanism discussed on the basis of chemisorptions, physisorption and capillary condensation processes.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Humidity sensing response of magnisium ferrite (MF) and magnesium ferrite-molybdenum trioxide (MFMO) composite presented. </LI> <LI> The MFMO showed maximum sensing response of 4902 as against 183 of MF in the range 11%-97% RH. </LI> <LI> The response and recovery times of the composite were found to be 45 s and 74 s respectively. </LI> <LI> The sensing mechanism MFMO discussed on the basis of chemisorptions, physisorption and capillary condensation processes. </LI> </UL> </P>

Effects of Annealing on Electrical Characteristics and Current Transport Mechanisms of the Y/p-GaN Schottky Diode

Reddy, V. R.,Asha, B.,Choi, C. J. Springer Science + Business Media 2016 Journal of electronic materials Vol.45 No.7

<P>This study investigates the effects of annealing on the electrical properties and current transport mechanism of Y/p-GaN Schottky barrier diodes (SBDs). We found no significant change in the surface morphology of the Y Schottky contacts during the annealing process. The Schottky barrier height (SBH) of the as-deposited Y/p-GaN SBD was estimated to be 0.95 eV (I-V)/1.19 eV (C-V). The SBH increased upon annealing at 400A degrees C and 500A degrees C, and then decreased slightly with annealing at 600A degrees C. Thus the maximum SBH of the Y/p-GaN SBD was achieved at 500A degrees C, with values of 1.01 eV (I-V)/1.29 eV (C-V). In addition, the SBH values were estimated by Cheung's, Norde, and I-s-V plots and were found to be in good agreement with one another. Series resistance (R (S)) values were also calculated by I-V, Cheung's, and Norde functions at different annealing temperatures, with results showing a decrease in the interface state density of the SBD with annealing at 500A degrees C, followed by a slight increase upon annealing at 600A degrees C. The forward-bias current transport mechanism of SBD was investigated by the logI-logV plot at different annealing temperatures. Our investigations revealed that the Poole-Frenkel emission mechanism dominated the reverse leakage current in Y/p-GaN SBD at all annealing temperatures.</P>

Electrical transport properties of Au/SiO2/n-GaN MIS structure in a wide temperature range

B. Prasanna Lakshmi,M. Siva Pratap Reddy,A. Ashok Kumar,V. Rajagopal Reddy 한국물리학회 2012 Current Applied Physics Vol.12 No.3

The temperature-dependent electrical properties of Au/SiO2/n-GaN metal-insulator-semiconductor (MIS)structure have been investigated in the temperature range of 120e390 K. Anomalous strong temperature dependencies of the barrier height (φbo), ideality factor (n), interface state density (NSS) and series resistance (RS) are obtained. Such behaviour is attributed to barrier inhomogeneities by assuming a Gaussian distribution of barrier heights (GD BHs) at the interface. It is evident that the diode parameters such as zero-bias barrier height increases and the ideality factor decreases with increasing temperature. The values of series resistance that are obtained from Cheung’s method is decreasing with increasing in temperature. The temperature-dependent currentevoltage characteristics of the MIS diode have been shown a double Gaussian distribution giving mean barrier heights of 0.38 eV and 1.06 eV and standard deviations of 0.0561 and 0.2742 V, respectively. A modified ln (Io/T2) - q2so 2/2k2T2 versus 103/T plot for the two temperature regions gives 4bo and A* as 0.55 eV and 11.56 A cm-2 K-2, and 1.02 eV and 23.48 A cm-2 K-2 respectively. The Interface state density values are calculated by IeV and CeV measurements at different temperatures using Terman’s method. It is observed that the interface state density decreases with increase in temperature (120e390 K). Therefore, it has been concluded that the temperature dependence of the forward IeV characteristics of the Au/SiO2/n-GaN Schottky diodes can be explained with a double GD of the BHs.