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>

Copolymerization of N-Vinyl Pyrrolidone with Functionalized Vinyl Monomers

S. Vijaykumar,S. Prasannkumar,B. S. Sherigara,N. B. Shelke,Tejraj M. Aminabhavi,B. S. R. Reddy 한국고분자학회 2009 Macromolecular Research Vol.17 No.12

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>

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>

Copolymerization of N-Vinyl Pyrrolidone with Functionalized Vinyl Monomers: Synthesis, Characterization and Reactivity Relationships

Vijaykumar, S.,Prasannkumar, S.,Sherigara, B.S.,Shelke, N.B.,Aminabhavi, Tejraj M.,Reddy, B.S.R. The Polymer Society of Korea 2009 Macromolecular Research Vol.17 No.12

Copolymers of N-vinylpyrrolidone (NVP) comonomer with styrene (St), hydroxypropyl methacrylate (HPMA) and carboxyphenyl maleimide (CPMI) were synthesized by free radical polymerization using 2,2'-azobisisobutyronitrile (AIBN) initiator in 1,4-dioxane solvent. The copolymers formed were characterized by FTIR, $^1H$ NMR and $^{13}C$ NMR techniques and their thermal properties were studied by DSC and TGA. Copolymer composition was determined by $^1H$ NMR and/or by elemental analysis and monomer reactivity ratios (MRR) were estimated by the linear methods of Kelen-Tudos (K-T) and extended Kelen-Tudos (EK-T) and the non-linear approach. Copolymers of St and HPMA with NVP formed blocks of one of the monomer units, whereas alternating copolymers were obtained in CPMI-NVP, depending upon the side chain substitution. The MRR values are discussed in terms of monomer structural properties such as electronegativity and electron delocalization. The sequence distribution of monomers in the copolymers was studied by statistical method based on the average reactivity ratios obtained by EK-T method.

Electrical and mechanical properties of diluted magnetic semiconductor Zn_1-xMn_xS nanocrystalline films

Sreekantha Reddy, D.,Kang, B.,Yu, S.C.,Dwarakanadha Reddy, Y.,Sharma, S.K.,Gunasekhar, K.R.,Rao, K.N.,Sreedhara Reddy, P. Elsevier 2009 Current Applied Physics Vol.9 No.2

Nanostructured Zn<SUB>1-x</SUB>Mn<SUB>x</SUB>S films (0=<x=<0.25) were deposited on glass substrates by simple resistive thermal evaporation technique. All the films were deposited at 300K in a vacuum of 2x10<SUP>-6</SUP>m bar. All the films temperature dependence of resistivity revealed semiconducting behaviour of the samples. Hot probe test revealed that all the samples exhibited n-type conductivity. The nanohardness of the films ranges from 4.7 to 9.9GPa, Young's modulus value ranging 69.7-94.2GPa.

Hydrothermal synthesis of wurtzite Zn_1-xNi_xS mesoporous nanospheres: With blue-green emissions and ferromagnetic Curie point above room temperature

Amaranatha Reddy, D.,Kim, D.H.,Rhee, S.J.,Jung, C.U.,Lee, B.W.,Liu, C. Elsevier Sequoia 2014 JOURNAL OF ALLOYS AND COMPOUNDS Vol.588 No.-

Wurtzite Zn<SUB>1-x</SUB>Ni<SUB>x</SUB>S (x=0.00, 0.01, 0.02, 0.03, 0.04 and 0.05) mesoporous nanospheres were successfully synthesized via a versatile hydrothermal method with the assistance of ethylenediamine (EN). The as synthesized nanospheres were uniform, mono-dispersed with a spherical shape. Microstructure investigations revealed that these nanospheres were mesoporous clusters of Zn<SUB>1-x</SUB>Ni<SUB>x</SUB>S nanoparticles with the size around 5nm. X-ray Diffraction, X-ray photoelectron spectroscopy, and Energy-dispersive X-ray spectroscopy studies confirmed that the Ni ions substituted into ZnS host lattice without altering the crystal structure. The Fourier-transform infrared spectra confirmed the coupling between the EN molecules and ZnS. The absorption edge in the diffuse reflection spectra shifted towards lower wavelength with increasing Ni concentration, indicating an expansion in the band gap energy that is estimated to be in the range of 3.53-3.60eV. The photoluminescence spectra of the doped and un-doped samples contained a broad emission band covering the range of 350-650nm. Room temperature magnetization studies indicated that the undoped ZnS nanospheres yielded only diamagnetism, whereas the doped samples exhibited ferromagnetism that can be attributed to the Ni<SUP>2+</SUP> dopants. The temperature dependence of magnetization revealed that the Zn<SUB>1-x</SUB>Ni<SUB>x</SUB>S nanospheres have Curie point above room temperature. The intrinsic ferromagnetism and ferromagnetic Curie point above room temperature promise a great deal of potential applications in spintronic devices for Zn<SUB>1-x</SUB>Ni<SUB>x</SUB>S nanospheres.

Performance of Newly Evolved Bivoltine Silkworm Hybrids of Bombyx mori with Reference to Hybrid Vigour

Reddy, N.Mal,Basavaraja, H.K.,Kumar, N.Suresh,Joge, P.G.,Kalpana, G.V.,Dandin, S.B. Korean Society of Sericultural Science 2003 International Journal of Industrial Entomology Vol.7 No.1

In the present study, hybrid vigour in terms of heterosis and over dominance of newly evolved bivoltine hybrids and their reciprocals raised from the promising newly evolved bivoltine breeds were calculated for the important parameters like pupation, cocoon yield, cocoon weight, shell weight, shell ratio, raw silk percentage, filament length and neatness. Through there was no significant difference among the hybrids for the characters pupation, cocoon yield and cocoon weight, the magnitude of heterosis and over dominance were varied significantly for these characters. However, significant differences were observed between new hybrids and control hybrid for the characters like cocoon shell weight, cocoon shell ratio, filament length and raw silk percentage. The results indicate that majority of new hybrids have shown higher heterosis and over dominance than control hybrid. The data also indicate that highest mean heterosis of all new hybrids was recorded for cocoon yield followed by filament length. Whereas highest mean over dominance was recorded for cocoon yield followed by cocoon weight. Negative mean heterosis and over dominance were recorded for the trait cocoon shell ratio. Based on the results, the importance of three hybrids viz., CSR2 ${\times}$ CSR4, CSR2 ${\times}$ CSR5 and CSR3 ${\times}$ CSR6 and their reciprocals (CSR4 ${\times}$ CSR2, CSR5 ${\times}$ CSR2 and CSR6 ${\times}$ CSR3) which exhibited significant heterosis and over dominance, for commercial exploitation was discussed.

X-ray / gamma ray radiation shielding properties of a-Bi 2 O 3 synthesized by low temperature solution combustion method

B. Chinnappa Reddy,H.C. Manjunatha,Y.S. Vidya,K.N. Sridhar,U. Mahaboob Pasha,L. Seenappa,B. Sadashivamurthy,N. Dhananjaya,K.V. Sathish,P.S. Damodara Gupta 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.3

In the present communication, pure and stable a-Bismuth Oxide (Bi2O3) nanoparticles (NPs) weresynthesized by low temperature solution combustion method using urea as a fuel and calcined at 500oC. The synthesized sample was characterized by using powder X-ray Diffraction (PXRD), Scanning ElectronMicroscopy (SEM), Energy dispersive X-ray analysis (EDAX), Transmission Electron Microscopy (TEM),Fourier Transform Infrared Spectroscopy (FTIR) and UVeVisible absorption spectroscopy. The PXRDpattern confirms the formation of mono-clinic, stable and low temperature phase a-Bi2O3. The directoptical energy band gap was estimated by usingWood and Tauc's relation which was found to be 2.81 eV. The characterized sample was studied for X-ray/gamma ray shielding properties in the energy range0.081e1.332 MeV using NaI (Tl) detector and multi channel analyzer (MCA). The measured shieldingparameters agrees well with the theory, whereas, slight deviation up to 20% is observed below 356 keV. This deviation is mainly due to the influence of atomic size of the target medium. Furthermore an accuratetheory is necessary to explain the interaction of X-ray/gamma ray with the NPs.The present workopens new window to use this facile, economical, efficient, low temperature method to synthesizenanomaterials for X-ray/gamma ray shielding purpose

Terbium-doped ZnS quantum dots: Structural, morphological, optical, photoluminescence, and photocatalytic properties

Poornaprakash, B.,Chalapathi, U.,Suh, Youngsuk,Vattikuti, S.V. Prabhakar,Reddy, M. Siva Pratap,Park, Si-Hyun Elsevier 2018 CERAMICS INTERNATIONAL Vol.44 No.10

<P><B>Abstract</B></P> <P>Terbium (0, 2, and 4 at%)-doped ZnS quantum dots (QDs) were synthesized via a solvothermal method. The crystal structures of the synthesized QDs were determined to be zinc blend by X-ray powder diffraction (XRD) and Raman analyses. Transmission electron microscopy (TEM) studies revealed that particles with a mean size of 2–4 nm were formed. An X-ray photo electron spectroscopy (XPS) examination disclosed the existence of terbium with a trivalent state in the ZnS host lattice. The absorption bands of all QDs were located around 325 nm (3.81 eV) and were higher than that of the bulk ZnS band gap (3.67 eV), consistent with the quantum confinement effect. The photoluminescence spectra of the terbium-doped samples displayed five emission peaks at 467 nm (<SUP>5</SUP>D<SUB>4</SUB>→<SUP>7</SUP>F<SUB>3</SUB>), 491 nm (<SUP>5</SUP>D<SUB>4</SUB> → <SUP>7</SUP>F<SUB>6</SUB>), 460 nm (<SUP>5</SUP>D<SUB>4</SUB> – <SUP>7</SUP>F<SUB>5</SUB>), 484 nm (<SUP>5</SUP>D<SUB>4</SUB> – <SUP>7</SUP>F<SUB>4</SUB>), and 530 nm (<SUP>5</SUP>D<SUB>4</SUB> – <SUP>7</SUP>F<SUB>3</SUB>), respectively. The terbium-doped QDs exhibited a higher photocatalytic activity during the degradation of crystal violet dye under UV-light illumination compared to the undoped ZnS QDs. These interesting properties of terbium-doped ZnS QDs are potentially useful for both luminescent and photocatalysis applications.</P>