Biogenerated silica nanoparticles synthesized from sticky, red, and brown rice husk ashes by a chemical method

Sankar, S.,Sharma, S.K.,Kaur, N.,Lee, B.,Kim, D.Y.,Lee, S.,Jung, H. Ceramurgica ; Elsevier Science Ltd 2016 CERAMICS INTERNATIONAL Vol.42 No.4

An inexpensive chemical method was used to synthesize biogenic mesoporous silica (m-SiO<SUB>2</SUB>) from rice husk ash (RHA). A comparative study was carried out to produce silica nanoparticles (S-SiO<SUB>2</SUB>, R-SiO<SUB>2</SUB>, and B-SiO<SUB>2</SUB>) from three type of rice husk ashes (sticky, red, and brown). The microstructure of m-SiO<SUB>2</SUB> was dependent on the geographical provenance and the types of RHA. An analysis of the SEM and TEM micrographs reveals that the S-SiO<SUB>2</SUB> nanoparticles had a clustered spherical shape, while R-SiO<SUB>2</SUB> and B-SiO<SUB>2</SUB> nanoparticles were found to be purely spherical. The average crystallite size of S-SiO<SUB>2,</SUB> R-SiO<SUB>2</SUB> and B-SiO<SUB>2</SUB> nanoparticles evaluated from the TEM measurements were observed to be 50, 20 and 10nm, respectively. The XRD pattern of silica nanopowders had an absence of sharp peaks that confirmed the amorphous nature of the material. The Fourier transform infrared (FTIR) spectra of silica nanoparticles showed the symmetric Si-O and O-Si-O stretching bond vibrations at 462, 1088, and 1098cm<SUP>-1</SUP>. The surface area of S-SiO<SUB>2,</SUB> R-SiO<SUB>2</SUB> and B-SiO<SUB>2</SUB> nanopowders was measured to be 7.5513, 201.45, and 247.18m<SUP>2</SUP>g<SUP>-1</SUP>, respectively. The surface area of uniformly-distributed spherical nanoparticles of B-SiO<SUB>2</SUB> was observed the highest, which can be applied for the application of energy storage and drug delivery systems.

3D yolk-shell NiGa2S4 microspheres confined with nanosheets for high performance supercapacitors

Liu, S.,Kim, K.,Yun, J.,Kundu, A.,Sankar, K. V.,Patil, U.,Ray, C.,ChanJun, S. Royal Society of Chemistry 2017 Journal of Materials Chemistry A Vol.5 No.13

<P>Recent advances in the development of two-dimensional transition-metal chalcogenides (2D TMCs) have opened up new avenues for supercapacitor applications. However, they still suffer from limited specific capacitance and poor rate capability due to their poor interfacial properties and simple geometry. Here, we propose a facile strategy for the synthesis of yolk-shell NiGa2S4 microspheres comprising crumpled nanosheets supported on nickel foam. The robust structure not only highly facilitates the electron and charge transportation but also efficiently alleviates the volume expansion during redox reactions, contributing to excellent electrochemical behaviors in terms of specific capacitance and rate capability. Significantly, an asymmetric supercapacitor based on the prepared NiGa2S4 as the positive electrode and N, S-codoped graphene/Fe2O3 (N, S-G/Fe2O3) as the negative electrode delivers a high energy density of 43.6 W h kg(-1) at a power density of 961 W kg(-1) and retains an energy density of 22.2 W h kg(-1) even at 15 974 W kg(-1). These impressive results may provide a new perspective to develop high energy and power density storage systems for practical applications.</P>

Controllable sulfuration engineered NiO nanosheets with enhanced capacitance for high rate supercapacitors

Liu, S.,Lee, S.,Patil, U.,Ray, C.,Sankar, K. V.,Zhang, K.,Kundu, A.,kang, S.,Park, J.,ChanJun, S. Royal Society of Chemistry 2017 Journal of Materials Chemistry A Vol.5 No.9

<P>NiO has been intensively studied as a promising electrode material for supercapacitors because of its high theoretical specific capacitance, well-defined redox behavior, and good chemical compatibility with nickel foam. However, it still suffers from inferior rate capability and cycling stability because of the simple component and random structural integration. Herein, we report a tunable sulfuration process of NiO nanosheets constructed on porous nickel foam for supercapacitor applications. The resulting NiO/Ni3S2 with distinct structural features exhibits an ultra-high specific capacitance of 2153 F g(-1) at a current density of 1 A g (1), and the capacitance is retained at 1169 F g (1) even at a current density as high as 30 A g (1). An asymmetric supercapacitor device fabricated with NiO/Ni3S2 as the positive electrode and activated carbon as the negative electrode delivers high energy and power densities (52.9 W h kg(-1) at 1.6 kW kg(-1); 26.3 W h kg(-1) at 6.4 kW kg(-1)), and good cycling stability (a capacitance retention of 92.9% over 5000 cycles).</P>

Rapid sonochemical synthesis of spherical silica nanoparticles derived from brown rice husk

Sankar, S.,Kaur, Narinder,Lee, Sejoon,Kim, Deuk Young Elsevier 2018 CERAMICS INTERNATIONAL Vol.44 No.7

<P><B>Abstract</B></P> <P>The nanoparticles of silica (SiO<SUB>2</SUB>) were synthesized from brown rice husk <I>via</I> the sonochemical process, during which the sonication time was varied from 0 to 50 min so as to modulate the material properties of the nanoparticles. The synthesized SiO<SUB>2</SUB> nanoparticles were confirmed to have amorphous natures in their structural characteristics. The mean particle sizes of the nanoparticles were increased from 5 to 40 nm with increasing sonication time from 0 to 50 min, respectively. The SiO<SUB>2</SUB> nanoparticles synthesized with the sonication time of 50 min showed to possess the highest porosity among our samples. Accordingly, the sample exhibited a higher effective surface area of 271.22 m<SUP>2</SUP>g<SUP>−1</SUP>. In addition, the bandgap of the SiO<SUB>2</SUB> nanoparticles was decreased from 5.77 to 5.68 eV with increasing sonication time (<I>i.e.</I>, 0 → 50 min). The results suggest that the SiO<SUB>2</SUB> nanoparticles synthesized with an appropriate control of the sonication time (<I>e.g.</I>, 50 min) hold promise for future nano-ecosystem applications such as nano-biosensors and energy storage nano-devices.</P>

Ultrathin graphene nanosheets derived from rice husks for sustainable supercapacitor electrodes

Sankar, S.,Lee, H.,Jung, H.,Kim, A.,Ahmed, A.,Inamdar, A.,Kim, H.,Lee, S.,Im, H.,YoungKim, D. Royal Society of Chemistry 2017 New journal of chemistry Vol.41 No.22

Microstructure, structural, optical and piezoelectric properties of BiFeO₃ nanopowder synthesized from sol-gel

Sankar Ganesh, R.,Sharma, S.K.,Sankar, S.,Divyapriya, B.,Durgadevi, E.,Raji, P.,Ponnusamy, S.,Muthamizhchelvan, C.,Hayakawa, Y.,Kim, D.Y. ELSEVIER 2017 Current Applied Physics Vol.17 No.3

<P>Nanocrystalline BiFeO3 (BFO) powder was synthesized by sol-gel method and subsequent annealed at 100-500 degrees C. The microstructural analysis of BFO nanopowder confirmed the perovskite like structure of spherical nanoparticles annealed at 500 degrees C. The Raman spectrum of BFO nanoparticles showed the rhombohedrally structure with the space group of R3c. The XPS spectrum of BFO nanopowder showed the peaks of Bi, Fe, and O at the binding energy of 158.8, 711.75 and 529.2 eV, respectively. The piezoelectric properties of BFO nanoparticles were evaluated by making the sandwiched structure of graphene/BiFeO3-PDMS/graphene. The fabricated piezoelectric device demonstrated an output voltage of 0.4 V by applying the normal pressure from human finger on the device. (C) 2016 Elsevier B.V. All rights reserved.</P>

Fabrication of the flexible nanogenerator from BTO nanopowders on graphene coated PMMA substrates by sol-gel method

Sankar Ganesh, R.,Sharma, Sanjeev K.,Abinnas, N.,Durgadevi, E.,Raji, P.,Ponnusamy, S.,Muthamizhchelvan, C.,Hayakawa, Y.,Kim, Deuk Young Elsevier Sequoia S.A 2017 Materials chemistry and physics Vol.192 No.-

<P><B>Abstract</B></P> <P>Nanostructured bismuth titanate (Bi<SUB>4</SUB>Ti<SUB>3</SUB>O<SUB>12</SUB>) or BTO powders were synthesized by the combustion method. The crystalline phase of BTO nanopowders was evaluated from X-ray diffraction (XRD) and further confirmed by selected area electron diffraction (SAED) pattern. The SEM and TEM micrographic images clearly showed the nanosheets like morphology of BTO nanopowder. The EDS spectrum of BTO nanopowder showed the elemental peaks of O, Bi and Ti at 0.53 keV, 2.41 keV and 4.49 keV, respectively. FTIR band peaks were observed at 815 and 595 cm<SUP>−1</SUP> corresponding to the stretching vibrations of BiO and TiO. The red shift in optical absorption of BTO was observed and the bandgap decreased from 3.18 to 3.08 eV as the calcined temperature increased from 600 to 800 °C. The sandwich structure, called the nanogenerator, Graphene/BTO-PDMS/Graphene (G/BTO/G), was fabricated on graphene coated polymethyl methacrylate (PMMA) substrates, which produced a peak voltage (10 mV) by applying the pressure from human's finger. The switching mechanism of BTO nanosheets was observed to be dependent on the polarity and intrinsic dipole formation.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Bi<SUB>4</SUB>Ti<SUB>3</SUB>O<SUB>12</SUB> (BTO) nanosheets synthesized from a simple combustion method. </LI> <LI> SEM & TEM images confirmed the nanosheets structure with a hexagonal shape. </LI> <LI> XRD and SAED pattern of BTO nanosheets confirmed the orthorhombic crystal structure. </LI> <LI> Flexible G/BTO/G nanogenerator fabricated by sol-gel method. </LI> <LI> Peak voltage was observed to be 10 mV by applying pressure from human's finger. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Studies on the Manifestation of Hybrid vigour and Combining Ability in Polyvoltine x Bivoltine (cross breed) Hybrids of Mulberry Silkworm Bombyx mori L.

( S. V. Seshagiri ),( S. Sankar Naik ),( J. Seetharamulu ),( A. K. Goel ),( P. J. Raju ) 한국잠사학회 2012 International Journal of Industrial Entomology Vol.24 No.1

To meet the local requirement i.e. the tropical stress of Andhra Pradesh and marginal farmers, twenty four new hybrid combinations were tested in Line x Tester method involving eight newly developed polyvoltine oval lines viz., MSO1, MSO2, MSO3, MSO4, MSO5, MSO6, MSO7 and MSO8 and three bivoltine silkworm breeds viz., APS12, APS45 and APS8 as testers. These hybrids were reared to evaluate their performance. Data for eight economically important metric traits viz., fecundity, cocoon yield per 10,000 larvae by number, cocoon yield per 10,000 larvae by weight, survival rate, cocoon weight, cocoon shell weight, cocoon shell ratio and filament length was recorded. General combining ability (gca), specific combining ability (sca) and heterosis were analyzed. Further, the relative merit of the hybrids for all the traits under study was also assessed adopting Evaluation Index method. Based on combining ability effects, heterosis and evaluation index, five hybrid combinations viz., MSO3 x APS45, MSO1 x APS12, MSO7 x APS8, MSO2 x APS45 and MSO1 x APS45 were selected for further evaluation in different seasons.

Binder-free cobalt phosphate one-dimensional nanograsses as ultrahigh-performance cathode material for hybrid supercapacitor applications

Sankar, K. Vijaya,Lee, S.C.,Seo, Y.,Ray, C.,Liu, S.,Kundu, A.,Jun, S.C. Elsevier Sequoia 2018 Journal of Power Sources Vol. No.

<P><B>Abstract</B></P> <P>One-dimensional (1D) nanostructure exhibits excellent electrochemical performance because of their unique physico-chemical properties like fast electron transfer, good rate capability, and cyclic stability. In the present study, Co<SUB>3</SUB>(PO<SUB>4</SUB>)<SUB>2</SUB> 1D nanograsses are grown on Ni foam using a simple and eco-friendly hydrothermal technique with different reaction times. The open space with uniform nanograsses displays a high areal capacitance, rate capability, energy density, and cyclic stability due to the nanostructure enhancing fast ion and material interactions. Ex-situ microscope images confirm the dependence of structural stability on the reaction time, and the nanograsses promoted ion interaction through material. Further, the reproducibility of the electrochemical performance confirms the binder-free Co<SUB>3</SUB>(PO<SUB>4</SUB>)<SUB>2</SUB> 1D nanograsses to be a suitable high-performance cathode material for application to hybrid supercapacitor. Finally, the assembled hybrid supercapacitor exhibits a high energy density (26.66 Wh kg<SUP>−1</SUP> at 750 W kg<SUP>−1</SUP>) and longer lifetimes (80% retained capacitance after 6000 cycles). Our results suggests that the Co<SUB>3</SUB>(PO<SUB>4</SUB>)<SUB>2</SUB> 1D nanograss design have a great promise for application to hybrid supercapacitor.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Binder-free cobalt phosphate cathode for hybrid supercapacitor. </LI> <LI> Stable structure and good electrochemical interaction confirmed via morphology. </LI> <LI> Uniform and direct growth enhances the electrochemical performance. </LI> <LI> The OH<SUP>−</SUP> ions more favor for large energy storage than NO<SUB>3</SUB> <SUP>−</SUP> ions. </LI> <LI> Ex-situ analysis confirms the influence of morphology on cyclic stability. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

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

Sankar, S.,Sharma, Sanjeev K.,An, Namhyun,Lee, Hwauk,Kim, Deuk Young,Im, Young Bin,Cho, Yung Duk,Ganesh, R. Sankar,Ponnusamy, S.,Raji, P.,Purohit, L.P. Elsevier 2016 OPTIK -STUTTGART- Vol.127 No.22

<P><B>Abstract</B></P> <P>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 35.44nm to 30.5nm and the bandgap increased from 3.79eV to 3.95eV as the Mn concentration increased from 0wt.% to 4wt.%. The photocatalytic properties of NiO:Mn nanopowders were measured for the lowest and highest Mn dopant concentrations (Mn: 0 & 4wt.%) by using the methylene blue dye under UV illumination. The NiO:Mn (Mn: 4wt.%) nanoparticles showed the highest photocatalytic activity due to the highest activation sites. Therefore, it is revealed that the Mn: 4wt.% nanoparticles are observed to be more suitable for the photocatalytic activity of methylene blue dye degradation.</P>