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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>
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>
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>
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>
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>
S. Sankar Ganesh,A. Jegan 한양대학교 청정에너지연구소 2023 Journal of Ceramic Processing Research Vol.24 No.3
In this research work, Ni- nano SiC coating was pulse electrodeposited on Al 7075 substrate in a watt’s bath. A 3-level, 3-factorcentral composite design (CCD) of experiments were carried out to assess the influence of pulse plating parameters, i.e.,Current Density (A/cm2), Duty Cycle (%), Frequency (Hz) on the microhardness of Ni-SiC coating. A regression model isdeveloped to predict the microhardness of the developed coating using design expert software and optimal parameters forachieving maximum microhardness were found out. The morphology of the nano SiC coating was investigated using FESEMcoupled with EDAX, and X-ray diffractometer. Corrosion studies were carried out using Potentiometric polarization andElectrochemical Impedance tests, and the corrosion results show that corrosion potential for the aluminium alloy is -0.92 Vand for the Ni- nano SiC coating it increases to -0.65 V. Tafel and Nyquist plots reveal the improved corrosion characteristicsof the pulse plated Ni-SiC coating. Significant improvement in the microhardness of the coating is achieved with a maximumhardness of 329.6 HV. Results show that about 3 time’s enhancement in the microhardness obtained with the Ni-SiC nanocomposite coating, when compared to the Al7075 substrate.
Sankar, S.,Inamdar, Akbar I.,Im, Hyunsik,Lee, Sejoon,Kim, Deuk Young Elsevier 2018 CERAMICS INTERNATIONAL Vol.44 No.14
<P><B>Abstract</B></P> <P>Spherical MnO<SUB>2</SUB> nanoparticles were synthesized at room temperature <I>via</I> template-free sonochemical reduction of potassium permanganate using a reducing agent of polyethylene glycol under two different time durations (<I>i.e.</I>, 15 min (M1) and 30 min (M2)). The M2 sample exhibited the α-phase of the tetragonal MnO<SUB>2</SUB> structure, whereas the M1 sample showed the δ-MnO<SUB>2</SUB> phase. For microstructural analyses, the M2 sample revealed a spherical structure of the nanoparticles with an average grain size of 20–30 nm. When using spherical MnO<SUB>2</SUB> nanoparticles (<I>i.e.</I>, M2) as an electrode material for the supercapacitor device, the maximum specific capacitance of 136 F/g was observed at the current density of 0.5 A/g. The device displayed an excellent cyclic stability of 72% after 5000 charge/discharge cycles, and showed a high energy density up to 38.3 Wh/kg. These results suggest that the sonochemically-synthesized spherical MnO<SUB>2</SUB> nanoparticles could be used as a suitable electrode material for high-energy electrochemical supercapacitors.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>