• PINKU KRISHNAN

      Articles written in Bulletin of Materials Science

    • Effect of electrolyte concentration on the electrochemical performance of RGO–KOH supercapacitor

      PINKU KRISHNAN V BIJU

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      The electrolyte used, plays a crucial role in the electrochemical performance of supercapacitors. It is known that the concentration of electrolyte is also a controlling parameter for a given active material where the performance will be optimum for a particular concentration. Herein, we report a study on the effect of electrolyte concentration on the electrochemical performance of reduced graphite oxide–potassium hydroxide supercapacitor. The supercapacitor achievesa maximum specific capacitance of 232 F g$^{-1}$ in 6 M KOH with energy and power density values of ${\sim}$21 Wh kg$^{-1}$ and ${\sim}$400 W kg$^{-1}$, respectively. The kinetics of charge storage reveals that the combination of surface phenomenon andintercalation process leads to maximum specific capacitance.

    • Reduced graphene oxide derived from urea-assisted solution combustion route and its electrochemical performance

      G PRADEEP KUMAR PINKU KRISHNAN M S ARSHA I N JAWAHAR V BIJU

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      Reduced graphene oxide (rGO) is synthesized from graphite oxide through urea-assisted solution combustion route. X-ray diffraction analysis reveals a decrease in the interplanar spacing ($d_{002}$) value from 8.14 to 3.44 Aº oncombustion due to reduction. Number of graphitic layers decreases from 58 to 9 on combustion indicating efficient exfoliation. Scanning electron micrographs reveal substantial reduction in the lateral dimension of graphitic planes fromgreater than ${\sim}$1${\mu}$m to less than ${\sim}$380 nm. Raman spectroscopy studies indicate an enhancement of defects in the rGO with an $I_D$/$I_G$ ratio of 1.19. Diminishing intensity of vibrational modes of different oxygen functional groups in the Fourier transform infrared spectrum and higher carbon to oxygen ratio of 12.13 from X-ray photoelectron spectroscopy indicate excellent reduction. N1s X-ray photoelectron spectrum confirms nitrogen doping. Electrical conductivity of rGO is 38 Sm$^{-1}$. The sample as an active material in a three-electrode configuration with 6 M KOH electrolyte exhibits a capacitance of 75.1 F g$^{-1}$ at a current density of 0.1 A g$^{-1}$, and 63% of it is retained even at a current density of 10 A g$^{-1}$. It also exhibits 103% of its initial capacitance after 1000 cycles.

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      Posted on October 12, 2020

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      Prof. Surajit Dhara — School of Physics, University of Hyderabad, Hyderabad
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      Posted on July 25, 2019

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