• SAYANTAN SINHA

Articles written in Bulletin of Materials Science

• Silver-decorated reduced graphene oxide nanocomposite for supercapacitor electrode application

Silver-decorated reduced graphene oxide (Ag@rGO) nanocomposite was synthesized via a facile chemical reduction method, and its morphology, functional groups, structure, optical and electrical characteristics were investigated.Large distributions of spherical Ag nanoparticles with particle size ranging from 108 to 126 nm anchored into rGO sheets were observed. The energy dispersive X-ray confirms the presence of carbon, oxygen and silver elements in the Ag@rGO nanocomposite. Fourier-transform infrared spectrum exhibited stretching vibrations due to C=O, C–H$_2$, C–O,C=C, O–H and Ag–O bonds in Ag@rGO nanocomposite. X-ray diffraction results of Ag@rGO nanocomposite confirmthe formation of rGO and metallic Ag nanoparticles exhibiting FCC structure. The bandgap and ID/IG values of Ag@rGO nanocomposite were obtained as 2.76 and 1.49 eV respectively. Moreover, the study of electrochemical properties ofAg@rGO nanocomposite was carried out, where the maximum specific capacitance of 717.3 and 433.05 F g$^{-1}$ was achieved at 5 mV s$^{-1}$ scan rate and 1 A g$^{-1}$ current density. Moreover, the impedance spectroscopy study exhibited thecharge transfer resistance (R$_{CT}$) value as 6.98 and 71.29${\Omega}$ from the Nyquist and Bode plots. I–V characteristics curveshows that the addition of Ag into rGO increases its electrical conductivity. Thus, the results of Ag@rGO nanocompositecan be suitable for supercapacitor application.

• Optical, electrochemical and corrosion resistance properties of iron oxide/reduced graphene oxide/polyvinylpyrrolidone nanocomposite as supercapacitor electrode material

Iron oxide (Fe$_3$O$_4$)/reduced graphene oxide (rGO)/polyvinylpyrrolidone (PVP) nanocomposite films with varying iron weight percentages were prepared by electrospinning spray method on glass, aluminium foil and Si (100)substrate. The size of Fe$_3$O$_4$/rGO/PVP composite particles varied between 0.75 and 1.35 ${\mu}$m on the surface of the graphene sheet. The diffraction peaks at 36.77°, 47.06°, 52.98° and 61.34° confirmed the plane (311), (400), (422) and(440) of the Fe$_3$O$_4$ crystal lattice, respectively. The broad peaks around 26.6° and 43.47°correspond to the planes (002) and (102) for the rGO sheet in the Fe$_3$O$_4$/rGO/PVP nanocomposite films. The defect parameter, $I_D$/$I_G$ ratio varied from 0.17 to 0.34 with 15 and 25wt% Fe$_3$O$_4$ content, respectively, indicates the decreasing of defects in the Fe$_3$O$_4$/rGO/PVP network. The minimum value of $E_{corr}$ and $I_{corr}$ are 0.18 V and 4.76 ${\mu}$A, respectively.

• Structural, optical and electrochemical properties of banana, mango leaves and potato extracts reduced graphene oxide

Green synthesis of reduced graphene oxide (rGO) was done using three different plant extracts, such as banana, mango leaves and potato, as the reducing agent. The field-emission scanning electron spectroscopy revealed the formation of thin layers in the morphology of rGO reduced with the green extracts. The X-ray diffraction patterns reveal that the peak for GO (001) appeared at 2${\theta}$ = 11.01°and in rGO broad peak appeared for the (002) plane at ${\sim}$21°–26°. TheFourier transform infrared spectroscopy graphs showed the peaks for C=C at ${\sim}$1571 cm$^{-1}$, which confirmed the formation of the graphene backbone structure. Raman analysis showed the characteristic G band for the sp$^2$ carbon structureof rGO. The cyclic voltammetry study revealed that the rGO-b exhibits the most significant value of specific capacitance of 176 F g$^{–1}$ at a 5 mV s$^{–1}$ scan rate.

• # Bulletin of Materials Science

Volume 46, 2023
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Continuous Article Publishing mode

• # Dr Shanti Swarup Bhatnagar for Science and Technology

Posted on October 12, 2020

Prof. Subi Jacob George — Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bengaluru
Chemical Sciences 2020