Efficient reduction of graphene oxide using Tin-powder and its electrochemical performances for use as an energy storage electrode material

A green and facile approach for the reduction of graphene oxide (GO) to graphene has been reported using Tin (Sn) powder and dilute hydrochloric acid. Reduction has been performed by varying time from 0.5 to 3 h at room temperature (RT) and 50 °C to determine the best conditions for high quality crystalline graphene. The as-prepared Sn-reduced GO (SR-GO) has been characterized by Fourier transform infrared spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy and Transmission electron microscopy. The efficiency of the reduction increases with increasing reduction time at RT and at 50 °C as evidenced by the electrical conductivity study. However, the electrical conductivity of SR-GO obtained at RT is significantly greater than that of SR-GO obtained at 50 °C. This is attributed to the presence of unreacted Sn particles that increase the electrical conductivity of graphene sheets, as evidenced by XPS elemental analysis. The electrochemical performances of SR-GOs were analyzed by cyclic voltammetry, charge-discharge and electrochemical impedance spectroscopy analysis. A maximum specific capacitance of 152 F g^-1 at a current density of 1.5 A g^-1 was recorded for graphene prepared at 50 °C for 3 h. The retention in specific capacitance was 92% after 1500 charge-discharge cycles, indicating good electrochemical cyclic stability of SR-GO and its suitability as an energy storage electrode material.