Enhanced electrochemical performance of graphene aerogels by using combined reducing agents based on mild chemical reduction method

In recent years, 3D assemblies of graphene are developed as promising materials in various applications, such as energy storage devices. In this paper, we have reported a method for the synthesis of Graphene Aerogel (GA) utilizing a novel reducing system to achieve high electrochemical properties. GAs were obtained via chemical reduction of Graphene Oxide (GO) using a combination of L-Ascorbic Acid (L-AA) and sodium bisulfite (NaHSO3) as the combined reduction media (GASL). However, L-AA exhibited a high level of reduction resulting in a micro/mesoporous structure, but it is incapable of de-epoxidation with high efficiency. Besides, NaHSO3 enhanced the de-epoxidation step, decreased the shrinkage of the structure, and also increased the size of the pores. The synergistic effect of the combined reducing system led to the proper level of reduction with meso/macroporous structure and lowered shrinkage, which improved the electrochemical performance. The N-2 adsorption analysis with BET formula estimated the specific surface area and the pore volume of 135 m(2)g(-1) and 2.9 cm(3)g(-1), respectively. Moreover, FT-IR spectroscopy admitted a high level of reduction for GASL in comparison with single reducing agent samples. The GASL exhibited a high specific capacitance (165 Fg(-1) at 1 Ag-1), excellent cycling stability (91% capacitance retention after 1000 cycles) and an adequate capacitive performance (91% capacitance retention by the increase in current density from 1 to 5 Ag-1) with low internal resistance (about 0.005 V). The desired results are due to the high level of reduction and the meso/macroporous structure.