Porous reduced graphene oxides derived by selective removal and formation of oxygen functional groups and their electrochemical capacitances

In this study, reduced graphene oxides (rGOs) with a porous structure were synthesized through a facile sequential low-temperature treatment at 150 and 250 degrees C in air and nitrogen atmosphere, respectively, without toxic chemicals. For the first treatment under oxygen-rich conditions, competitive oxidation and reduction reactions between various kinds of oxygen functional groups were observed, leading to the formation of preferential pore-forming groups such as carboxyl. Weakly bound groups on the GO surface (such as hydroxyl and carboxyl groups) were removed in the second step, leading to the formation of pores and improving electrical conductivity. The rGO suitable for use as an electrode material had a surface area of 636.6 m(2)/g and a capacitance of 191.3 F/g. Therefore, we believe that this mild treatment could be a potentially cost-effective, efficient, and environmentally friendly strategy to synthesize electrode materials. (C) 2020 Elsevier Ltd. All rights reserved.