Abstract
The variation of oxygen functional groups (OFGs) is extremely complicated during the thermal treatment of graphene oxide (GO). Selectively improving the content of electrochemically active OFGs through multi-step thermal treatment is a promising strategy to enhance the charge storage capability of graphene-based supercapacitor electrodes. In this work, a two-step thermal treatment method was used to produce reduced graphene oxide (RGO) with selectively increasing the content of electrochemically active quinone-type carbonyl groups (C˭O). The first step is thermal reduction at 500 °C in Ar atmosphere, during which GO is exfoliated into separated sheets with porous structure and larger surface area; the second step is air oxidation at 400 °C, which facilitates the selective formation of quinone-type C˭O groups and enhances the mesoporous fraction. Due to the pseudocapacitive behavior of quinone-type C˭O groups and low ion diffusion resistance, the electrode prepared by RGO exhibits a high specific capacitance of 303 F g−1 at 0.2 A g−1 with excellent rate capability (202 F g−1 at 10 A g−1) and notable cycling performance (~ 116% capacitance retention after 1500 cycling at 1 A g−1). The present work proposed a facile and environmentally friendly two-step thermal treatment strategy in effectively controlling the surface property and microstructure of graphene materials, which has significant implications for mass producing graphene materials for supercapacitor electrodes.
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More From: Colloids and Surfaces A: Physicochemical and Engineering Aspects
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