▎ 摘　　要

Vertically oriented graphene nanosheets are promising electrode materials for electrochemical double-layer capacitors. The external surface area of the nanosheets allows for extremely fast response times compared to porous carbon materials currently used. Furthermore, the high edge density increases the charge storage ability of the material. In this paper Ar+ ions were used to create a larger density of surface defects, which were then characterized by X-ray photoelectron spectroscopy and near-edge X-ray absorption fine structure spectroscopy. The results indicate a change in the density of states near the Fermi level with increased defect density, which suggests a corresponding increase in electrochemical capacitance capability. Published by Elsevier Ltd.