The role of holes in improving the performance of nitrogen-doped holey graphene as an active electrode material for supercapacitor and oxygen reduction reaction

Abstract

Nitrogen doped holey graphene (NHG), with in-plane holes in its sheet plate, has been synthesized in this work through the potassium hydroxide (KOH) etching and ball milling of nitrogen doped graphene (NG). It shows that the KOH etching and ball milling does not distinctly alter the elemental composition and the relative percentages of functional groups in NG, but produce holes in its in-plane sheet plate. The obtained NHG can then be used as an active electrode material for supercapacitors and as an active electrocatalyst for oxygen reduction reaction, and exhibits significantly higher electrochemical performance than the corresponding NG. Its improved electrochemical performance could be attributed to its specific holey structure in the sheet plate and porous structure in its randomly stacked solid, which provide it with more active edge atoms, better accessibility to electrolyte, larger accommodation space for ions, faster electrolyte diffusion and movement and so on.