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

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. [Display omitted] Nitrogen doped holey graphene, synthesized through the KOH etching and ball milling of nitrogen doped graphene, has been reported to exhibit significantly high electrochemical performance as an active electrode material for supercapacitors and as an efficient metal-free catalyst for oxygen reduction reaction. •A simple KOH etching and ball milling method is been used to synthesize NHG.•NHG exhibits high electrochemical performance for supercapacitors.•NHG exhibits high electrochemical performance for oxygen reduction reaction.•The holes facilitate the formation of the NHG solid with a porous structure.•The holes play an important role in improving the electrochemical performance of NHG.