Active Edge-Site-Rich Carbon Nanocatalysts with Enhanced Electron Transfer for Efficient Electrochemical Hydrogen...

A highly efficient, metal-free carbon nanocatalyst is presented that possesses abundant active, oxygenated graphitic edge sites. The edge site-rich nanocarbon catalyst exhibits about 28 times higher activity for H₂ O₂ production than a basal plane-rich carbon nanotube with a H₂ O₂ selectivity over 90 %. The oxidative treatment further promotes the H₂ O₂ generation activity to reach close to the thermodynamic limit. The optimized nanocarbon catalyst shows a very high H₂ O₂ production activity, surpassing previously reported catalysts in alkaline media. Moreover, it can stably produce H₂ O₂ for 16 h with Faradaic efficiency reaching 99 % and accumulated H₂ O₂ concentration of 24±2 mm. Importantly, we find that the heterogeneous electron transfer kinetics of the carbon-based catalyst is closely related to the electrocatalytic activity, suggesting that first outer-sphere electron transfer to O₂ is an important step governing the H₂ O₂ production rate.