Heteroatom-doped nanocarbons are considered promising metal-free catalysts for both oxygen reduction and oxygen evolution reactions. However, the origin of electrocatalytic activity in such materials is normally based on a trial and error approach and therefore remains unclear. Herein, a bifunctional graphene catalyst containing nitrogen heteroatom dopants and edge-rich defects as active sites was proposed to probe the underlying mechanism behind the electrocatalytic activity. This ubiquitous graphene material with abundant topological defects is achieved <i>via</i> the carbonization of natural gelatinized sticky rice on hard templates and afford superb bifunctional oxygen electrocatalysis performance. The first-principle simulations reveal the critical importance of edge and topological defects in the activity originate of metal-free nanocarbons for oxygen electrocatalysis. A nitrogen-free configuration with adjacent pentagon and heptagon carbon rings exhibits the lowest overpotential with 0.14 V for ORR and 0.21 V for OER. The synthetic strategy and insights on the ORR and OER mechanism facilitate the development of advanced metal-free carbocatalysts for a wide range of electrocatalytic applications.

Topological defects in nanocarbons for oxygen electrocatalysis

254th National Meeting (2017)

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