Oxygen Species on Nitrogen-Doped Carbon Nanosheets as Efficient Active Sites for Multiple Electrocatalysis.

Designing and synthesizing nanomaterials with high coverages of active sites is one of the most-pivotal factors in the construction of state-of-the-art electrocatalysts with high performance. Herein, we proposed a facile in situ templated method for the fabrication of oxygen-species-modified nitrogen-doped carbon nanosheets (O-N-CNs). The epoxy oxygen and ketene oxygen combined with graphitic-nitrogen defects in O-N-CNs gave more active sites for the oxygen-reduction reaction (ORR) and the oxygen-evolution reaction (OER), as proven via theoretical and experimental results, while the carbonyl-oxygen and epoxy-oxygen species showed more efficient electrocatalytic activity for the hydrogen evolution reaction (HER). Hence, the O-N-CNs showed highly active electrocatalytic performance toward ORR, OER, and HER. More importantly, the superior multifunctional electrocatalytic activity of O-N-CNs allowed their use in the construction of Zn-air batteries to power the corresponding water-splitting cells. This work can offer an understanding of underlying mechanisms of oxygen species on N-doped carbon materials toward multiple electrocatalysis and facilitate the engineering of electrocatalysts for energy-storage and -conversion devices.