Oxygen\nSpecies on Nitrogen-Doped Carbon Nanosheets\nas Efficient Active Sites for Multiple Electrocatalysis

Abstract

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