Fabricating pyridinic N-B sites in porous carbon as efficient metal-free electrocatalyst in conversion CO2 into CH4

Abstract

Electrochemical reduction of CO2 (CO2RR) to value-added chemicals is an attractive strategy for greenhouse gas mitigation and carbon recycle. Carbon material is one of most promising electrocatalysts but its product selectivity is limited by few modulating approaches for active sites. Herein, the predominant pyridinic N-B sites (accounting for 80% to all N species) are fabricated in hierarchically porous structure of graphene nanoribbons/amorphous carbon. The graphene nanoribbons and porous structure can accelerate electron and ion/gas transport during CO2RR, respectively. This carbon electrocatalyst exhibits excellent selectivity toward CO2 reduction to CH4 with the faradaic efficiency of 68% at −0.50 V vs. RHE. As demonstrated by density functional theory, a proper adsorbed energy of *CO and *CH2O are generated on the pyridinic N-B site resulting into high CH4 selectivity. Therefore, this study provides a novel method to modulate active sites of carbon-based electrocatalyst to obtain high CH4 selectivity.