Impact of interfacial electron transfer on electrochemical CO₂ reduction on graphitic carbon nitride/doped graphene

Abstract

Effective electrocatalysts are required for the CO2 reduction reaction (CRR), while the factors that can impact their catalytic activity are yet to be discovered. In this article, graphitic carbon nitride (g-C3 N4 ) is used to investigate the feasibility of regulating its CRR catalytic performance by interfacial electron transfer. A series of g-C3 N4 /graphene with and without heteroatom doping (C3 N4 /XG, XG = BG, NG, OG, PG, G) is comprehensively evaluated for CRR through computational methods. Variable adsorption energetics and electronic structures are observed among different doping cases, demonstrating that a higher catalytic activity originates from more interfacial electron transfer. An activity trend is obtained to show the best catalytic performance of CRR to methane on C3 N4 /XG with an overpotential of 0.45 V (i.e., -0.28 V vs reverse hydrogen electrode [RHE]). Such a low overpotential has never been achieved on any previously reported metallic CRR electrocatalysts, therefore indicating the availability of C3 N4 /XG for CO2 reduction and the applicability of electron transfer modulation to improve CRR catalytic performance.