Mechanistic insight into electroreduction of carbon dioxide on FeNx (x = 0–4) embedded graphene

Abstract

Searching for non-precious, active and stable catalysts for CO₂ electrochemical reduction (CO₂ER) has attracted extensive attention, while the high overpotential and low efficiency hinder their widespread commercial applications on a large scale. In this work, density functional theory (DFT) calculations were conducted on the CO₂ER process over FeN_x embedded graphene (i.e., FeN_x–gra, x = 0–4). The results reveal that the Fe atom strongly interacts with the unsaturated N atoms of the substrate and acts as the active site. Due to the small limiting potential of −0.78 V and the activation barrier (1.56 eV), FeN₃–gra exhibits the highest catalytic activity towards CO₂ reduction. The products of CO₂ER catalyzed by FeN₃–gra are CH₄ and CH₃OH, in which CO* → HCO* is the potential-determining step. It is expected that FeN₃–gra would be a promising catalyst for CO₂ER.