Synergistic effects of heteroatom-decorated MXene catalysts for CO reduction reactions

Abstract

In this study, using the density functional theory calculations, we present a strategy to improve the activity and selectivity of electrocatalytic CO reduction reactions (CORRs) towards CH₄ production occurring on single transition metal (TM) atoms embedded in a defective MXene Mo_2−xTiC₂O_y with one oxygen vacancy. Owing to the unique geometric and electronic structures, the exposed TM–Mo–Mo triangle can serve as an active site, and the surrounding oxygen atoms can break the scaling relationships between the CORR intermediates via the steric hindrance. The synergistic effects result in an excellent catalytic performance for CORRs. Based on the extensive investigation of series of candidates, W-decorated MXene was identified as the most promising CORR electrocatalyst, with a high selective activity towards the CH₄ production and strong suppression of competing hydrogen evolution reactions (HERs). The adsorption free energy of *COH [ΔG_ads (*COH)] is proposed as a descriptor to establish a relationship with the catalytic activity. Our rational design principles and rapid screening methods may shed light on the development of other highly efficient CORR electrocatalysts, as well as the other electrochemical systems.