Electrochemical CO₂ Reduction Reaction on 3d Transition Metal Single-Atom Catalysts Supported on Graphdiyne: A DFT Study

Abstract

In the electrochemical CO2 reduction reaction (CO2RR), single atom catalysts (SACs) supported on carbon materials have exhibited high activity and selectivity. However, the carbon supports are mainly graphene and carbon nanotubes, which are composed of sp2-hybridized carbon. Graphdiyne with sp-hybridization has been investigated as a promising carbon material for various catalytic reactions. In this study, the effect of sp-hybridization on graphdiyne was investigated using density functional theoretical (DFT) calculations for the CO2RR reactivity of Mn, Fe, Co, Ni, Cu, and Zn SACs supported on graphdiyne (M–graphdiyne). Among them, Co–graphdiyne exhibits a high activity and selectivity for CH3OH product, with remarkably low free energy barrier of 0.31 eV, which is superior to SACs supported on graphene with sp2-hybridization. The d-band center and atomic number of the metal atom, and the charge redistribution on sp-hybridization exert significant influence to the energy of intermediates, which are key to understanding the activity and selectivity of SACs in CO2RR.