DFT study of the electrochemical CO2 reduction by Sc to Ni single atom catalysts implanted on the pristine and N-doped-H4,4,4-graphyne

Abstract

The electrochemical reduction of CO2 to valuable chemicals and fuels can mitigate the energy crisis and environmental challenges. Finding the stable and efficient catalysts with high selectivity is essential for successful CO2 reduction. In this study, the catalytic activity of the transition metals (TMs) (Sc to Ni), as single-atom catalysts (SACs), on the pristine, N-doped, TM decorated and simultaneous N-doped and TM decorated H4,4,4- GY monolayers was investigated for CO2 reduction reaction (CRR) using DFT-D2 calculations. The results reveal that among three metal-free monolayers, the Nsp/H4,4,4-GY exhibits superior CO2 reduction compared to others. The investigation of CRR on TM-H4,4,4-GY, TM-Nsp/H4,4,4-GY, and TM-Nsp2/H4,4,4-GY monolayers reveals that CrH4,4,4-GY, Cr-Nsp/H4,4,4-GY, and Mn-Nsp2/H4,4,4-GY monolayers have the best performance among the eight TMdecorated carbon frames. The selectivity and activity of the CRR and HER for pristine and TM decorated monolayers were investigated. It was seen that the Cr-H4,4,4-GY, Cr-Nsp/H4,4,4-GY, and Cr and Mn-Nsp2/H4,4,4-GY have better catalytic activity and selectivity than other monolayers. With respect to the volcano curves, Ti-H4,4,4- GY, Co-Nsp/H4,4,4-GY, and V-Nsp2/H4,4,4-GY catalysts show superior HER catalytic activity; whereas HER does not compete with CRR for the best SACs (Cr and Mn) on the monolayers