Computational screening of homo and hetero transition metal dimer catalysts for reduction of CO2 to C2 products with high activity and low limiting potential

Abstract

C₂ products such as ethylene and ethanol play a critical role in the chemical and fuel industry, and electrochemical reduction of CO₂ to C₂ products is a recognized environmentally friendly and efficient way. Exploring high-performance electrocatalysts for the CO₂ reduction reaction (CRR) with high activity and low limiting potential for C₂ products has become a critical issue. In order to investigate the advantages of the synergistic effect in dual metal active sites for the CRR, in this study, we propose a systematic computational screening of bimetal dimer (including homo and hetero-transition metal atoms) embedded nitrogen doped graphene as double metal catalysts (DACs) for CO₂ reduction to ethylene and ethanol using density functional theory. After screening of 21 DACs with the adsorption free energy of *H and *OH, and the threshold value of limiting potential (−0.80 V), we obtain nine promising candidates for C₂ products. After the second-round screening based on the C–C coupling process, six DACs exhibit acceptable activity and limiting potential for the CRR to C₂ products. The limiting potentials are −0.58 V (Cr–Cu), −0.75 V (Mn–Cu), −0.45 V (Co–Co), −0.78 V (Co–Ni), −0.65 V (Co–Cu), and −0.80 V (Ni–Cu) for C₂ compounds, and for Cr–Cu, Mn–Cu, Co–Ni, Co–Cu, and Ni–Cu, the energy barrier of C–C coupling is much lower than the threshold value (+0.75 eV) with a much easier coupling process. Moreover, these promising DACs show high thermal stability with negligible structural distortion at 500 K. Our work provides theoretical insights for the development of double TM based electrocatalysts to reduce CO₂ to C₂ products with distinguished activity.