Computational screening of homo and hetero transition metal dimer catalysts for reduction of CO2 to C-2 products with high activity and low limiting potential

摘要

C-2 products such as ethylene and ethanol play a critical role in the chemical and fuel industry, and electrochemical reduction of CO2 to C-2 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 C-2 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 C-2 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 C-2 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 C-2 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 C-2 products with distinguished activity.