Atomic-scale effect of 2D conjugated metal-organic frameworks as electrocatalysts for CO2 reduction reaction towards highly selective products

Electrocatalytic CO₂ reduction reaction (CO₂RR) is key to mitigating greenhouse gas emissions and the energy crisis. However, controlling the selectivity of CO₂RR products at low overpotentials remains a challenge. Herein, two-dimensional (2D) conjugated metal-organic frameworks (MOFs) with the single atomic active centers were proposed by varying the combinations of different metals and organic ligands, on which their stability, electrocatalytic CO₂RR activity and product selectivity were theoretically investigated. Five high performance CO₂RR catalysts with specific products (HCOOH, CH₂O, CH₃OH and CH₄) were identified through the CO₂RR mechanism and HER competitive screening. Furthermore, the mechanistic differences resulting from the competitive selectivity of carbon- and oxygen-bound species can be directly determined from the scaling of adsorption energies between COOH and HCOO. In addition, the adsorption energies of COOH/HCOO and the number of electrons involved in CO₂RR depend on the location of the d-band center of 2D conjugated MOFs. Thus, the selectivity of the product can be directly influenced by modulating the d-band center of the active site. Therefore, manipulating metals and ligands allows us to tune the structure-property relationship in 2D conjugated MOFs to design and optimization of highly active and product-specific CO₂RR electrocatalysts.