Computational evaluation of 2D metal-organic frameworks with TMX4-centers (X = O,S and Se) for CO2 electroreduction

Electrochemical CO₂ reduction into value-added fuels and chemicals is regarded as a highly efficient way to achieve a carbon neutral cycle. Recently, two-dimensional metal-organic frameworks (2D MOFs) have attracted much attention in CO₂ reduction reaction (CO₂RR). Herein, we employed density functional theory (DFT) to study the catalytic performance of 48 kinds of the π-d conjugated 2D layered MOFs, i.e., TM-BHX, composed of transition metal ions and multidentate organic ligands, such as benzenehexaol (BHO), benzenehexathiol (BHT) and benzenehexaselenolate (BHS), for CO₂RR. By investigating the thermodynamic stability and electrochemical stability, conductivity and the free energy change of the first hydrogenation step (CO₂ + H⁺ + e^? → 1COOH or CO₂ + H⁺ + e^? → 1HCOO), nine TM-BHX were selected from 48 MOFs, including TM-BHT (TM = Cr, Fe, Co, Ru, Rh, Ir) and TM-BHS (TM = Ru, Rh, Ir). Possible reaction pathways of CO₂ reduction into C1 products were explored to determine the CO₂RR mechanism. Our results showed that among 9 candidates, Cr-, Fe-, Co-BHT, and Ir–BHS not only exhibit high activity with low limiting potential (?0.30, ?0.29, 0, and ?0.49 V, respectively), but also have high CO₂RR selectivity with the positive value of U_L(CO₂) – U_L(H₂), so they are promising CO₂RR electrocatalysts. This work provides a new kind of 2D MOFs as efficient CO₂RR electrocatalysts for experimental research.