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

Abstract

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− → ∗COOH or CO2 + H+ + e− → ∗HCOO), 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 UL(CO2) – UL(H2), so they are promising CO2RR electrocatalysts. This work provides a new kind of 2D MOFs as efficient CO2RR electrocatalysts for experimental research.