Theoretical Evaluation of MBenes as Catalysts for the CO2 Reduction Reaction

Electrochemical reduction of carbon dioxide (CO2) to high-value-added products is a promising strategy for mitigating the greenhouse effect and energy shortage. Designing a high-performance electrocatalyst with a low limit potential and tunable reaction path is a critical challenge for CO2 reduction. Two-dimensional (2D) nanostructured materials are considered as competitive catalysts for electrochemical reduction due to their large specific surface area and rich active sites. The current work theoretically evaluates four 2D MBene nanosheets as potential catalysts for CO2 reduction. It is found that Mo2B2 and Cr2B2 show good catalytic selectivity due to their poor hydrogen evolution reaction (HER) performance and low limit potential for CO2 reduction. We found that the Gibbs energy increase for CHO formation is the highest on all MBenes. Among them, Mo2B2 and Cr2B2 maintain a lower limit potential with values of −0.45 and −0.5 eV, respectively. The electronic structure analysis demonstrates that the electron migration from MBene substrates to the antibonding states of adsorbates can lower the Gibbs free energy of hydrogenation reactions of intermediate products.