Prediction of M 3 B 4 -type MBenes as Promising Catalysts for CO 2 Capture and Reduction.

The rational design of novel catalysts with high activity and selectivity for carbon dioxide reduction reaction (CO 2 RR) is highly desired. In this work, we have extensive investigations on the properties of two-dimensional transition metal borides (MBenes) to achieve efficient CO 2 capture and reduction through first-principles calculations. The results show that all the investigated M 3 B 4 -type MBene exhibit remarkable CO 2 capture and activation abilities, which proved to be derived from the lone pair of electrons on the MBene surface. Then, we emphasize that the investigated MBenes can further selectively reduce activated CO 2 to CH 4 . Moreover, a new linear scaling relationship of the adsorption energies of potential-determining intermediates (*OCH 2 O and *HOCH 2 O) versus ΔG(*OCHO) has been established, where the CO 2 RR limiting potentials on MBenes are determined by the different fitting slopes of ΔG(*OCH 2 O) and ΔG(*HOCHO), allowing significantly lower limiting potentials to be achieved compared to transition metals. Especially, two promising CO 2 RR catalysts (Mo 3 B 4 and Cr 3 B 4 MBene) exist quite low limiting potentials of -0.48 V and -0.66 V, as well as competitive selectivity concerning hydrogen evolution reactions have been identified. Our research results make future advances in CO 2 capture by MBenes easier and exploit the applications of Mo 3 B 4 and Cr 3 B 4 MBenes as novel CO 2 RR catalysts.