By first-principles calculations, M₃B₄-type (M=Cr, Mo, Mn, Ti, Zr, Hf, V, Nb, and Ta) MBenes show good catalytic activity for the conversion of CO₂ to CH₄, where the limiting potentials of Mo₃B₄ and Cr₃B₄ are −0.48 and −0.66 V. In addition, ΔG(*OCHO) can be used as a suitable descriptor to understand the mechanism of the CO₂ reduction reaction.

Abstract

The rational design of novel catalysts with high activity and selectivity for carbon dioxide reduction reaction (CO₂RR) is highly desired. In this work, we have extensive investigations on the properties of two-dimensional transition metal borides (MBenes) to achieve efficient CO₂ capture and reduction through first-principles calculations. The results show that all the investigated M₃B₄-type MBene exhibit remarkable CO₂ 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 CO₂ to CH₄. Moreover, a new linear scaling relationship of the adsorption energies of potential-determining intermediates (*OCH₂O and *HOCH₂O) versus ΔG(*OCHO) has been established, where the CO₂RR limiting potentials on MBenes are determined by the different fitting slopes of ΔG(*OCH₂O) and ΔG(*HOCHO), allowing significantly lower limiting potentials to be achieved compared to transition metals. Especially, two promising CO₂RR catalysts (Mo₃B₄ and Cr₃B₄ 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 CO₂ capture by MBenes easier and exploit the applications of Mo₃B₄ and Cr₃B₄ MBenes as novel CO₂RR catalysts.