Transition-Metal Diboride: A New Family of Two-Dimensional Materials Designed for Selective CO₂ Electroreduction

From both energy and environmental points of view, it is highly desirable to produce organic compounds from greenhouse gas CO 2 . To reach such an attractive goal, high-performance catalysts are required. In this study, a new family of two-dimensional (2D) materials, transition-metal diboride (MB 2 ), are theoretically designed. With intrinsic transition-metal-terminated surfaces, MB 2 monolayers exhibit a high catalytic activity for the conversion of CO 2 selectively to CH 4 . In particular, the OsB 2 monolayer has an ultralow limiting potential of −0.4 V for CH 4 production. Non-noble-metal-based FeB 2 and MnB 2 also have a low limiting potential, and they are thus very promising for practical applications. Atomistic mechanisms of the catalyzed CO 2 conversion are understood based on the first-principles calculations. Oxygen binding energy is found to be a good descriptor for the catalytic performance, and the activity “volcano” plot suggests that, in the OsB 2 case, it is very close to the optimal value of 6.4 eV. The outstanding catalytic performance of this new type of 2D materials makes them especially attractive for CO 2 utilization.