Borophene: A Metal-free and Metallic Electrocatalyst for Efficient Converting CO2 into CH4

Exploring novel and metal-free electrocatalysts for CO2 reduction is of great significance not only for reducing of CO2 emission but also for energy storage. However, searching metal-free and highly efficient electrocatalysts for CO2 reduction is still challenging. Here, we report that a metal-free and metallic borophene can be used as an efficient electrocatalyst for CO2 reduction. Through a comprehensive DFT investigation of CO2 activation and conversion on newly fabricated metallic 2D boron sheets (borophene, beta(12) or chi(3) boron sheets), our calculational results indicate that electron deficient borophene can provide electrons to CO2 and effectively activate the inserted CO2 by breaking pi bond of CO2. Moreover, the study demonstrates that the most feasible product of CO2 reduction on the borophene is CH4 with a limiting potential of -0.27 V and the largest activation barrier of 0.98 eV along the minimum energy pathway. The very small values of the limiting potential and activation barrier indicate that CO2 reduction reaction on borophene is both thermodynamically and kinetically feasible. Overall, our work provides insight that the metal free and metallic borophene can be used as an excellent electrocatalyst for CO2 reduction.