Abstract
Two-dimensional atomically thin hexagonal boron nitride (h-BN) monolayers have attracted considerable research interest. Given the tremendous progress in the synthesis of h-BN monolayers on transition metals and their potential as electrocatalysts, we investigate the electrocatalytic activities of h-BN/Ni, h-BN/Co, and h-BN/Cu interfaces for CO2 reduction by the first-principles density functional theory. We find that with the h-BN monolayer on the metal, electrons transfer from the metal to the interface and accumulate under the B atoms. By calculating the binding energies of three key intermediates (H, HCOO, and COOH) for hydrogen evolution and CO2 reduction, we find that H binding on the metal can be significantly weakened by the h-BN monolayer, preventing the hydrogen evolution reaction (HER). However, the binding strength of HCOO is strong on both the metal and h-BN/metal, especially for Ni and Co, promoting the CO2 reduction channel. On the basis of the free-energy diagrams, we predict that h-BN/Ni and h-BN/Co will have very good electrocatalytic activities for CO2 reduction to HCOOH, while the competitive HER channel is filtered out by the surface h-BN monolayer. Our study opens a new way for selective electroreduction of CO2 via the interface engineering of the h-BN/metal system.
