Efficient electrocatalytic reduction of NO to ammonia on BC3 nanosheets.

Abstract

Searching for an economical and highly efficient electrocatalytic reduction catalyst for ammonia synthesis under controllable conditions is a very attractive and challenging subject in chemistry. In this study, we systematically studied the electrocatalytic performance of BC3 nanosheets as potential NO reduction reaction (NORR) electrocatalysts using density functional theory (DFT) calculations. It was found that BC3 two-dimensional (2D) materials exhibit excellent catalytic activity with a very low limiting potential of -0.29/-0.11 V along three reaction paths. The total reaction is NO (g)+5H++5e-→NH3(g)+ H2O. The density of states of adsorbed NO, NH3, and the corresponding crystal orbital hamiltonian population (COHP) analysis revealed the mechanism of NO being activated and the reasons for NH3 adsorption/desorption on the surface of BC3. The reaction path, limiting potential, and Gibbs free energy calculations of BC3 catalyzed NO to ammonia synthesis revealed that for path 1, the potential-determining step is *NO+H++e-→*NOH, and for path 2/3 the potential-determining step is *NO+(H++e-)→*HNO. Calculation of the thermodynamic energy barriers for NO dissociation at the BC3 surface and NO hydrogenation reveals that NO is more likely to be hydrogenated rather than dissociated. The influences of the proton-electron hydrogenation site on the process of ammonia synthesis in the key reduction step were analyzed by Bader charge analysis and charge density, it is pointed out that the electronic structure and affects the reaction process can be controlled by hydrogenation at different sites of intermediates. These results pave the way for using nitrogen oxides not just nitrogen as raw materials for ammonia synthesis with 2D materials.