Computational screening of single-atom catalysts for direct electrochemical NH3 synthesis from NO on defective boron phosphide monolayer

Abstract

Selective electrocatalytic reduction of NO to ammonia provides a promising way to remove pollutant NO and realize green ammonia synthesis under ambient conditions. The key to promote the practical application of NO reduction reaction (NORR) is to develop economical and efficient electrocatalysts to replace Pt-based catalysts. In this work, we designed a series of transition metal (TM) single-atom catalysts (SACs) supported on BP monolayer with a B vacancy (TM@BP, TM = Ti ∼ Zn, Zr ∼ Ag, and Hf ∼ Au), and systematically investigated their performance of electrocatalytic NORR by means of density functional theory (DFT). Taking the changes of free energy of the first (NO → NOH/NO → NHO) and last (OH → H2O/NH2 → NH3) hydrogenation steps of NORR as the screening criteria, seven TM@BP (TM = Ti, V, Cu, Rh, Ag, Ir, and Au) were selected from eighteen candidates. All possible reaction pathways of NORR to produce NH3 and byproducts (N2O, N2 and H2) were considered. Our calculated results show that Ti@BP, V@BP, Cu@BP, and Au@BP not only exhibit similar catalytic activity to Pt-based catalysts, but also have excellent NORR selectivity toward NH3, so they are predicted to be the most promising catalysts. This work provides useful guidance for the design and exploration of efficient NORR electrocatalysts.