B2O and B4N monolayers supported single-metal atom as highly efficient bifunctional electrocatalyst for OER and ORR

The development of high efficiency, stable and economical electrocatalysts is an ideal choice for water electrolysis, fuel cells and metal air cells, and an important innovation in the future energy field. Bifunctional or even multifunctional catalysts have higher performance and lower cost than monofunctional catalysts, which is currently an emerging focus in the development of electrocatalysts. The single-atom catalysts (SACs) of two-dimensional (2D) materials-supported transition metal (TM) atoms have attracted great attention because of their ability to make full use of metal atoms and remarkable catalytic performance. In this work, the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) catalytic properties of B4N and B2O monolayers supported TM atoms have been systematically evaluated based on first-principles calculations. The adsorption free energy of key intermediates (OOH*, O* and OH*) on the catalyst determines the catalytic activity toward OER and ORR. The calculation results exhibit that Ni@B4N and Pd@B2O systems are potential bifunctional electrocatalysts with the overpotential (η) of OER/ORR being just 0.45/0.43 V and 0.56/0.47 V, respectively, which are comparable to the known noble metal catalysts. Therefore, the study of catalytic activity of SACs on 2D substrate materials provides a broad prospect for the development of stable, low-cost, high-activity noble metal-free electrocatalysts, and provides help for solving energy and environmental problems.