Building up the “Genome” of bi-atom catalysts toward efficient HER/OER/ORR

Abstract

The search for efficient, stable, and low-cost electrocatalysts toward the water splitting and oxygen reduction reaction (ORR) in acidic media is of great significance to develop renewable energies, but remains an ongoing challenge. Herein, by employing large-scale density functional theory computations, we demonstrate that atomically dispersed bi-atom catalysts (BACs) could act as a versatile design platform to achieve efficient electrochemical hydrogen evolution reaction (HER), oxygen reduction reaction (OER), and ORR activity. Through regulating bi-atom combinations on a g-CN substrate, a materials genome containing 26 homonuclear and 253 heteronuclear BACs (M₂/g-CN and M_IM_II/g-CN) is built. Eight, one and three BACs go beyond the activity benchmark of Pt(111) and IrO₂(110) surfaces and have excellent performance for the HER, OER, and ORR, respectively. Especially, PdNi/g-CN and AgPt/g-CN exhibit a negligible potential barrier for the HER. AuRh/g-CN shows a small overpotential of 0.35 V for the ORR. AgPd/g-CN has promising bifunctional activity for both the OER and ORR with small overpotentials of 0.43 and 0.48 V respectively. AuCo/g-CN reveals tremendous trifunctional activities (with an overpotential of 0.05 V for the HER, 0.52 V for the OER, and 0.48 V for the ORR). A kinetic simulation further verifies their catalytic performance. Finally, a machine-learning technique is employed to establish the internal relationship between the HER/OER/ORR, and identify the key characteristic factors that govern the catalytic performance including the geometry parameters of the M–M–N₆ (M_I–M_II–N₆) moiety. This work not only provides a comprehensive view of BACs for water splitting and the ORR, but also presents a new path for designing and searching for efficient BACs toward electrochemical reactions.