Understanding the Activity and Design Principle of Dual-Atom Catalysts Supported on CN for Oxygen Reduction and Evolution Reactions: From Homonuclear to Heteronuclear.

Using large-scale calculations and taking the two-dimensional CN monolayer as a substrate, we sampled a large combinatorial space of CN-supported homonuclear and heteronuclear dual-atom catalysts and built a detailed view of catalytic activity and stability toward the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). The results indicate that regulating combinations of metal pairs could widely tune the catalytic performance. Pd-, Pt-, and PdPt-CN could effectively balance the adsorption strength of intermediates and achieve optimal bifunctional activity. The favorable catalytic performance could also be realized on GaPd-CN for the ORR and PdRh-CN for the OER, surpassing corresponding homonuclear counterparts. The thermodynamic and electrochemical stability simulations reveal that these metal pairs can be stably anchored onto the CN matrix. Multiple-level descriptors, including Gibbs free energy, d-band center, and bonding/antibonding orbital population, are established to track the activity trend and reveal the origin of activity, indicating that catalytic activity is intrinsically governed by the d-band center of metal pairs.