Boron-Activated Single-Metal-Site Catalysts Break Adsorption-Energy Scaling Relations for Robust Bifunctional Oxygen Catalysis.

The electrocatalytic oxygen evolution and reduction reaction (OER/ORR) catalysts are paramount to many renewable energy technologies. Atomically-dispersed transition-metal catalysts are compelling alternatives to current dominant noble-metal catalysts, yet they often show inadequate activity for OER and insufficient durability in practical battery operations. Here, we show a rational methodology that enables single-metal-site catalyst to break universal adsorption-energy scaling limitations for both OER/ORR and push bifunctional catalytic performance of transition-metal-dominated catalysts to unprecedented level. Other than metal-nitrogen coordination, the newly-designed catalyst (namely metal-C-B) stabilizes atomic metals on B-doped carbon via metal-carbon coordination and afford favorable electronic engineering. The optimized Co-C-B catalyst in base exhibits a record-low OER overpotential of 172 mV at 10 mA cm and a superior ORR half-wave potential of 0.87 V with robust stability over 500 h of continuous OER or ORR, which endows a rechargeable Zn-air battery with over 6755 charge/discharge cycles. The delivered mass activities of 33941 A g for OER and 15873 A g for ORR are respectively ∼112/80-fold higher than those of commercial noble-metal counterparts. Atomically-dispersed CoCBᵪ moieties were theoretically identified as unique bifunctional active centers, breaking usual scaling relations of intermediates adsorption and boosting inherent OER/ORR activities simultaneously beyond theoretical limitations for single metal site.