Updating the Intrinsic Activity of a Single-Atom Site with a P–O Bond for a Rechargeable Zn–Air Battery

Rechargeable Zn-air batteries have drawn great attention over the past decade, but their further development will require efficient bifunctional electrocatalysts to drive the sluggish cathodic reactions. Although a single-atom catalyst with maximum utilization per metal atom shows great promise, its catalytic performance is still far from satisfactory. Here we tackle this challenge by introducing a P-O bond to update the intrinsic activity of a single-atom site and thus reduce the reaction overpotential of the Zn-air battery. The critical role of the P-O bond in producing a favorable surface electronic environment of the single-atom metal site and improving its catalytic activity is identified with density functional theory simulations. The P-O-doped, atomically dispersed catalyst is shown experimentally to deliver excellent bifunctional performance, with a remarkable half-wave potential of 0.89 V versus reversible hydrogen electrode (vs RHE) for oxygen reduction reaction and a reversible oxygen electrode index of 0.74 V, exceeding those of most reported nonprecious metal catalysts. When subjected to practical application, both aqueous and all-solid-state Zn-air batteries illustrate superior power density and robust cyclic performance, confirming their potential feasibility in next-generation electronic devices.