Equilibrated PtIr/IrOx Atomic Heterojunctions on Ultrafine 1D Nanowires Enable Superior Dual‐Electrocatalysis for Overall Water Splitting

Abstract Dual‐active‐sites atomically coupled on ultrafine 1D nanowires (NWs) can offer synergic atomic heterojunctions (AHJs) and high atomic‐utilization toward multipurpose and superior catalysis. Here, ≈2‐nm‐thick PtIr/IrO x hybrid NWs are elaborately synthesized with equilibrated Pt/IrO x AHJs as high‐efficiency bifunctional electrocatalysts for overall water splitting. Mechanism studies reveal the atomically coupled Pt–IrO x dual‐sites are favorable for facilitating water dissociation, alleviating the binding of H* on Pt sites and inversely regulating the *OH adsorption and oxidation on bridge Ir–Ir sites. By simply equilibrating the Pt–IrO x ratio, the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) can be substantially accelerated. In particular, Pt‐rich PtIr/IrO x ‐30 NWs attain 11‐fold enhancements for HER compared to Pt/C in 1.0 m KOH, while IrO x ‐rich PtIr/IrO x ‐50 NWs express about five times mass activity referring to Ir/C for OER. Remarkably, the ratio‐optimized PtIr/IrO x NWs electrode couple achieves a durably continuous H 2 production under a substantially low cell voltage.