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

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/IrOx hybrid NWs are elaborately synthesized with equilibrated Pt/IrOx AHJs as high‐efficiency bifunctional electrocatalysts for overall water splitting. Mechanism studies reveal the atomically coupled Pt–IrOx 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–IrOx ratio, the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) can be substantially accelerated. In particular, Pt‐rich PtIr/IrOx‐30 NWs attain 11‐fold enhancements for HER compared to Pt/C in 1.0 m KOH, while IrOx‐rich PtIr/IrOx‐50 NWs express about five times mass activity referring to Ir/C for OER. Remarkably, the ratio‐optimized PtIr/IrOx NWs electrode couple achieves a durably continuous H2 production under a substantially low cell voltage. Ultrafine PtIr/IrOx hybrid nanowires with equilibrated Pt/IrOx atomic heterojunctions are elaborately synthesized to serve as high‐performance dual‐function electrocatalysts for overall water splitting in alkaline conditions. Atomically coupled Pt–IrOx dual‐sites can mutually arouse electronic‐modulation for substantially accelerating the hydrogen evolution reaction and oxygen evolution reaction, respectively.