Multi-interfacial engineering of IrO_x clusters coupled porous zinc Phosphide-Zinc phosphate heterostructure for efficient water splitting

Herein, a heterostructured electrocatalyst derived from ultrasmall iridium (3.85 wt%)-based clusters (IrO_x) integrated zinc phosphide (Zn₃P₂)-zinc phosphate (ZnPi) nanosheets (NSs) is rationally fabricated by a facile approach. The IrO_x/Zn₃P₂-ZnPi NSs catalyst possesses efficient catalytic activities and prospective stability due to its large electroactive surface area, excellent charge transfer, high mechanical properties of the structure, and good catalyst-substrate interactions. As a result, the IrO_x/Zn₃P₂-ZnPi NSs catalyst exhibits an overpotential of 106 mV for hydrogen evolution reaction (HER) and 286 mV for oxygen evolution reaction (OER) to reach a current output of 10 mA cm⁻² in 1.0 M KOH medium, which are significantly lower than those of the IrO_x/Zn₃P₂-ZnPi nanorods (NRs) and previously reported bifunctional electrocatalysts. An electrolyzer derived from the IrO_x/Zn₃P₂-ZnPi NSs_(+,-) requires a small cell voltage of 1.62 V at 10 mA cm⁻² and 1.84 V at 100 mA cm⁻², surpassing behaviors of a commercial Pt/C_(-)//IrO₂₍₊₎ system. The results indicate that the IrO_x/Zn₃P₂-ZnPi NSs is a potential bifunctional electrocatalyst for efficient water splitting application to produce green hydrogen fuel.