Electronic perturbation by interfacial coupling of iridium cluster and Cu₃P accelerates water splitting kinetics

Clarifying the ambiguous correlation between the coordination/electronic state and reactivity of heterogeneous catalysts is crucial in designing high-performance water-splitting catalysts. Herein, the metal-support interaction is constructed by interfacial coupling of iridium (Ir) cluster and metal-rich copper monophosphide (IrCL@Cu3P). Based on refined structural characterization and theoretical calculations, the interfacial coupling leads to shrinkage in the Ir-Ir bond distance and significant charge transfer from the cluster to the substrate, which brings about an electronic perturbation and breaks the improper charge distribution, promoting water-splitting kinetics. The fabricated catalyst yields superior bifunctional activities toward hydrogen and oxygen evolution reactions with overpotentials as low as 21 and 216 mV at the current density of 10 mA cm(-2) in alkaline electrolyte, respectively. Moreover, the practical application is verified in the alkaline membrane electrode assembly, which shows an electrolyzer voltage of as low as 1.94 V at 1 A cm(-2) with the fabricated catalyst working as both the anode and cathode. Precisely tuning electronic perturbation by interfacial coupling could provide valuable insights into designing highly efficient water splitting catalysts and beyond.