Decoration of Ir clusters accelerates the generation of active species for high-efficient overall water splitting

Noble metal decoration is one of the most efficient strategies to enhance the activity of electrocatalysts for hydrogen/oxygen evolution reaction (HER/OER). However, there is still lack of a comprehensive picture of how such strategy enhances the activity due to the complicated surface reconstructions and various electronic interactions on electrocatalysts during reactions, severely hampering the widespread utilizations of this strategy. Herein, we report that decorating Ir clusters on Fe doped Ni 2 P (Ir@Ni 2 P(Fe)) can reinforce the reconstruction of Ni 2 P(Fe) to generate more real active species via promoting the leaching of P element and ultimately improve the activities for both HER and OER. Specifically, such reinforcement leads to a considerably enhanced electron transfer and a substantially increased amount of active sites, ultimately playing a dominant role in boosting the HER performance from 176 mV over Ni 2 P(Fe) to 35 mV over Ir@Ni 2 P(Fe) at 10 mA cm −2 . As for OER, in addition to increasing the amount of active sites via the reinforcement, the decoration of Ir clusters provides high-valence Ir sites as extra efficient active centers, thereby resulting in dual promotional effects to enhance the activity from 270 to 200 mV at 10 mA cm −2 . Finally, using Ir@Ni 2 P(Fe) as both the anode and cathode, a low cell voltage of 1.50 V is required to derive a current density of 10 mA cm −2 for overall water splitting. The developed comprehensive insight is of clear significance to design advanced bifunctional electrocatalysts for overall water splitting.