In Situ Active Site Refreshing of Electro‐Catalytic Materials for Ultra‐Durable Hydrogen Evolution at Elevated Current Density

Abstract Enhancing the durability of catalysts is of critical significance to industrialize green hydrogen production. Herein, a novel active site in situ refreshing strategy is proposed and demonstrated to fabricate highly active and ultra‐durable hydrogen evolution reaction (HER) electro‐catalytic material by HER activation. Briefly, a composite catalytic material is synthesized, which features Ni(PO 3 ) 2 active sites being embedded inside the amorphous Mo compound matrix (named NiMoO‐P). The Mo compound matrix undergoes gradual dissolution during HER followed by a dynamic equilibrium between the dissolution and deposition of the amorphous matrix. This process promotes the continuous exposure of insoluble Ni(PO 3 ) 2 and Ni 2 P partially converted from Ni (PO 3 ) 2 in situ on the surface during HER activation. Thus, activated catalyst exhibits excellent HER performance featuring an extremely high current density of 1500 mA cm −2 at a rather low overpotential of 340 mV, and more attractively, an ultra‐long durability for hydrogen evolution for at least 1000 h at an industrial‐applicable current density of 900 mA cm −2 . The mechanisms for the especially high HER performance are attributed to the exposure and continuous refreshing of Ni(PO 3 ) 2 and the in situ formed Ni 2 P during the HER process based on the DFT calculations and quasi‐in situ Raman spectroscopic monitoring.