WO_x-Surface Decorated PtNi@Pt Dendritic Nanowires as Efficient pH-Universal Hydrogen Evolution Electrocatalysts

The hydrogen evolution reaction (HER) is a pivotal element of electrochemical water splitting which is able to produce clean hydrogen as an alternative to fossil fuel. Developing efficient Pt-based electrocatalysts for the HER to work at all pHs is highly desirable, however, still a significant challenge, especially in alkaline conditions due to sluggish water dissociation and OH_ad transfer. Here, a new strategy for making a class of amorphous WO_x-surface decorated PtNi@Pt dendritic nanowires (WO_x-PtNi@Pt DNWs) to achieve highly efficient pH-universal HER electrocatalysis is reported. The as-made WO_x-PtNi@Pt DNWs display superior HER performance with the overpotentials of 24, 5, and 22 mV in 0.1 m KOH, 0.1 m HClO₄, and 0.5 m phosphate-buffered saline, respectively, at a current density of 10 mA cm⁻². The mass activity of WO_x-PtNi@Pt DNWs in alkaline conditions is 3.3 mA μg_Pt⁻¹ at an overpotential of 70 mV, among the best in all the reported materials. Theoretical calculations confirm the introduction of WO_x to the PtNi DNWs plays a pivotal role in promoting the efficient electron transfer for the alkaline and acidic HER. The activation of the PtNi region within the Pt-Ni-W-O interface is achieved by the WO_x induced strain effect, which guarantees the superior performance in the HER.