How the surface Cu layer affected the activity of Ni foil for alkaline hydrogen evolution

Synthesizing bimetallic nanomaterials, with noble metals as the surface layers and inert metals as the substrates, has been proven to be an effective way to reduce the use of noble metals with maintained catalytic activity. However, an atomic diffusion from the inert substrate to the surface during the long-term operation has been reported to significantly decrease the activity. In this work, a series of catalysis-inert Cu-coated Ni foil were fabricated through electrodeposition and their activities for alkaline hydrogen evolution were investigated. Notably, the Ni/Cu-60 sample showed a similar catalytic property with pure Ni foil and only a slight decrease in HER activity was observed. The X-ray photoelectron spectroscopy (XPS) results indicated a decreased electron concentration of Cu in Ni/Cu-60, and theoretical calculations further demonstrated the electron transfer between the Ni substrate and Cu layer. Our results reveal that a specific composition or structure of an inert metal layer might not significantly decrease the electrocatalytic activity of active metals. Moreover, there are more possibilities for the rational design of metal-based catalysts for electrocatalysis.