Phase and interface engineering of nickel carbide nanobranches for efficient hydrogen oxidation catalysis

The hydrogen oxidation reaction (HOR) has recently attracted great attention, yet the poor performance of HOR over the platinum group metal-free (PGMs-free) catalysts in alkaline conditions strongly impedes the development of hydroxide-exchange membrane fuel cells. Here, we demonstrate that the phase and interface engineering of nickel carbide (Ni3C) nanobranches can significantly enhance the alkaline HOR performance. Specifically, such interface engineering is realized through a facile annealing treatment of a branched Ni3C nanostructure. As a promising PGMs-free HOR catalyst, the strong interfacial synergy of Ni/Ni3C significantly enhances the HOR performance in alkaline media, with the HOR activity being comparable to that of a commercial Pt/C catalyst, and it demonstrates excellent CO tolerance. Mechanism studies show that the interfacial synergy facilitates electron transfer from Ni to Ni3C and thus regulates the absorption strengths of *H and *OH. This work opens up a new avenue for the design of high-performance PGM-free catalysts for electrocatalysis and beyond.