Ni₃ N as an Active Hydrogen Oxidation Reaction Catalyst in Alkaline Medium

Hydroxide-exchange membrane fuel cells can potentially utilize platinum-group-metal (PGM)-free electrocatalysts, offering cost and scalability advantages over more developed proton-exchange membrane fuel cells. However, there is a lack of non-precious electrocatalysts that are active and stable for the hydrogen oxidation reaction (HOR) relevant to hydroxide-exchange membrane fuel cells. Here we report the discovery and development of Ni₃ N as an active and robust HOR catalyst in alkaline medium. A supported version of the catalyst, Ni₃ N/C, exhibits by far the highest mass activity and break-down potential for a PGM-free catalyst. The catalyst also exhibits Pt-like activity for hydrogen evolution reaction (HER) in alkaline medium. Spectroscopy data reveal a downshift of the Ni d band going from Ni to Ni₃ N and interfacial charge transfer from Ni₃ N to the carbon support. These properties weaken the binding energy of hydrogen and oxygen species, resulting in remarkable HOR activity and stability.