Self‐integration exactly constructing oxygen‐modified MoNi alloys for efficient hydrogen evolution

Abstract

AbstractIntroducing oxygen atoms into nickel‐based alloys is an effective strategy for constructing water dissociation sites for hydrogen evolution reaction (HER). However, controlling oxygen content to realize the best match of water dissociation and hydrogen adsorption is challenging. Herein, we exploit the self‐integration process of MoNi alloy in molten salts to introduce oxygen atoms, which ultimately leads to the localized generation of robust NiOxHy around the MoNi alloys. Interestingly, Mo is further doped into NiOxHy (Mo‐NiOxHy) to construct an effective active center for water dissociation due to the high mobility in ionic solutions. Owing to the covering and space confinement of molten salt, MoNi alloy is exactly decorated with Mo‐NiOxHy nanosheets. Both physical characterization and density functional theory calculation prove that the electron transport, water dissociation capability, and hydrogen adsorption of MoNi are finely tuned and benefited from the O and Mo doping, thus greatly expediting HER kinetics. Mo‐NiOxHy exhibits a much lower overpotential of 33 mV at 10 mV cm−2 in alkaline electrolyte, even superior to the Pt/C benchmark. Moreover, the final Mo‐NiOxHy requires a low overpotential of 57 mV at 10 mV cm−2 in acidic media. This enhancement is ascribed to the successful assembly of MoNi foam elicited by molten salt.