Boosting Hydrogen Transfer during Volmer Reaction at Oxides/Metal Nanocomposites for Efficient Alkaline Hydrogen Evolution

Developing efficient and robust Earth-abundant hydrogen evolution reaction (HER) catalysts is crucial for the scalable and sustainable production of hydrogen. This study builds on the promising concept of oxide/metal nanocomposites, namely NiO/Ni, by incorporating another metal (in this case, Mo) into NiO to tune the adsorption energy of hydrogen (H). Theoretical and experimental approaches are combined to design Mo-NiO/Ni nanocomposites for efficient HER in alkaline media. The incorporation of Mo into NiO weakens the adsorption of H, favoring its transfer to nearby Ni active sites to accelerate the Volmer reaction, and also stabilizes the crystal structure of NiO. The Mo-NiO/Ni catalyst exhibits a 50 mV overpotential at a current density of -10 mA cm^-2 with a Tafel slope of 86 mV dec^-1, indicating that it is one of the most promising alkaline HER electrocatalysts reported to date. These findings suggest design principles for inexpensive, efficient, and high-performance Earth-abundant HER catalysts.