The OH--driven synthesis of Pt-Ni nanocatalysts with atomic segregation for alkaline hydrogen evolution reaction

Intense researches for pursuing effective catalysts for alkaline hydrogen evolution reaction (HER) have been carried out. Particularly, Pt-based materials having heterostructures have shown excellent electrocatalytic performance. However, there are only few investigations on the transformation from an alloy to a heterostructure and the main reason for superior activity. Herein, we demonstrated that Pt-Ni heterostructures could be formed by only introducing NaOH in the synthesis of Pt-Ni alloys. Density functional theory calculations revealed that the added OH- can influence the energy barriers of atomic reduction and migration, thus driving the formation of a heterostructure with atomic segregation. Moreover, it was proved that the enhanced HER performance is attributed to favorable H and OH energetics arising from the atomic segregation. Acid treatment emphasized the key factors in determining the activity. This work proves that adding OH- can lead to the formation of nanocatalysts with atomic segregation, and tuning the atomic segregation of Pt-Ni catalysts is an effective way to optimize their H and OH adsorption abilities, thus enhancing the alkaline HER performance.