Regulating Volmer-Tafel Kinetics in NiPt_1% Alloy by Oxyphilic Y-Doped NiO for Enhancing Large-Current Hydrogen...

Developing highly efficient catalysts with ultralow-loading metal is still hindered by the sluggish Volmer-Tafel kinetics for the alkaline hydrogen evolution reaction (HER). Herein, an efficient catalyst was designed and constructed on nickel foam by integrating oxyphilic Y-doped NiO with NiPt_1% nanocrystalline via a facile one-step electrodeposition. It requires only 21.2 and 178.5 mV to achieve 10 and 1000 mA cm^-2, with a low Tafel slope of 27.8 mV dec^-1. Furthermore, it provides an ultrahigh mass activity of 42.7 mA μg_pt^-1 @ 100 mV and a high stability over 2000 h at 1 A cm^-2 almost without potential decay. In-situ experiments and D₂O electrolysis tests reveal that the oxyphilic Y-NiO component not only reduces the activation energy of NiPt_1% alloy by 32% and enhances its surface hydrogen (*H) coverage 7.8 times but also markedly boosts the Volmer step. Density functional theory calculations further reveal that Y-NiO strengthens water adsorption and shifts both Volmer and Tafel steps on the NiPt_1% alloy surface from nonspontaneous to spontaneous, while reducing their energy barriers by 32 and 23%, respectively. This work presents an effective approach for regulating the Volmer-Tafel process in ultralow-loading metal alloys for alkaline HER.