Enhancing carbon activity in C@hcp-NiPt/NF electrocatalyst for pH-universal hydrogen evolution

Charge redistribution strategy driven by geometry regulation of metal cores or carbon defect engineering is an effective approach to optimize the electronic structure of traditional carbon, which can boost hydrogen evolution reaction (HER) activity to inert carbon. The synergistic effect of these two methods is anticipated to more effectively manipulate the charge distribution of carbon materials. Herein, a facile low-temperature methane plasma strategy is developed, from which highly dispersive hexagonal close-packed (hcp) NiPt alloy encapsulated in the defect-rich carbon shell grown on the Ni foam (C@hcp-NiPt/NF) can be fabricated. The optimized C@hcp-NiPt/NF displays low overpotentials of 60, 110, and 60 mV at 100 mA cm^-2 in 1.0 M KOH, 1.0 M PBS, and 0.5 M H₂SO₄, respectively. Furthermore, it demonstrates exceptional stability under alkaline, neutral and acidic conditions. Raman spectroscopy, in-situ electrochemical impedance spectroscopy (EIS), combined with theoretical calculations have unequivocally validate that the incorporation of carbon defects and the regulation of geometric structure in NiPt cores significantly augment the charge density on the carbon shell, thereby optimizing the binding affinity of carbon with H₂O and hydrogen, ultimately resulting in improved HER performance.