Tailoring the Effects of Spin State and Intermediate Hydrogen Adsorption on NiPt/Ni Bridge Sites toward Robust Acidic Water Electrolysis

Precise modulation of the electronic structure in transition metals, particularly the d-band center position and spin state, remains a critical challenge to expediting hydrogen evolution reaction (HER) kinetics. Herein, we report a NiPt/Ni-heterostructured catalyst enabling simultaneous optimization of the d-band electronic structure and spin state of Ni through regulation of the NiPt and Ni bridge sites. Combining operando spectroscopy, X-ray absorption spectroscopy, density functional theory, and ab initio molecular dynamics simulations, we establish that the coordination environment and spin states of Ni at the bridge sites were effectively modulated by altering the Pt content, achieving a transition of Ni centers from the low-spin to high-spin state, and optimized intermediate adsorption/desorption behaviors. The resulting NiPt/Ni catalyst exhibits an exceptional HER performance in acidic media, achieving a benchmark current density of -10 mA cm-2 at a mere 9.8 mV overpotential and delivering an industrial-scale 1.0 A cm-2 current density in PEM electrolysis at 1.75 V.