Short‐Path Hydrogen Spillover on CeO ₂ ‐Supported PtPd Nanoclusters for Efficient Hydrogen Evolution in Acidic Media

Hydrogen spillover in supported metal electrocatalysts has garnered significant research attention for its potential to enhance the hydrogen evolution reaction (HER) efficiency. However, challenges remain in facilitating hydrogen spillover and reducing the associated energy barriers. Herein, PtPd alloy clusters are anchored to the CeO₂ surface, enabling short-path hydrogen spillover and lowering the reaction energy barrier in acidic environments. During HER, hydrogen is initially adsorbed on the noble metal surface and subsequently migrates to the interface, rather than precipitating directly on the CeO₂ surface. This interface exhibits a near-zero Gibbs free energy of hydrogen adsorption (0.023 eV). Consequently, the catalyst demonstrates an exceptionally low overpotential of only 5.7 mV at 10 mA cm^-2 in acidic media, along with remarkable long-term stability. These findings provide valuable insights into designing highly efficient HER electrocatalysts for acidic environments based on hydrogen spillover mechanisms.