Pt‐SnO x Clusters With Weak Interfacial Interaction Boost Hydrogen Evolution

Downsizing noble metal catalysts (e.g., Pt) is critical for enhancing atomic efficiency in sustainable energy applications. Herein, we report a Pt–SnO x nanocluster (NC) system featuring weak Pt/SnO x interfacial interaction, which enables SnO x to effectively modulate the reaction pathway without compromising the intrinsic Pt catalytic properties. Notably, characterization results reveal negligible charge transfer at the interface. The Pt–SnO x NCs exhibit an overpotential of 22 mV at 10 mA cm −2 and a Tafel slope of 24 mV dec −1 , outperforming Pt NCs, Pt nanoparticles, and Pt–SnO 2 structures with strong interfacial interactions. Theoretical calculations suggest that the Pt–SnO x architecture facilitates hydrogen spillover, which may promote a shift in the dominant hydrogen evolution reaction (HER) mechanism from Volmer–Heyrovsky to a more efficient Volmer–Tafel route. As the cathode in an ethanol‐assisted proton exchange membrane paired‐electrolyzer, the Pt–SnO x NC catalyst delivers 1.0 A cm −2 at below 1.5 V under 80°C with stable operation over 70 h.