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–SnO₂ 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.