Critical Role of Support-Dependent Water Dissociation in the Alkaline Hydrogen Evolution on Single-Atom Platinum Catalysts

Single-atom catalysts (SACs) provide a promising strategy to minimize precious-metal loading while simultaneously preserving high catalytic performance in alkaline hydrogen evolution reaction (HER). However, slow water dissociation kinetics in alkaline electrolytes remain a major bottleneck for efficient HER. Herein, we design and synthesize single-atom platinum on Fe3O4, Fe2O3, and carbon fiber paper (CFP) supports (i.e., Pt1/Fe3O4, Pt1/ Fe2O3, and Pt1/CFP, respectively) to demonstrate the role of support-dependent interfacial water dissociation in alkaline HER. The distinct Fe3O4 phase induces favorable electronic modulation, promoting water dissociation and optimizing intermediate adsorption, whereas Fe2O3 and carbon supports exhibit weaker interfacial coupling and higher dissociation barriers, resulting in slower HER kinetics. Consequently, Pt1/Fe3O4 achieves optimal alkaline HER activity of ∼46 mV at 10 mA cm−2 and ∼103 mV at 100 mA cm−2, compared with 126 and 307 mV for Pt1/ Fe2O3 and 65 mV and 168 mV for Pt1/CFP at the same current densities, outperforming reported Pt-based single-atom catalysts. These findings demonstrate that the support plays a critical role in interfacial water activation and HER kinetics, providing insights for the development of efficient single-atom electrocatalysts.