Synergy of local tip electric field mediated interfacial water activation and hydrogen spillover for alkaline seawater hydrogen evolution.

Efficient interfacial water activation and favorable hydrogen spillover (HSo) are two indispensable prerequisites for high-performance alkaline seawater hydrogen evolution reaction (HER), as both jointly govern the sluggish reaction kinetics that severely restrict seawater electrolysis toward green hydrogen production. Developing robust HER electrocatalysts capable of simultaneously optimizing these two processes therefore stands as a core demand for viable alkaline seawater hydrogen generation. In this work, we construct PtRu bimetal-decorated CoP nanorods with a hierarchical high-curvature structure that generates distinctive localized tip electric fields for enhanced alkaline seawater HER. Mechanistic investigations reveal that the tip-induced local electric field activates interfacial water and lowers the water dissociation energy barrier, while the interfacial electron density gradient drives efficient HSo. The synergy of these two effects simultaneously upgrades the HER performance in pure alkaline electrolyte and alkaline seawater. Electrochemical tests demonstrate that the catalyst requires only an overpotential of 25 mV to reach a current density of 10 mA·cm-2 in 1 M KOH, with a Tafel slope of 52.8 mV·dec-1, and can operate stably for 135 h. In the 1 M KOH + 0.5 M NaCl simulated seawater system, the performance is comparable to that in the pure alkaline electrolyte, while in the natural seawater alkaline electrolyte, it still delivers a HER activity of 68 mV@10 mA·cm-2 and operational stability over 100 h. This work elucidates the multilevel synergistic mechanism among the localized electric field, interfacial water activation and HSo, providing new insights and an experimental basis for the rational design of high-performance alkaline seawater HER catalysts.