Asymmetrical Fe−Se−Ru Active Sites in Ruthenium Diselenide Nanocrystals Boost Stable Ampere‐Level Hydrogen Evolution in Alkaline Seawater

ABSTRACT Achieving both high activity and long‐term stability in alkaline seawater electrolysis remains challenging. To tackle this, we devise a synergistic engineering strategy that integrates iron doping with vacancy creation to tailor the local coordination environment of RuSe 2 via a hydrothermal method followed by ultrafast Joule heating, which enables the simultaneous construction of asymmetric Fe−Se−Ru sites and Se vacancies. The optimal catalyst delivers ultralow overpotentials of 12 mV (alkaline water) and 20 mV (alkaline seawater) at 10 mA·cm −2 , outperforming commercial Pt/C. In an anion exchange membrane water electrolyzer, it achieved a cell voltage of only 1.87 V at 1.0 A·cm −2 in alkaline seawater and operated stably for 1000 h. Combined experimental characterizations and theoretical calculations reveal that the superior activity and stability originate from the synergy of asymmetric Fe−Se−Ru sites and Se vacancies, which enhances water dissociation, optimizes hydrogen adsorption, and suppresses chloride corrosion. This work provides a rapid route to high‑performance Ru‑based catalysts for durable seawater electrolysis.