Synergistic Lewis acid-base pairs-mediated microenvironment optimization for hydrogen evolution in pH-universal and alkaline seawater

Large-scale green hydrogen production is hindered by the lack of efficient and stable electrocatalysts across wide pH ranges and in seawater. Herein, we report a rationally designed Ru-anchored oxygen-deficient MoO 2 electrocatalyst (Ru-MoO x ) featuring Lewis acid-base pairs (LABPs), where oxygen vacancies (O V ) serve as Lewis acid (LA) sites for water dissociation, while electron-rich Ru nanoparticles act as Lewis base (LB) sites for *H adsorption/desorption. This synergy enables exceptional hydrogen evolution reaction (HER) performance, with overpotentials of 8.5   mV (alkaline), 22.9   mV (acidic), 38.3   mV (neutral), and 7.3   mV (alkaline seawater) at 10   mA   cm −2 , which outperforms commercial Pt/C and most reported electrocatalysts. The Ru-MoO x exhibits long-term stability for over 100   hours across all tested media. When integrated into an anion exchange membrane electrolyzer, it achieves 1   A   cm -2 at 1.78   V and runs stably for 500   hours, demonstrating promising practical applicability. In situ Raman spectroscopy confirms that the interfacial water microenvironment is modulated and water dissociation is accelerated within the Ru-MoO x . Density functional theory calculations corroborate that LABPs can optimize *H adsorption and reduce Volmer reaction barriers, thereby significantly boosting the kinetics of the HER. This work provides a strategy for the development of high-performance, stable, and pH-universal HER electrocatalysts, thus facilitating sustainable hydrogen production from freshwater and seawater.