ABSTRACT The advancement of highly efficient, durable, and economically viable electrocatalysts for the hydrogen evolution reaction (HER) plays a crucial role in enabling large‐scale green hydrogen production. However, significant challenges remain in improving the efficiency of conventional catalytic processes. Here, we report osmium nanocluster‐decorated molybdenum boride (Os/MoB) as an efficient catalyst for the HER, operating via a novel hydrogen spillover mechanism. The Os/MoB catalyst achieves remarkably low overpotentials (η 10 = 22, 27, and 11 mV) to reach 10 mA cm −2 in alkaline, acidic, and alkaline seawater (1 m KOH + seawater) electrolytes, performance that matches or surpasses commercial Pt/C. Density functional theory (DFT) calculations reveal that H 2 O adsorbs on the MoB surface, followed by the dissociation of H 2 O, where the generated H* species spillover to the interfacial Os sites, subsequently recombining and releasing H 2 . Furthermore, an Os/MoB‐based anion exchange membrane water electrolyzer (AEMWE) delivers a current density of 500 mA cm −2 at low voltages of only 1.78 V in 1 m KOH and 1.88 V in alkaline seawater and maintains stable operation for over 100 h.
Yu et al. (2026) studied this question.