Tailored design of engineered Os-SA/NiCu single-atom alloys for sustainable anion exchange membrane water electrolysis

A single-atom alloy with isolated Os in NiCu was constructed. • Os promotes water dissociation on Ni sites and optimizes hydrogen binding. • Reconfiguration of interfacial water yields a free-water-rich environment. • The catalyst delivers excellent performance and durability in an AEMWE device. Developing efficient and durable alkaline hydrogen evolution reaction (HER) catalysts is essential for sustainable hydrogen production via anion-exchange membrane water electrolysis (AEMWE) yet remains challenging. Herein, we report a single-atom alloy catalyst comprising atomically dispersed Os on the NiCu alloy array support (Os SA/NiCu), where the unique coordination environment engenders strong electronic interactions that synergistically enhance catalytic activity. The optimized catalyst achieves an overpotential of only 14 mV at 10 mA cm −2 and operates stably for over 2000 h at 200 mA cm −2 . Combined in situ spectroscopy and theoretical calculations reveal that the Os incorporation facilitates water dissociation on adjacent Ni sites, optimizes hydrogen binding energetics, and reconstructs the local interfacial water structure, thereby accelerating alkaline HER kinetics. When employed as the cathode in an AEMWE device, Os SA/NiCu delivers a cell voltage of 1.76  V at an industrial-relevant current density of 1 A cm −2 at 80 °C, with exceptional stability exceeding 500 h. This work establishes single-atom alloy engineering as an effective strategy to enhance noble metal utilization and intrinsic activity toward durable AEMWE systems. A single-atom alloy catalyst comprising atomically dispersed Os on a NiCu alloy array support was synthesized. In situ spectroscopy and DFT reveal that Os incorporation accelerates alkaline HER by synergistically modulating water dissociation, hydrogen binding, and interfacial water structure. Consequently, the catalyst achieves 1 A cm −2 at 1.76 V and operates stably at 0.5 A cm −2 for 1000 h in an AEMWE device. Download: Download high-res image (127KB) Download: Download full-size image