P-Block Ga-Induced Interfacial Water Optimization on Ru Nanosheets for Anion Exchange Membrane Water Electrolysis

The development of highly active and durable electrocatalysts for the alkaline hydrogen evolution reaction (HER) is essential for advancing sustainable hydrogen production through anion exchange membrane water electrolysis (AEMWE). In this work, we report the one-pot solvothermal synthesis of Ga-doped Ru nanosheets (RuGa NSs) as a high-performance alkaline HER catalyst, where Ga incorporation is shown to optimize the interfacial water structure to enhance catalytic activity. The optimized RuGa NSs exhibit outstanding alkaline HER performance, requiring a low overpotential of only 18 mV at 10 mA cm^-2, coupled with a small Tafel slope of 37.2 mV dec^-1. When integrated into an AEMWE device, the RuGa NSs||NiFe-LDH-based AEMWE enables a low cell voltage of 1.74 V to deliver 1.0 A cm^-2 in 1.0 M KOH at 60 °C. Moreover, the AEMWE device shows exceptional long-term stability, operating continuously for 200 h at 0.5 A cm^-2 with a minimal voltage decay of 5.5%. Operando Raman spectroscopy results demonstrate that Ga doping promotes the dynamic transformation of rigid, hydrogen-bonded water into more mobile free-water molecules. This restructuring creates a favorable local reaction environment by increasing the flexibility of the hydrogen-bond network, thereby facilitating water dissociation and proton transfer.