Oxophilic gallium single atoms bridged ruthenium clusters for practical anion-exchange membrane electrolyzer.

The development of highly efficient and durable alkaline hydrogen evolution reaction (HER) catalysts is crucial for achieving high-performance practical anion exchange membrane water electrolyzer (AEMWE) at ampere-level current density. Herein, we report a design concept by employing Ga single atoms as an electronic bridge to stabilize the Ru clusters for boosting alkaline HER performance in practical AEMWE. Experimental and theoretical results collectively reveal that the bridged Ga sites trigger strong metal-support interaction for the homogeneous distribution of Ru clusters with high density, as well as optimize the Ru-H bond strength due to the electron transfer between Ru and Ga for enhanced intrinsic HER activity. Moreover, the oxophilic Ga sites near the Ru clusters tend to adsorb the hydroxyl species and accelerate the water dissociation for sufficient proton supplement in an alkaline medium. The Ru-Ga_SA/N-C catalyst exhibits a low overpotential of 4 ± 1 mV (10 mA cm^-2) and high mass activity of 9.3 ± 0.5 A mg^-1_Ru at -0.05 V vs RHE. In particular, the Ru-Ga_SA/N-C-based AEMWE in 1 M KOH delivers a voltage of only 1.74 V to reach an industrial current density of 1 A cm^-2, and can steadily operate at 1 A cm^-2 for more than 170 h.