Regulating Sub-1 nm Ru Clusters via Single-Atom Catalyst Support toward Efficient Anion Exchange Membrane Water Electrolysis

Anion exchange membrane water electrolysis (AEMWE) has emerged as a promising technology for producing green hydrogen. However, the hydrogen evolution reaction (HER) under alkaline conditions suffers from sluggish kinetics and insufficient stability. While Ru-based catalysts are attractive alternatives to Pt, they still encounter limitations including insufficient water dissociation, OH* poisoning, and inadequate structural stability at high current densities. Herein, we report an innovative and universal catalyst design strategy: utilizing a single-atom catalyst matrix (Co−N−C) as an anchoring and electronic-modulating substrate to stabilize sub-nanometer noble metal clusters, which achieves good alkaline HER performance. As a typical example, sub-1 nm Ru clusters anchored on a porous Co−N−C single-atom scaffold (Ru@Co−N−C) exhibit an ultralow overpotential of 15 mV at 10 mA cm−2, and high mass activity of 6.36 A mgRu−1 at an overpotential of 100 mV, representing a 2.99-fold increase over that over Ru@N−C and a 10.26-fold increase of that of commercial Pt/C. Importantly, the Ru@Co−N−C catalyst also demonstrates a robust durability of over 360 h. When applied in an AEMWE device, it can achieve an industrial-scale current density of 1 A cm−2 at 1.78 V, and a stability over 150 h under 1 A cm−2. In situ characterizations and DFT calculations demonstrate that the Co−N−C support stabilizes Ru clusters and modulates their electronic structure to enhance water dissociation and facilitate OH* desorption, collectively improving the HER performance of the Ru clusters. This work offers a feasible and universal strategy for designing high-performance alkaline HER catalysts for AEMWE.