Amorphous nickel hydroxide confined noble metal single atoms for enhanced alkaline hydrogen evolution reaction

The dynamic regulation of the local atomic environment under operational conditions represents a frontier in the development of single-atom catalysts (SACs) for the alkaline hydrogen evolution reaction (HER). Here, we report a strategy that harnesses in-situ electrochemical reconstruction to construct a functional confinement structure for single atoms. Using Ru-doped NiP x as a precursor, we guide its surface under HER conditions to form an reconstructed amorphous Ni(OH) 2 layer which acts as a robust host to confine and stabilize Ru single atoms. The reconstructed Ru-NiP x (OH) y catalyst delivers an extremely low overpotential of 9 mV at 10 mA/cm 2 and maintains stable operation for over 1000 h. Comprehensive characterization—combining vacuum-interconnected X-ray photoelectron spectroscopy and in-situ Raman spectroscopy—reveals that this confining amorphous layer not only modulates the electronic structure of Ru but also accelerates water dissociation and proton transport, thereby generating a local acid-like environment around the active sites. This synergy between atomic confinement and microenvironment engineering profoundly optimizes the overall HER kinetics. Furthermore, similar improvements are observed when Pt or Ir single atoms are introduced, demonstrating the universality of this reconstruction-driven activation strategy. This work establishes a paradigm for activating SACs by programming reconstruction to build integrated architectures where confinement and tailored microenvironments cooperate to boost catalytic performance.