Synergistic Ru nanoparticles and metal vacancies in NiFe-layered double hydroxides for enhanced oxygen evolution reaction

Electrocatalytic water splitting powered by renewable energy holds great promise for hydrogen production, but its overall performance is largely hindered by the sluggish kinetics of oxygen evolution reaction (OER). Herein, we report that a rationally-designed NiFe layered double hydroxides (LDHs) electrocatalyst, endowed with synergistic Ru nanoparticles (NPs) and metal vacancies (denoted as Ru/V M -NiFe-LDHs), exhibits highly efficient OER performance in alkaline electrolyte. As evidenced by X-ray absorption fine structure (XAFS) spectroscopy, the presence of mixed Ni/Fe vacancies is verified by their reduced coordination numbers. The co-introduction of Ru NPs and metal vacancies synergistically optimizes the surface electronic structure and promotes charge transfer kinetics, thereby leading to the dual-modified catalyst that delivers an ultralow overpotential of 192.8 mV at 10 mA cm −2 with a small Tafel slope of 57.8 mV dec −1 and exhibits exceptional long-term stability. In combination of in situ Raman spectroscopy and computational calculations, it is revealed that the derived β-NiOOH works as the catalytically active phase under operational conditions, while Ru sites effectively lower the energy barrier of the rate-determining step of OER process. This work establishes a generalizable design strategy for high-performance LDHs-based electrocatalysts by harnessing the cooperative interplay between noble-metal nanoparticles and defect engineering.