Tailoring NiFe LDH with ruthenium doping for high-performance bifunctional electrocatalysis in conventional and environmental water splitting systems

Electrochemical water electrolysis stands as a viable route for hydrogen energy, yet its large-scale industrial deployment is hindered by the slow reaction kinetics of the anodic oxygen evolution reaction (OER) and the reliance on scarce noble metal catalysts. Herein, we present ruthenium-doped nickel–iron layered double hydroxide nanosheet arrays supported on nickel foam (Ru-NiFe LDH/NF) as a high-performance bifunctional electrocatalyst. The doping strategy realizes dual optimization through atomic-level electronic interactions: the electronegativity difference between Ru, Ni and Fe induces charge transfer, precisely regulating the free energy of OER intermediates adsorbed on Ni active sites while increasing oxygen vacancies; concurrently, Ru atoms themselves act as high-activity hydrogen evolution reaction (HER) sites, constructing a bifunctional structure of Ni&Ru active sites. In 1 M KOH, it necessitates overpotentials of just 249 mV for OER and 93 mV for HER at 10 mA cm −2 . The overall water splitting (OWS) system requires a total cell voltage of merely 1.57 V with Faraday efficiency close to 100% and exceptional stability. Furthermore, by replacing OER with the sulfide oxidation reaction (SOR), the cell voltage for OWS at 100 mA cm −2 decreases from 1.82 V to 1.52 V, achieving low-energy-consumption “sulfur-hydrogen” co-production. Impressively, the catalyst also maintains superior catalytic activity and prolonged stability in real seawater and even sulfide-containing seawater, demonstrating its immense prospect for practical-scale applications. This study presents a novel strategy to fabricate bifunctional catalysts and offers detailed experimental data for the coordinated development of low-energy-consumption hydrogen generation coupled with resource utilization of complex water bodies.