Rapid formation of Ru-O-Ni bridges on the nickel foam through continuous flow microreactor for efficient hydrogen evolution reaction

Abstract

Efficient water electrolysis in alkaline media represents a promising strategy for advancing renewable energy utilization through sustainable hydrogen production. Metal nanoparticle catalysts have garnered significant attention for hydrogen evolution reaction (HER) due to their superior catalytic efficiency. This work introduced a continuous flow reaction platform to rapidly and in-situ synthesize Ru-Ni(OH)₂ on nickel foam (NF) electrode through the spontaneous redox reaction for 1 h. The rapid renewal of the liquid-solid interface between solution and substrate facilitated the reaction process to generate Ru nanoparticles (NPs) across Ni(OH)₂ nanosheets (NSs). Ru NPs were anchored to Ni(OH)₂ NSs via Ru-O-Ni bridges on the NF surface, ensuring optimal exposure of active sites and enhanced structural stability. The charge transfer facilitated by Ru-O-Ni bridges dynamically modulated the electronic structure of the Ru-Ni(OH)₂ interface, accelerating the hydrogen evolution reaction kinetics. As results, Ru-Ni(OH)₂ catalyst demonstrated outstanding HER activity with low overpotentials of 19 and 77 mV at 10 and 100 mA·cm⁻² respectively, and a Tafel slope of 45.4 mV·dec⁻¹ in 1.0 M KOH, surpassing Ru/Ni(OH)₂ catalyst prepared by the classic immersion method in stirred reactor (35.3 and 140 mV at 10 and 100 mA·cm⁻², respectively) and commercial Pt/C catalyst (28.8 and 105 mV at 10 and 100 mA·cm⁻², respectively). Moreover, the prepared Ru-Ni(OH)₂ catalyst maintained excellent stability, enduring 5000 cyclic voltammetry cycles and 50 h at a current density of 50 mA·cm⁻². This innovative and facile continuous synthesis strategy provides a promising pathway for synthesizing high-performance HER catalysts.