Thermal evaporation-driven fabrication of Ru/RuO 2 nanoparticles onto nickel foam for efficient overall water splitting.

Developing high-performance bifunctional electrocatalysts towards the hydrogen evolution reaction/oxygen evolution reaction (HER/OER) holds great significance for efficient water splitting. This work presents a two-stage metal-organic thermal evaporation strategy for the fabrication of Ru-based catalysts (Ru/NF) through growing ruthenium (Ru)/ruthenium dioxide (RuO 2 ) nanoparticles (NPs) on nickel foam (NF). The optimal Ru/NF shows remarkable performance in both the HER (26.1 mV) and the OER (235.4 mV) at 10 mA cm -2 in an alkaline medium. The superior OER performance can be attributed to the synergistic interaction between Ru and RuO 2 , facilitating fast alkaline water splitting. Density functional theory studies reveal that the resulting Ru/RuO 2 with the (110) crystal surface reinforces the adsorption of oxygen on RuO 2 , while metallic Ru improves water dissociation in alkaline electrolytes. Besides, Ru/NF requires only 1.50 V at 10 mA cm -2 for overall water splitting, surpassing 20 wt% Pt/C/NF||RuO 2 /NF. This work demonstrates the promising potential of a thermal evaporation approach for designing stable Ru-based nanomaterials loaded onto conductive substrates for high performance overall water splitting.