Ultra-economical fabrication of a Ru cluster-loaded Ni(OH)2 self-supported electrode via sub-hour corrosion for effective bifunctional water splitting

Abstract

The limited availability and exorbitant expense of ruthenium (Ru) impede its widespread utilization in electrocatalysts for water splitting. Herein, an ultra-economical self-supported Ru–Ni(OH)₂ catalyst was synthesized via sub-hour spontaneous corrosion, exploiting the inherent reduction potential difference between Ru and Ni. The characterization of microstructural features and atomic valence states demonstrated that incorporating Ru during the corrosion initiated a redox reaction, facilitating electron transfer. This optimized electron distribution promoted O* adsorption during the oxygen evolution reaction (OER) and augmented H⁺ utilization in the Heyrovsky step of the hydrogen evolution reaction (HER), thereby accelerating reaction kinetics. In 1.0 M KOH, the Ru–Ni(OH)₂ catalyst exhibited remarkable catalytic activity. It achieved an overpotential of 231.91 mV at 10 mA cm⁻² for the OER and 51.15 mV at 10 mA cm⁻² for the HER, accompanied by rapid kinetics and robust stability. Ru–Ni(OH)₂, functioning as a bifunctional electrode, achieved a cell voltage of 1.51 V at 10 mA cm⁻² during overall water splitting. When incorporated into an AEM electrolyzer, within a high-temperature electrolyte maintained at 60 °C and with the electrode sheet heated to 80 °C, it exhibited 1.75 V at 0.1 A cm⁻². Upon estimation, Ru–Ni(OH)₂ synthesized within less than one hour exhibited exceptional economic viability at a cost of approximately 0.12 $ cm⁻², representing an 86.58% cost reduction and 97.45% process acceleration compared to previously reported Ru-based catalysts. This study presented an ultra-economical Ru–Ni(OH)₂ electrocatalyst synthesized within sub-hour cycles, demonstrating high-efficiency catalytic performance. It is expected to resolve the cost-related application bottleneck plaguing Ru-based electrocatalysts.