Ruthenium-Integrated Nickel Selenide Nanoparticles for Efficient Multifunctional Electrocatalysis

The exploration of a highly active and durable catalyst for the electrocatalytic hydrazine oxidation reaction (HzOR), assisted seawater splitting, is crucial for long-term hydrogen generation. Nickel-based materials offer tremendous potential due to their excellent electrical conductivity and catalytic activity. However, significant potential for improvement remains, highlighting opportunities for strategic improvement. Herein, we present a simple hydrothermal method to synthesize ruthenium-integrated nickel selenide (Ru-NiSe) nanoparticles for HzOR-assisted seawater splitting. The spectroscopic characterization validates the effective integration of Ru3+ without affecting the nickel selenide structure. Additionally, Ru3+ integration induces a modification in the electronic structure of NiSe, optimizing the binding energy of the reactive intermediates. The Ru-NiSe exhibited superior catalytic activity, achieving 100 mA cm–2 at a potential of 0.70 V vs RHE for HzOR and 1.57 V vs RHE for the oxygen evolution reaction (OER) in freshwater, whereas NiSe required a higher potential to reach the same current density. In seawater, Ru-NiSe shows exceptional performance, delivering 100 mA cm–2 at a potential of 0.80 V vs RHE for HzOR and 1.62 V vs RHE for OER, respectively. When used in a two-electrode setup, Ru-NiSe efficiently replaced the sluggish OER with HzOR, resulting in a reduction of 0.78 V cell voltage at a 50 mA cm–2 current density in seawater. Notably, Ru-NiSe showed better activity in seawater compared to freshwater in the two-electrode system. The Ru-NiSe demonstrated the stability of 4 days for HzOR-assisted seawater splitting in a two-electrode system. Moreover, the H2 production efficiency of Ru-NiSe during HzOR was also enhanced by 1.8 times compared to the OER in seawater splitting. The Ru-NiSe catalyst demonstrated energy efficiency by approximately 72% when OER was substituted with HzOR.