An IrRu alloy nanocactus on Cu_2-xS@IrS_y as a highly efficient bifunctional electrocatalyst toward overall water splitting in acidic electrolytes

Development of highly active and durable bifunctional electrocatalysts for overall water splitting is vital for the economical production of H₂ as an alternative energy source. Herein, we report the synthesis of Cu_2-xS@IrS_y@IrRu nanoparticles (CIS@IrRu NPs), which show excellent catalytic performances for both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in an acidic electrolyte. Benefiting from the optimal composition of IrRu and the stable IrS_y shell, the cactus-like IrRu NPs show high electrocatalytic activity and stability. The cactus-like IrRu NPs exhibit optimal HER and OER performances and high stability at a ratio of Ir/Ru 1.00:1.07. In overall water splitting, the CIS@Ir₄₈Ru₅₂ NPs achieve a current density of 10 mA cm^-2 at a cell voltage of only 1.47 V in 0.1 M HClO₄ electrolyte and show negligible degradation after 100 h of continuous operation in the stability test.