Discontinuously covered IrO2–RuO2@Ru electrocatalysts for the oxygen evolution reaction: how high activity and long-term durability can be simultaneously realized in the synergistic and hybrid nano-structure

Abstract

Here, we present our effort in simultaneously enhancing the intrinsic activity and improving the durability of catalysts based on Ir and Ru oxides. Through successful design and fabrication of the discontinuously covered IrO₂–RuO₂@Ru (3 : 1) supported structure, we are able to combine the high activity of RuO₂ and the outstanding stability of IrO₂. Specifically, the overpotential of the IrO₂–RuO₂@Ru (3 : 1) catalyst at 10 mA cm⁻² is only 281 mV, and the turnover frequency (TOF) values of IrO₂–RuO₂@Ru (3 : 1), Ir₃RuO₂ and IrO₂ catalysts are ca. 0.039, 0.023 and 0.017 s⁻¹ at 1.55 V, respectively, indicating that IrO₂–RuO₂@Ru (3 : 1) exhibits higher intrinsic activity and the active surface sites possess greater ability to generate oxygen. The excellent durability of the IrO₂–RuO₂@Ru (3 : 1) catalyst is confirmed with the overpotential at 10 mA cm⁻² positively shifting by only 16 mV after 3000 cycles through accelerated durability tests. Remarkably, the IrO₂–RuO₂@Ru (3 : 1) catalyst exhibits a huge advantage in reducing the use of precious metals in water electrolysis. Hence, the supported iridium–ruthenium bimetallic oxides show huge potential towards an active and stable application for the oxygen evolution reaction in acidic media.