Active, Simple Iridium–Copper Hydrous Oxide Electrocatalysts for Water Oxidation

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  • A series of Ir1–xCux (x = 0–0.5) hydrous oxide nanoparticles (HO-np) were prepared simply by stirring solutions of IrCl3 hydrate and CuCl2 hydrate in aqueous KOH under air. Their water oxidation activities were measured in 0.1 M HClO4. The Ir0.89Cu0.11 HO-np was the most active catalyst in the series with mass (Ir) – normalized activity = 142 A gIr–1 and electrochemically accessible Ir sites normalized activity >180 A mmolIr–1 (both at 250 mV overpotential). The Ir0.89Cu0.11 HO-nps were stable for 24 h galvanostatic oxidations at 1 mA cm–2geometric, with only 280 mV overpotential. The average diameter of the Ir0.89Cu0.11 HO-nps was ∼1.30 nm. XPS results suggested that doping with Cu2+ reduces the overall charge in the lattice, resulting in higher electron density at Ir than in pure Ir HO-np. Preliminary mechanistic investigations showed that the activity enhancement by Cu is not only a surface area effect, and the presence of Cu does not appear to significantly alter the mechanism of the water oxidation reaction.

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    Attribution-NonCommercial 4.0 International