Extraordinary acidic oxygen evolution on new phase 3R-iridium oxide

Abstract

<h2>Summary</h2> Electrochemical water splitting provides a green pathway for hydrogen generation, while iridium oxide (IrO₂) is almost the only stable anode catalyst for acidic media. Yet, it is still a huge challenge to develop an efficient IrO₂ catalyst. Here, we demonstrate a microwave-assisted mechano-thermal method that achieves a new 3R phase IrO₂. This 3R-IrO₂ achieves an ultralow overpotential of 188 mV at the current density of 10 mA cm_geo⁻² and a notably high turnover frequency of 5.7 s_UPD⁻¹ at 1.50 V versus reversible hydrogen electrode. It also endures limited decay under the current density of 10 mA cm_geo⁻² for 511 h prolong test in acidic electrolyte. The new active sites of the edge-sharing structure in 3R-IrO₂ and the fast proton transportation along interlayers and intralayers through iridium vacancies contribute to the extraordinary acidic oxygen evolution reaction (OER) activity and stability. This work highlights the great potential of new metastable materials toward advanced electrocatalysis.