Tuning on Highly Dispersed Iridium on Antimony-Doped Tin Oxide with Strong Metal–Support Interaction for Oxygen Evolution Reaction

Abstract

In the present study, we used a simple and efficient microwave-assisted NaBH₄ reduction method to generate unsupported and antimony-doped tin oxide (ATO)-supported metallic iridium nanoparticles (Ir-NPs). The effects of pretreatment on the support and iridium precursor oxidation state in two different salts (IrCl₃·nH₂O and (NH₄)₂IrCl₆) were investigated to produce efficient and stable electrocatalysts for oxygen evolution reaction (OER) in acidic electrolysis. Electrocatalysts with an Ir loading of 40 wt % supported on pristine ATO and acid-treated ATO were synthesized, and the performance was compared with the unsupported, synthesized, and commercial electrocatalysts. The Ir-NPs loaded on the support surface with 98% reaction yield and narrow size distribution, while without the support, somewhat agglomerated Ir-NPs were generated. A strong metal–support electron interaction at the junction of the Ir support, promoting the electrocatalyst stability and activity, was achieved for the supported electrocatalysts obtained from both precursors. The best electrocatalyst has demonstrated an excellent OER activity of 597 A g_Ir^–1 compared to that of 305 A g_Ir^–1 for a commercial IrO₂ benchmark and a high potentiodynamic accelerated stress test stability (OER activity retention: 76% compared to 31% for commercial IrO₂). The superior electrochemical performance can be attributed to the prereaction strong adsorption of the iridium precursor on the support surface, resulting in postreaction highly dispersed small NPs over the support surface generating strong metal–support interaction at the junction of Ir-ATO.AT.