A highly active and stable IrO <i> _x </i> /SrIrO ₃ catalyst for the oxygen evolution reaction

TLDR

Oxygen electrochemistry is vital for renewable energy devices, yet the sluggish OER kinetics constrain their performance and commercialization. During electrochemical testing, strontium leaching from SrIrO₃ thin films generates an IrOx/SrIrO₃ catalyst, and DFT calculations indicate that the resulting surface layers contain highly active IrO₃ or anatase IrO₂ motifs. The IrOx/SrIrO₃ catalyst delivers a specific activity of 10 mA cm⁻² with only 270–290 mV overpotential for 30 h in acid, outperforming existing IrOx and RuOx OER catalysts.

Abstract

Oxygen electrochemistry plays a key role in renewable energy technologies such as fuel cells and electrolyzers, but the slow kinetics of the oxygen evolution reaction (OER) limit the performance and commercialization of such devices. Here we report an iridium oxide/strontium iridium oxide (IrO x /SrIrO 3 ) catalyst formed during electrochemical testing by strontium leaching from surface layers of thin films of SrIrO 3 . This catalyst has demonstrated specific activity at 10 milliamps per square centimeter of oxide catalyst (OER current normalized to catalyst surface area), with only 270 to 290 millivolts of overpotential for 30 hours of continuous testing in acidic electrolyte. Density functional theory calculations suggest the formation of highly active surface layers during strontium leaching with IrO 3 or anatase IrO 2 motifs. The IrO x /SrIrO 3 catalyst outperforms known IrO x and ruthenium oxide (RuO x ) systems, the only other OER catalysts that have reasonable activity in acidic electrolyte.