Investigating the Influence of Amorphous/Crystalline Interfaces on the Stability of IrO<sub>2</sub> for the Oxygen Evolution Reaction in Acidic Electrolyte
Thi Hong Nga Ngo, Jonathan Love, Anthony P. O’Mullane
Abstract
Abstract A major challenge with water splitting technology is to develop highly active and stable electrocatalysts for the oxygen evolution reaction (OER). IrO 2 – based electrocatalysts are one of the most active electrocatalysts for proton exchange membrane (PEM) electrolysers, due to their excellent activity for the OER in acidic conditions. However, IrO 2 often suffers from dissolution during electrolysis due to phase transitions into more soluble forms. Herein, a range of electrodeposited IrO 2 films annealed to different temperatures of up to 500 ° C are prepared to understand the influence that crystalline/amorphous interfaces have on performance during accelerated degradation tests in concentrated acidic solutions. This study showed that an IrO 2 film annealed at 300 °C exhibited the highest catalytic activity with a low overpotential of 150 mV at 10 mA cm −2 , the smallest Tafel slope of 51 mV dec −1 , with a less progressive decay in activity over a period of 8 h of accelerated degradation testing. This contrasts with both fully amorphous or more crystalline IrO 2 films that decayed much more rapidly within 1 h of testing indicating the role that amorphous/crystalline regions have on OER performance.