Hydrolysis synthesis of iridium oxide ▫$(IrO_x)$▫ on carbon for acidic oxygen evolutionKarade, Swapnil Sanjay (Avtor) Sharma, Raghunandan (Avtor) Gyergyek, Sašo (Avtor) Morgen, Per (Avtor) Pilgaard Andersen, Bettina (Avtor) Aaskov Karlsen, Martin (Avtor) Ravnsbæk, Dorthe (Avtor) Andersen, Shuang Ma (Avtor) iridium oxideoxygen evolution reactioncarbon supportstabilityThe development of efficient and durable oxygen evolution reaction (OER) electrocatalysts is critical for advancing proton exchange membrane water electrolyzers (PEMWEs). This study presents a nanostructured iridium oxide anchored on high-surface-area carbon (IrOx/C) OER electrocatalyst, synthesized through ultrasonication-assisted deposition of hydrolysis-derived colloidal IrOx nanoparticles onto the carbon support. The as-prepared IrOx/C exhibits a mass activity exceeding five times that of unsupported benchmark commercial IrO2, attributed to its uniform nanoparticle distribution and enhanced surface chemistry. Post-synthesis heat-treatments at two different temperatures (200 or 300 °C) were employed to stabilize the catalyst structure. Notably, the sample treated at 200 °C retained 84% of its initial activity after accelerated stress testing, outperforming the commercial counterpart, which retained 67 % under identical conditions. Comprehensive structural and morphological analyses revealed that the heat-treatment increased the IrOx particle size and decreased the Ir³⁺/Ir⁴⁺ ratio while leaving the amorphous nature of IrOx unaffected, which combinedly led to the improved durability. These findings offer valuable insights into designing stable low-iridium OER electrocatalysts for acidic PEMWE applications.Elsevier20262026-01-15 13:23:47Neznano25299Nizozemskasl© 2026 The Author(s).