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One of the primary challenges for proton exchange membrane (PEM) electrolyzers is the sluggish kinetics of the oxygen evolution reaction (OER) at the anode, which requires the use of precious metals or metal oxides, such as iridium (Ir) or iridium oxide (IrO_x), as the OER catalyst. This study introduces a one-pot surfactant-free polyol reduction method to disperse iridium nanoparticles on a tungsten doped titanium oxide (W_xTi_1-xO₂) support. The polyol reduction approach for the Ir/W_xTi_1-xO₂ catalyst synthesis was systematically investigated to determine the influence of synthesis parameters on the catalysts’ physical properties, and its electrochemical activity and durability. The most promisingmore » synthesized catalyst with 38 wt% Ir (Ir_38%/W_xTi_1-xO₂) demonstrated five times higher mass activity than an Ir-black baseline (the industry standard catalyst) based on rotating-disk electrode (RDE) studies. When tested in a real water electrolyzer system, the synthesized catalyst enabled the Ir loading to be lowered by an order of magnitude while retaining a similar electrolyzer performance found for the baseline Ir-black catalyst. In conclusion, the Ir_38%/W_xTi_1-xO₂ catalyst also demonstrated remarkable stability, e.g., only small voltage (<20 mV) increase was observed during a 1200-hour durability test at a constant current density of 1500 mA/cm².« less

Unsupported iridium (Ir) nanoparticles, that serve as standard oxygen evolution reaction (OER) catalysts in acidic electrolyzers, were investigated for electrochemical performance and durability in rotating disk electrode (RDE) half-cells. Fixed potential holds and potential cycling were applied to probe the durability of Ir nanoparticles, and performance losses were found to be driven by particle growth (coarsening) at moderate potential (1.4 to 1.6 V) and Ir dissolution at higher potential (>/=1.8 V). Several different commercially available samples were evaluated and standardized conditions for performance comparison are reported. In conclusion, the electrocatalyst RDE results have also been compared to results obtained formore » performance and durability in electrolysis cells.« less