Reducing iridium (Ir) usage is essential for the commercial viability of proton exchange membrane water electrolysis (PEMWE), where the oxygen evolution reaction (OER) is a major performance and cost bottleneck. Conventional Ir nanoparticles (∼5 nm) suffer from low dispersion and limited surface utilization. Here, we report a catalyst architecture comprising ultrathin Ir nanosheets (Ir NS) supported on spherical TiO2 particles (Ir NS/TiO2). The ∼100 nm TiO2 particles effectively disperses 1-3 μm-wide, sub 2 nm-thick Ir nanosheets, ensuring full surface exposure and continuous electron transport, despite the intrinsically low conductivity of TiO2. The Ir NS/TiO2 catalyst exhibits enhanced OER activity and durability in both half-cell and PEMWE single-cell configurations. At an Ir loading of 0.7 mgIr cm-2, Ir NS/TiO2 achieves 3.6 A cm-2 at 1.8 V, significantly outperforming commercial Ir nanoparticles (Ir NP, 2.6 A cm-2). Long-term operation at 1.0 A cm-2 over 1000 h shows a low voltage decay rate of 0.095 mV h-1, compared to 0.414 mV h-1 for Ir NP. Moreover, Ir NS/TiO2 with an Ir loading amount of 0.5 mgIr cm-2 delivers comparable performance to Ir NP at 1.4 mgIr cm-2. These results present Ir NS/TiO2 as a highly efficient and durable OER catalyst, supporting its potential for cost-effective, scalable green hydrogen production.
Shin et al. (Wed,) studied this question.
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