Ultrathin Iridium Nanosheets on Titanium Oxide for High-Efficiency and Durable Proton Exchange Membrane Water Electrolysis
Dongwon Shin, Sang Jae Lee, Junu Bak, JeongHan Roh, KwangHo Lee, HyunWoo Chang, Hyein Lee, Min Jun Kim, Hyunwoo Yang, Seonghyun Kim, Seungbum Hong, EunAe Cho
Abstract
High Resolution Image Download MS PowerPoint Slide 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 TiO 2 particles (Ir NS/TiO 2 ). The ∼100 nm TiO 2 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 TiO 2 . The Ir NS/TiO 2 catalyst exhibits enhanced OER activity and durability in both half-cell and PEMWE single-cell configurations. At an Ir loading of 0.7 mg Ir cm –2, Ir NS/TiO 2 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/TiO 2 with an Ir loading amount of 0.5 mg Ir cm –2 delivers comparable performance to Ir NP at 1.4 mg Ir cm –2 . These results present Ir NS/TiO 2 as a highly efficient and durable OER catalyst, supporting its potential for cost-effective, scalable green hydrogen production.