Nanorod Structuring of IrOx on a Unique Microstructure of Sb-Doped Tin Oxide to Dramatically Boost the Oxygen Evolution Reaction Activity for PEM Water Electrolysis

Proton exchange membrane water electrolysis (PEMWE) is being actively developed as a promising technology to produce high-purity hydrogen. While PEMWE has been commercialized, a serious roadblock for wider deployment is the high cost associated with the use of high loadings of the noble metal Ir-based anode catalysts for the oxygen evolution reaction (OER). To lower the Ir loading amount, it is critically important to develop efficient catalysts with increased Ir utilization and higher OER activity. Herein, we report the preparation of one-dimensional Ir oxide nanorod catalysts supported on Sb-doped SnO2 and demonstrate their extremely high activity in the OER catalysis, with the Ir mass-specific activity being 10 times higher than that of commercial IrOx catalyst at 1.5 V vs reversible hydrogen electrode (RHE), showing great promise in dramatically reducing the Ir loading in PEMWE cells. The experiment also found that the OER activation energy was greatly reduced for the Ir oxide nanorod/Sb-SnO2 catalyst. It was proposed, based on experimental results and density functional theory (DFT) calculations, that the nanorod geometry and the interaction with SnO2 support rendered a surface with a lower degree of Ir oxidation, which allows the surface terminal oxygens to be closer together while allowing facile desorption of oxygenated species, which could play an important role in facilitating the crucial step of the OER, thereby enhancing the OER activity.