Strickler, Alaina L. Higgins, Drew Jaramillo, Thomas F. Crystalline Strontium Iridate Particle Catalysts for Enhanced Oxygen Evolution in Acid Iridium-based mixed metal oxide phases have been shown as promising electrocatalysts for the oxygen evolution reaction (OER) because of their ability to stabilize unique Ir-based surface sites with modulated properties and improved activity. Herein, the effect of crystal structure on the OER activity of Sr iridate particles is explored. Phase-pure Sr<sub>4</sub>IrO<sub>6</sub>, Sr<sub>2</sub>IrO<sub>4</sub>, and SrIrO<sub>3</sub> micrometer-scale particles show high activity toward the OER with the electrode area-based geometric activity increasing in the order of IrO<sub><i>x</i></sub> < SrIrO<sub>3</sub> < Sr<sub>4</sub>IrO<sub>6</sub> < Sr<sub>2</sub>IrO<sub>4</sub> at a constant Ir mass electrode loading. Particularly, Sr<sub>2</sub>IrO<sub>4</sub> displays superior activity and stability compared to commercial Ir/C (Premetek) nanoparticles, including more than an order of magnitude improvement in the catalyst surface area normalized specific activity. This translated to a similar Ir-based mass activity for Sr<sub>2</sub>IrO<sub>4</sub> despite significantly larger average particles sizes (0.1–3 μm for Sr<sub>2</sub>IrO<sub>4</sub> versus 2–3 nm for Ir/C) and a 40-fold improvement in Ir-based mass activity in comparison to IrO<sub><i>x</i></sub> particles synthesized by a similar thermochemical procedure. During electrochemical testing of the Sr iridate materials, initial Sr leaching results in the formation of a stable Ir-rich catalyst surface with a modified electronic environment compared to Ir-only materials, potentially leading to enhanced OER activity. The superior intrinsic activity of Sr iridates illustrates the ability of surface-leached crystalline materials to stabilize high activity surface sites capable of significantly improving catalyst performance toward economical OER-based technologies. Ir-based mass activity;Sr 2 IrO 4;Crystalline Strontium Iridate Particle Catalysts;Sr iridate particles;Sr iridate materials;Sr 4 IrO 6;Sr leaching results;Ir-based surface sites;oxygen evolution reaction;Sr 2 IrO 4 displays;activity surface sites;catalyst surface area;IrO x particles;OER activity;Ir mass electrode loading;SrIrO 3 micrometer-scale particles show;Phase-pure Sr 4 IrO 6;Ir-rich catalyst surface;Enhanced Oxygen Evolution;metal oxide phases 2019-07-23
    https://acs.figshare.com/articles/journal_contribution/Crystalline_Strontium_Iridate_Particle_Catalysts_for_Enhanced_Oxygen_Evolution_in_Acid/8982719
10.1021/acsaem.9b00658.s001