Atomically dispersed hexavalent iridium oxide from MnO<sub>2</sub> reduction for oxygen evolution catalysis.
basic_science · Level V
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- Record sourced from PubMed, PMID 38723092.
- Also identified by DOI 10.1126/science.adg5193.
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Abstract
Hexavalent iridium (Ir<sup>VI</sup>) oxide is predicted to be more active and stable than any other iridium oxide for the oxygen evolution reaction in acid; however, its experimental realization remains challenging. In this work, we report the synthesis, characterization, and application of atomically dispersed Ir<sup>VI</sup> oxide (Ir<sup>VI</sup>-<i>ado</i>) for proton exchange membrane (PEM) water electrolysis. The Ir<sup>VI</sup>-<i>ado</i> was synthesized by oxidatively substituting the ligands of potassium hexachloroiridate(IV) (K<sub>2</sub>IrCl<sub>6</sub>) with manganese oxide (MnO<sub>2</sub>). The mass-specific activity (1.7 × 10<sup>5</sup> amperes per gram of iridium) and turnover number (1.5 × 10<sup>8</sup>) exceeded those of benchmark iridium oxides, and in situ x-ray analysis during PEM operations manifested the durability of Ir<sup>VI</sup> at current densities up to 2.3 amperes per square centimeter. The high activity and stability of Ir<sup>VI</sup>-<i>ado</i> showcase its promise as an anode material for PEM electrolysis.