Atomically dispersed hexavalent iridium oxide from MnO2 reduction for oxygen evolution catalysis

Hexavalent iridium (IrVI) oxide is predicted to be more active and stable
than any other Ir oxide for the oxygen evolution reaction in acid;
however, its experimental realization remains challenging. Here, we report
the synthesis, characterization, and application of atomically dispersed
IrVI oxide (IrVI-ado) for proton-exchange membrane (PEM) water
electrolysis. The IrVI-ado was synthesized by oxidatively substituting the
ligands of K2IrCl6 with manganese oxide. The mass-specific activity (1.7 ×
105 A gIr-1) and turnover number (1.5 × 108) exceeded those of benchmark
Ir oxides, and in-siu X-ray analysis during PEM operations manifested the
durability of IrVI at current densities up to 2.3 A cm-2. The high
activity and stability of IrVI-ado showcase its promise as an anode
material for PEM electrolysis.