Iridium Oxide Catalyst Supported on Antimony-Doped Tin Oxide for High Oxygen Evolution Reaction Activity in Acidic Media

Lowering of the oxygen evolution reaction (OER) noble metal catalyst loading on the anode of a polymer electrolyte membrane water electrolysis (PEMWE) is a necessity for enabling the large-scale hydrogen production based on this technology. This study introduces a remarkably active OER catalyst that is based on the dispersion of Ir nanoparticles on a highly conductive oxide support. The catalyst was designed in a way to combine all characteristics that have been reported to enhance the OER activity on an Ir oxide-based catalyst, including high catalyst dispersion and controlling the Ir catalyst particle size, so that this design approach provides both high surface area to Ir mass ratio and at the same time ensures maximum synergetic interaction with the oxide support, termed strong metal–support interaction (SMSI). This was achieved through using a high surface area (50 m2/g) and highly conductive antimony-doped tin oxide support (2 S/cm), where combining a high catalyst dispersion and maximum SMSI resulted in a very high OER activity of the Ir/ATO catalyst (≈1100 A/gIr, at 80 °C and 1.45 VRHE). This enhanced activity will allow a significant reduction (ca. 75-fold) in the precious metal catalyst loading when this catalyst is implemented in the anode of a PEMWE.