Iridium Oxide Shell Structure on Rutile Titanium Oxide for Efficient Supported Catalyst for the Oxygen Evolution Reaction.

Proton exchange membrane water electrolysis is a promising technology for the production of hydrogen via water electrolysis. Lower amounts of iridium oxide are needed at the anode to reduce the cost and precious metal dependence of this technology for large-scale development. The use of iridium oxide catalysts supported on non-precious supports can help reduce the required iridium loading. This work presents a novel core-shell structure in which a thin layer of IrO₂ is grown on rutile TiO₂ spheres. The structural compatibility between rutile IrO₂ and rutile TiO₂ enables the formation of a continuous IrO₂ shell, unlike on anatase-rich TiO₂ supports, where only a decorated structure is observed. The core-shell architecture and homogenous IrO₂ distribution on the rutile support is confirmed by imaging, diffraction, and spectroscopy. Electrochemical evaluation demonstrates superior mass activity and pseudo-capacitance for the core-shell material (on rutile) than for the decorated structure (on anatase). The core-shell supported material as electrochemical performance similar to a commercial unsupported IrO₂ catalyst. These results highlight the potential of the rutile IrO-rutile TiO interaction for improving catalyst utilization. Such core-shell materials are promising candidates for an integration in low-loading systems where unsupported materials suffer in-plane conductivity losses.