IrO2 coated TiO2 core-shell microparticles advance performance of low loading proton exchange membrane water electrolyzers

[Display omitted] •A novel, scalable synthesis for IrO2@TiO2 core-shell microparticles based on electrostatic interaction of Ir-precursor and TiO2 particles.•High catalyst-dispersed electrodes achieved by directly coating the IrO2@TiO2 catalyst on titanium porous transport layers.•IrO2@TiO2 catalyst enabled a high performance of proton exchange membrane water electrolyzers (PEMWEs) with low Ir-loading of 0.4 mg cm−2.•PEMWEs using IrO2@TiO2 catalyst outperformed both unsupported IrO2 and supported IrO2/TiO2 commercial benchmark catalysts. Herein we present novel IrO2 coated TiO2 core-shell microparticles (IrO2@TiO2) as an oxygen evolution reaction catalyst. We compare the IrO2@TiO2 catalyst to commercial TiO2 supported IrO2 catalyst (IrO2/TiO2) and pure IrO2 catalyst powder. A stability analysis via on-line inductively coupled plasma mass spectrometry based on the S-number, a descriptor considering both energy efficiency and catalyst utilization efficiency, shows that the IrO2@TiO2 catalyst shows high potential for practical applications. This was further confirmed by full-cell tests showing superior performance of the IrO2@TiO2 catalyst with moderate and low loadings of 1.2 mgIr cm−2 and 0.4 mgIr cm−2, respectively. The core-shell catalyst is synthesized via facile route suitable for large quantities. Moreover, stable inks from the synthesized catalyst powder make this system appealing for large scale manufacturing of cells. Given the facile synthesis route, high activity, and good stability, the IrO2@TiO2 catalyst is potentially suitable for industry proton exchange membrane water electrolysis application.