Dataset to accompany publication "Shell-Thickness Optimization of TiO2@IrO2 Core-Shell Catalyst for Proton Exchange Membrane Water Electrolysis"

The scarcity of iridium currently hampers the widespread implementation of proton exchange membrane water electrolysis (PEMWE). Reducing the iridium loading is essential, and catalysts with a low iridium content are a viable approach to reach this goal. This study investigates a series of TiO₂@IrO₂ core-shell catalysts with three different TiO₂ support-particle sizes (3, 14, and 56 m² g^‑1) and three different iridium oxide contents (30, 50, and 70 wt%). We demonstrate that, for optimal iridium utilization, the IrO₂ shell thickness should be maximized, which is readily achieved by employing low-surface area supports. Following this strategy, a TiO₂@IrO₂ core-shell catalyst with 50 wt% IrO₂ is designed, whose single-cell performance outperforms a commercial reference catalyst (88 wt% IrO₂) by 43 mV at 2 A cm^‑2 at a low iridium loading of 0.1 mg_Ir cm^-2. This improvement of the core-shell catalyst is ascribed to a thicker CL that is less prone to disconnection effects. Furthermore, we investigate how accurately our catalyst pre-testing can predict the performance of a single-cell electrolyzer. Interestingly, a strong correlation between powder conductivity and single-cell high-frequency resistance (HFR) is observed, underlining the importance of catalyst conductivity when using titanium porous transport layers (PTLs) without noble metal coating.