Influence of IrO₂/TiO₂ coated titanium porous transport layer on the performance of PEM water electrolysis

Porous transport layer(PTL) plays an important role in the electron and mass transport of the polymer electrolyte membrane(PEM) water electrolyzer. Through harsh conditions of long-term operation, acidic environment, high operating temperature, the forming of TiO₂ on the surface of the Ti-PTL results in the PTL surface passivation. In this study, by combining two methods: spray-coating and thermal treatment, a thin layer of IrO₂/TiO₂ catalyst is deposited on the surface of the Ti-PTL to prevent the passivation and improve the performance of the PEM electrolyzer. The IrO₂/TiO₂ catalyst layer is expected to reduce the cell Ohmic resistance and improve the stability of the Ti-PTL due to preventing TiO₂ formation. By controlling the synthesis process, 5 samples with different Ir loading (0 mg_Ir/cm² (pristine), 0.21 mg_Ir/cm², 0.39 mg_Ir/cm², 0.60 mg_Ir/cm², 0.94 mg_Ir/cm²) are evaluated to investigate the effect of IrO₂/TiO₂ catalyst loading on the water electrolysis cell performance. The results indicate that cell Ohmic resistances of IrO₂/TiO₂ catalyst coated PTLs are lower than the one of pristine PTL. Moreover, the polarization studies show that cell performance increases with the increase of catalyst loading. In our study, the catalyst loading of 0.60 mg_Ir/cm² is expected as the optimum for PEM electrolyzer.