Study on the effect of IrO2/TiO2 catalyst composition coated on porous transport layer on the performance and durability of polymer electrolyte membrane water electrolysis

Abstract

The porous transport layer (PTL) is an essential component of the polymer electrolyte membrane water electrolysis (PEMWE). With the multi-function of electrical and mass transport, PTL must deal with surface passivation during long-term operation, acidic environment, and high operating temperature. A thin IrO₂/TiO₂ catalyst layer is coated on the PTL surface by combining the spray-coating and thermal treatment methods. This catalyst layer not only prevents the PTL passivation but also enhances the performance of PEMWE. In this study, by controlling the ratio of Ir and Ti precursors in the catalyst ink, 4 samples with different Ir:Ti ratios (PTL3.1, PTL4.1, PTL6.1, PTL9.1) are evaluated to assess the effect of varying Ir:Ti ratios on the water electrolysis performance. The results indicate that the PEMWE performance of IrO₂/TiO₂ catalyst coated PTLs increases with the Ir:Ti ratio. In our study, the Ir:Ti ratio of 6:1 is expected as the optimum for the PEMWE. The durability test results also show that the IrO₂/TiO₂ catalyst coated PTL helps to limit the degradation of PTL after the accelerated stress test.