Well-dispersed radical scavengers for highly durable hydrocarbon-based proton exchange membranes in water electrolysis

A highly durable hydrocarbon (HC)-based composite membrane is prepared by dispersing cerium oxide (CeO2) as a radical scavenger in a sulfonated poly(arylene ether sulfone) (SPAES) ionomer for application in proton exchange membrane water electrolysis (PEMWE). Ball milling and sonication processes are utilized and compared to disperse CeO2, and their effectiveness in influencing the membrane characteristics are evaluated. The inclusion of CeO2 enhances the chemical stability and mechanical properties of the composite membranes compared to those of the pristine membrane. However, because of the non-ionic conducting nature of CeO2, the proton conductivities of the composite membranes are lower. Nonetheless, the ball milling process mitigates the decline in proton conductivity to a greater extent than the sonication process. During PEMWE, the cell performance of the composite membrane with ball-milled CeO2 is superior to that with sonicated CeO2, showing a 1.2-fold improvement at 1.9 V. Additionally, after the durability test, the cell performance and molecular weight decrease by only 2 % and 3 %, respectively, for the membrane with ball-milled CeO2, in contrast to the 20 % and 30 % decreases exhibited respectively by the pristine membrane. Therefore, the HC-based composite membrane incorporating well-dispersed radical scavengers shows promise as a highly durable proton exchange membrane for water electrolysis applications.