Tertiary sulfonium as a cationic functional group for hydroxide exchange membranes

Tertiary sulfonium is introduced as the cationic functional group for hydroxide exchange membranes (HEMs). The methoxyl-substituted triarylsulfonium functionalized HEM (i.e., PSf-MeOTASOH) exhibits excellent thermal stability (TOD: 242 °C), acceptable hydroxide conductivity (15.4 mS cm−1 at 20 °C), and good chemical stability. Our work shows that, similar to nitrogen and phosphorus, a sulfur element with designed side groups can also be used to construct HEM cationic functional groups.