Addition of modified hollow mesoporous organosilica in anhydrous SPEEK/IL composite membrane enhances its proton conductivity

Sulfonated hollow mesoporous organosilica (sHMO) was successfully prepared. SP/IL/sHMO-x (x = 2.5, 5.0, 7.5 and 10 wt%) composite membrane was synthesized by dispersing ionic liquid (IL) in sHMO, with sulfonated polyether ether ketone (SPEEK, SP) as the matrix. For comparison, unsulfonated HMO and SP/IL/HMO-x membranes were also prepared. The membranes were characterized by Fourier transform infrared spectroscopy (FT-IR), thermogravimetric (TG) analysis, dipping and AC impedance. FT-IR results showed no new chemical bond was formed among SPEEK, IL and organosilica, and the components were bound by intermolecular hydrogen bonding. The results of TG showed that the membranes were stable up to 240 °C. The IL loss study showed that the retention of IL increased with the increase of the content of organosilica, while sHMO composite membrane showed lower IL retention capacity than HMO composite membrane. Proton conductivity study showed that sHMO also contributed to the conductivity of the membrane. The conductivity of the SP/IL-30/sHMO-7.5membrane was 1.13 mS cm−1 at 200 °C, which is twice that of the SP/IL-30/HMO-7.5 (0.60 mS cm−1). At 200 °C, the conductivity of SPEEK/IL-50/sHMO-7.5 reached 10.5 mS cm−1. The anhydrous composite membrane could be used in PEMFCs under medium temperature condition.