Anchoring HPW by amino-modified MIL-101(Cr) to improve the properties of SPEEK in proton exchange membranes

Incorporating phosphotungstic acid (HPW) in proton exchange membranes (PEMs) is an effective way to improve proton conductivity, but its leakage remains a problem. It can be solved by immobilizing acid in membranes to enhance the stability of PEMs. Herein, we proposed a novel sulfonated poly(ether ether ketone) (SPEEK) composite membrane (SPEEK/HPW@MIL) that was prepared by blending amino-modified MIL-101(Cr) to anchor HPW. In this work, HPW was anchored through hydrogen bond to minimize its leakage and enhance the overall compatibility. The incorporation of MIL-101(Cr)-NH 2 also helped lower the swelling ratio and improve the dimensional stability. Compared with pristine SPEEK and SPEEK/MIL membrane, the proton conductivity of the SPEEK/HPW@MIL composite membrane increased by 26% and 14%, respectively. The superior performance recommended a promising conception for anchoring HPW in PEMs.