Low-Temperature Proton Exchange Membrane Of Sulfonated Polysulfone Enhanced By Phosphotungstic Acid Polydopamine-modified MOFs

Proton exchange membrane(PEM)is the key material of fuel cell in new energy.As an important part of fuel cell membrane electrode assembly,proton exchange membrane must have high proton conductivity,long service life,oxidation resistance,high membrane forming performance,easy to assemble into membrane electrode,low fuel and oxidant permeability.And fuel cells as a substitute for petroleum energy must also have low cost,easy to prepare and easy to store and other commercial properties.In this study,sulfonated polysulfone(SPSf)with low cost,easy access and good mechanical properties was used as the substrate to prepare proton exchange membrane with higher performance by introducing acid-base pair.In this work,the sulfonated polysulfone(SPSf)was doped with polydopamine(PDA),MOFs and phosphotungstic acid(HPW)to prepare a proton exchange membrane.Three methods were used to prepare the composite membrane.1.MOFs was doped into SPSf to prepare the composite membrane,then MOFs was used to catalyze the polymerization of dopamine in acidic dopamine solution.The amino group from PDA and the sulfonic acid group on SPSf form acid-base pairs.The acid-base pair can facilitate proton transfer.However,low conductivity of MOF results in a decrease electrical conductivity in the composite membrane.Moreover,the mechanical properties of composite membranes are poor,due to the limitations of experimental methods,so they cannot be used in fuel cells.2.Polydopamine is coated on the surface of MOF.This method not only improves the conductivity of MOF,but also indicates the doping amount.However,the composite membrane with high proton conductivity could not be obtained,because the sulfonation degree was too low.3.We introduced phosphotungstic acid(HPW)into the composite membrane.HPW and PDA interact to produce coordination.The composite membrane with the highest proton transfer rate obtained by this method is 20% PDA@MOF-75% HPWSPSf,which has a proton transmittance of 21 m S/ cm.The proton conductivity of the SPSf membrane used as a control experiment was 6 m S/ cm.The proton conductivities of SPSf of 20% PDA@MOF and SPSf of 75% HPW are 3 m S/ cm and 9 m S/ cm,respectively.In single cell performance test,20% PDA@MOF-75% HPW-SPSf has A power density of 70 m W/ cm2,which is 3.7 times that of 75% HPW-SPSf.