Study On Proton Conduction Performance Of Functionalized Crystalline Metal-organic Frameworks And Hybrid Membranes

Proton exchange membrane fuel cell(PEMFC)is a clean and efficient new energy source with unique advantages such as high power density,long service life and wide application fields.It is considered as a new generation of energy technology to alleviate energy crisis and environmental problems.However,the current commercial Nafion proton exchange membrane still has the disadvantages of poor water retention performance and high cost.It is necessary to develop proton exchange membrane materials with high proton conduction performance and excellent stability.Metalorganic frameworks(MOFs)have been widely used in various fields due to their chemical and structural diversity.The doping of MOFs in polymer matrix can not only increase the proton transfer path in the membrane,but also help us to understand the proton transfer path and mechanism in the hybrid membrane.In this paper,MOF is modified by means of post-synthesis modification and encapsulation of functional materials,so as to obtain high-performance proton conductor,and then the hybrid film is prepared by doping it in the polymer substrate,and its proton conduction performance is studied.The paper is specifically divided into two parts:(1)PVDF/PVP was used as a substrate to prepare a PEM.In order to further improve the proton conductivity of PEM,{[FeⅢ3L2(H2O)6]·3(OH)}n(FeⅢ-MOF)(H3L=1-aminobenzene-3,4,5-tricarboxylic acid)was doped into the PVDF/PVP substrate to prepare a hybrid membrane.Product FeⅢ-MOF is obtained by oxidizing｛[FeⅡ3L2(H2O)6]·3H2O｝n(FeⅡ-MOF),and FeⅢ-MOF exhibited much higher proton conductivity(66 times,at 98%RH and 70℃)than Fell-MOF,confirming that PSO has a promoting effect on proton conduction.The prepared hybrid membrane also shows high proton conduction performance.The proton conductivity of the hybrid membrane(1.77×10-3 S·cm-1)far exceeds those of FeⅢ-MOF and the original blend membrane.This work suggests that MOF-doped PVDF/PVP composites have considerable application potential in fuel cells.(2)The proton conductivity of MOF-808-4SA was improved by encapsulating choline chloride(ChCl).The results show that the introduction of ChCl can greatly promote the proton conductivity of MOF-808-4SA,and the proton conductivity of MOF-808-4SA increases by two orders of magnitude at 60%RH and 30℃.The composite ChCl@MOF-808-4SA can also maintain good proton conductivity at medium and low humidity(30%-60%RH),and the proton conductivity reaches 1.47×10-2 S·cm-1 at 60%RH and 80℃.Then we doped ChCl@MOF-808-4SA into Nafion substrate to prepare hybrid films.The hybrid membrane can show excellent proton conductivity at 60%RH,and its proton conductivity reaches 0.033 S·cm-1 at 80℃,which is 2.6 times that of Nafion,indicating that the hybrid membrane has considerable application potential in the field of fuel cells.