Research On Low-dimensional Carbon Materials And UiO-66/chitosan Proton Exchange Membrane

Chitosan?CS?proton exchange membrane?PEM?has low cost,environmental friendliness and good methanol-blocking properties,however the low proton conductivity of pure CS membrane limits its application in direct methanol fuel cell?DMFC?.In this paper,low dimensional carbon nanomaterials and metal-organic framework materials were modified and the novel PEM materials were introduced into CS matrix to expand proton transport channels and improve proton conduction performance of the membrane.In this article,anatase titania anchored graphene oxide?TGO?,a three-dimensional material,was prepared by one-step hydrothermal method,and the TGO/CS composite membranes were prepared by solution casting method.The influence of TGO contents on membrane properties were analyzed by water uptake,oxidation stability,proton conductivity,and methanol permeability.When the TGO addition was 3 wt%and the temperature was 70?,the proton conductivity of the composite membrane reached21.36 m S cm^-1,which was higher than that of the pure CS membrane of 0.13 m S cm^-1.By analyzing the relationship between microstructure and properties of the composite membrane,the study results show that the doping of TGO effectively extends proton transport channels in the membrane and improves the proton conductivity and methanol barrier properties of the composite membranes.To further enhance the proton transfer performance of the TGO/CS membrane,sodium lignosulfonate?SLS?was introduced into the membrane.Scanning electron microscope?SEM?analysis showed that SLS can be uniformly distributed in the membrane,and proton conductivity tests at different temperatures on the membrane showed that the proton conductivity of CS/TGO/SLS composite membrane was improved.Theoretical analysis shows that the sulfonate group on SLS increases proton carrier sites of the composite membranes,constructs a continuous proton transport channels,and further improves the proton conductivity of the composite membranes.The above research shows that the doping of three-dimensional materials in the membrane can construct more efficient proton transport channels.In this study,one-dimensional SLS modified carbon nanotubes?SCNT?,two-dimensional graphene oxide?GO?and three-dimensional zirconium-based metal-organic frameworks?Ui O-66?were further synthesized into Ui O-66-SCNT and Ui O-66-SCNT@GO by self-assembly and used as filler materials for CS proton exchange membrane.The experimental results showed that all hybrid membranes exhibited enhanced proton conductivity,oxidation and mechanical stability with low swelling and methanol permeability.The CS/U-S@GO composite membrane prepared with 7 wt%Ui O-66-SCNT@GO doping has the best performance,with proton conductivity of 64 m S cm^-1 at 70?and methanol permeability of 1.86×10^-7cm² s^-1 at room temperature.The results show that SCNT and GO self-assembled Ui O-66 doped CS polymer provides a theoretical basis and data support for the practical application of PEM for DMFC.