磷酸化杂化膜高效质子传递通道的构筑机制及调控

发布时间：2018-04-13 06:27

本文选题：质子交换膜 + 磷酸化　；参考：《天津大学》2014年博士论文

【摘要】：化学、拓扑结构优化是高性能燃料电池用质子交换膜设计及制备的关键。相较于常用的酸性质子传递基团磺酸根，两性基团磷酸根具有适中的得失质子能力、较高的保水特性及较低的质子传递能垒，因而向膜内引入磷酸基团作为质子传递位点成为质子交换膜领域的新方向。但高分子磷酸化较为困难，直接向膜内掺入含磷酸根的小分子，在电池工作环境中易发生流失，因此膜材料磷酸化新方法的研究成为重要科学问题。基于上述背景，本研究提出将有机无机杂化膜构建与膜磷酸化相结合，使用无机材料负载磷酸基团，并引入有机高分子膜基质，制备出磷酸化杂化质子交换膜。通过对无机材料化学及拓扑结构调控，可优化介观尺度杂化相界面，提高膜内有效质子传递位点数、构建高效质子传递通道、强化质子传递基团间的协同作用，为磷酸化质子交换膜的理性设计提供参考。本研究开发出先环氧基活化、后三氯氧磷磷酸化的高效通用方法，具体工作如下：（1）将表面接枝磷酸化有机链段的SiO2引入磺化聚醚醚酮（SPEEK）中构建磷酸化杂化膜，考察SiO2表面的有机链段长短对颗粒磷酸化程度及杂化膜内有效质子传递位点数的影响。发现有机长链可突破短链的单层化学改性限制，但SiO2表面接枝的有机短链更有利于提高膜内有效质子传递位点数，质子传导率最高可达0.335S cm-1（60oC、100%RH）。（2）将磷酸化的介孔硅引入SPEEK构建磷酸化杂化膜，考察磷酸基团数量、磷酸改性位置，及介孔硅内部孔道结构对颗粒磷酸化程度、杂化膜内质子传递通道的影响。发现扩大介孔孔径可增大磷酸化改性程度，，一维贯通介孔孔道有利于在无机材料主体内部形成连续贯通的质子传递通道，提高杂化膜导质子性能。（3）将多级磷酸化的介孔中空SiO2引入壳聚糖构建杂化膜，考察化学、物理多重磷酸化方式对杂化膜质子传导协同促进作用。发现介孔中空SiO2表面负载磷酸基团，可与膜基质中羟基、氨基形成氢键网络体系；壳层的磷酸化介孔孔道可形成连续贯通质子传递通道；中空空腔起到“酸池”作用，高效负载含磷酸根小分子；多种方式共同提升杂化膜质子传导性能。（4）将磷酸基团同时作为质子供体受体的促进传递机理扩展，于介孔硅表面负载碱性基团氨基，引入Nafion后构建杂化膜。考察分别由无机材料及膜基质高分子负载的质子传递基团间协同作用对膜性能的影响。发现SiO2表面负载氨基可强化杂化相界面间质子传递基团协同作用，形成沿无机表面的高效质子传递通道，促进质子传递，杂化膜质子传导率最高可达0.339S cm-1（115oC，100%RH）。
[Abstract]:Optimization of chemical and topological structure is the key to the design and preparation of proton exchange membranes for high performance fuel cells.Compared with the acid proton transfer group sulfonic acid group, the amphoteric phosphate group has moderate proton gain and loss ability, higher water retention property and lower proton transfer barrier.Therefore, the introduction of phosphoric acid groups as proton transfer sites into the membrane has become a new direction in the field of proton exchange membrane.However, the phosphorylation of polymer is difficult, and it is easy to lose small molecules containing phosphate radical in the membrane. Therefore, the study of new method of phosphorylation of membrane materials has become an important scientific problem.Based on the above background, the phosphorylation hybrid proton exchange membrane was prepared by combining organic-inorganic hybrid membrane construction with membrane phosphorylation, using inorganic materials to support phosphate groups, and introducing organic polymer membrane matrix to prepare phosphorylated hybrid proton exchange membrane.By regulating the chemical and topological structure of inorganic materials, the mesoscopic scale hybrid phase interface can be optimized, the number of effective proton transfer sites in the membrane can be increased, the efficient proton transfer channels can be constructed, and the synergism among the proton transfer groups can be strengthened.It provides reference for rational design of phosphorylated proton exchange membrane.In this study, an efficient and general method for phosphorylation of phosphorylated phosphoric acid was developed. The main work is as follows: 1) introducing the SiO2 of surface phosphorylated organic chain into sulfonated polyether ether ketone (SPEEK) to construct phosphorylated hybrid membrane.The effects of the length of organic segments on the phosphorylation of particles and the effective proton transfer sites in hybrid membranes were investigated.It is found that long organic chains can break through the monolayer modification limits of short chains, but the organic short chains grafted on the surface of SiO2 are more conducive to increasing the effective proton transfer sites in the membranes.The highest proton conductivity can be up to 0.335s cm ~ (-1) ~ 60oC ~ (1) ~ (100) RH ~ (2)) phosphorylation hybrid membrane was constructed by introducing phosphorylated mesoporous silicon into SPEEK. The phosphorylation degree of particles was investigated by the number of phosphoric acid groups, the modified position of phosphoric acid, and the internal pore structure of mesoporous silicon.Effects of proton transfer channels in hybrid membranes.It is found that increasing mesoporous pore size can increase the degree of phosphorylation modification, and that one-dimensional penetrating mesoporous channel is conducive to the formation of continuously penetrating proton transfer channels in the main body of inorganic materials.To improve the proton conductivity of hybrid membrane, we introduced the mesoporous hollow SiO2 into chitosan to construct the hybrid membrane. The synergistic effect of chemical and physical multiple phosphorylation on proton conduction of hybrid membrane was investigated.It was found that the surface of mesoporous SiO2 was loaded with phosphoric acid groups, which formed a hydrogen bond network system with hydroxyl groups and amino groups in the membrane matrix, the phosphorylation of mesoporous channels in the shell layer formed a continuous penetrating proton transfer channel, and the hollow cavity acted as an "acid pool".In order to improve the proton conductivity of hybrid membrane, the phosphoric acid group was extended to the surface of mesoporous silicon as a proton donor receptor, and the basic group amino group was loaded on the surface of mesoporous silicon.The hybrid membrane was constructed after the introduction of Nafion.The effects of synergistic action of proton transfer groups supported by inorganic materials and membrane matrix on membrane properties were investigated.It is found that the SiO2 surface loaded with amino groups can enhance the synergism of proton transfer groups between the hybrid phase interfaces and form a high efficiency proton transfer channel along the inorganic surface to promote proton transfer. The highest proton conductivity of the hybrid membrane can be up to 0.339S cm-1 / 115oC ~ (1) C ~ (100) RH ~ (-1).
【学位授予单位】：天津大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TM911.4

【共引文献】