高稳定自支撑式的高温质子交换膜燃料电池催化层的构筑及性能研究

Considering the issues about the electrocatalyst support corrosion and the phosphoric acid loss under the practical rigorous condition of high temperature proton exchange membrane fuel cells (HT-PEMFCs), this project will construct one kind of composite nanofibers structured self-support catalyst layer with high stability and less acid loss characteristics, by adopting the combination of the metal oxide with low d electrons, good stability and synergistic catalytic effect and the electron/proton conducting polymer with acid hold ability as the catalyst support, and by using electrospinning, chemical polymerization and in-situ Pt reduction methods. The effects of metal (in TiO2, CeO2, etc.) on the Pt electronic structure and ORR activity will be investigated, and the influence rules of the obtained catalyst layer on the transportation and migration behavior of proton, electron, reactants and reaction productions will be clarified by electrochemical technology, modern spectroscopy, and density functional theory calculations. In addition, single cell performance and stability of the membrane electrode assembly (MEA) under high temperature condition (150-180 oC) will be observed to validate the applicability of the obtained catalyst layer. Based on this project, an alternative means and a novel structure will be developed to prepare MEA with high performance and high stability for HT-PEMFCs.

针对高温质子交换膜燃料电池（HT-PEMFCs）实际工况条件苛刻，膜电极中催化剂载体易氧化腐蚀及磷酸流失等问题，本项目采用耐腐蚀且具有协同催化效应的低d电子金属氧化物与具有电子/质子传导能力且可抑制酸流失的有机导电聚合物的复合体系作为支撑体，通过静电纺丝、化学聚合和原位还原等，构筑一种耐腐蚀且可抑制磷酸流失的复合纳米纤维结构的自支撑式催化层。采用电化学方法、现代谱学显微技术，结合理论计算等，探讨Ti，Ce等金属氧化物对Pt电子结构及氧还原反应（ORR）催化活性的影响，阐明复合纳米纤维催化层体系对膜电极中电子、质子、反应物、产物的传输迁移速率的影响及其规律；并通过在实际高温工况条件（150-180 oC）下测试单体电池的性能和稳定性，评估所制备催化层体系的实用性。本项目将为制备高性能和高稳定性膜电极提供一种新思路和新方法。

高温质子交换膜燃料电池的特有优势使其具有诱人的发展前景，但高温强酸的操作环境使其在关键材料、部件、结构及组装等方面需要更高的要求。面对优势和挑战，许多国家和地区的研究机构已经在此领域展开广泛研究。本项目采用金属氧化物与有机导电聚合物的复合体系作为支撑体，通过静电纺丝、化学聚合和原位还原等，构筑复合纳米纤维结构的自支撑式催化层。通过调变纺丝溶液的浓度、纺丝条件、化学聚合条件等，优化复合纳米纤维的尺寸。并借助静电纺丝法构筑共同传导质子/电子的催化层，纺丝过程中，调节Pt盐的浓度不仅影响所得催化层的Pt含量，也将影响纺丝所得纤维的形貌，进而影响电催化剂的ORR活性及电池性能。进而探索静电纺丝法所制备的复合纳米纤维在高温质子交换膜燃料电池中的应用。基于导电聚合物的特点，项目进一步研究导电聚合物在膜电极制备和燃料电池中的应用，结果表明，有序导电聚合物纳米阵列多孔电极不仅有利于电极表面物质的传输迁移，降低燃料电池的传质极化损失，而且可大幅提高电催化剂的利用率。