固体氧化物电解池双钙钛矿氢电极材料的制备、催化反应机理及性能衰减机理研究

High-temperature steam electrolysis with solid oxide electrolysis cell (SOEC) is a clean and highly efficient approach for hydrogen production. One of the main problems with SOEC is relatively fast degradation of the hydrogen electrode material at high-temperature and high-humidity environment. We propose to use novel double perovskite-type materials to resolve the problem. This project will carry out systematic studies on such materials to achieve high-performance SOEC by tailoring materials compostion and structure: first design and selection of materials system by theoretical calculation, then optimisation of the materials preparation processes. The double perovskite-type powders will be prepared via sol-gel, and the green bodies of the hydrogen and oxygen electrodes and electrolyte of SOEC will be prepared via tape casting and lamination, and unit electrolysis cell by co-sintering. The chemical stability, electric conductivity under polarization at high temperature and high humidity of the novel materials as the hydrogen electrode of SOEC will be thoroughly studied, and correlated with their composition and structure. The mechanism of the catalytic reaction and the degradation of the double perovskite-type electrode material for SOEC will be clarified. It is expectable that high-performance and high stability SOEC can be obtained by using the novel double perovskite-type materials, which will provide a choice for electrode materials and improve SOEC performance and lay a foundation for the application of large-scale hydrogen production via high-temperature steam electrolysis using the heat from nuclear energy.

高温电解水蒸汽是一种高效清洁的制氢新方法，其核心是固体氧化物电解池(SOEC)，制约其性能的关键问题是SOEC氢电极在高温高湿电解模式下材料的老化而导致性能明显衰减。具有优异耐高温和高湿特性的新型双钙钛矿材料有望成为解决这一问题的有效途径。本项目拟围绕高性能SOEC研发，系统地探究一种双钙钛矿新型电极材料制备方法、结构调控及其高温高湿和外加电场作用下的结构和性能变化规律。以理论计算辅助设计材料组分，采用溶胶凝胶法合成双钙钛矿粉体；经流延和层压法成型并经共烧结一次性制备得到高质量低极化电阻的单体电解池；将深入研究双钙钛矿材料用作氢电极的化学稳定性，揭示电极材料的电导、电极化规律与材料结构间的相互关系，最终建立双钙钛矿电极材料组成-结构-性能的内在关联，并阐明其制氢催化反应和性能衰减机理，有望获得高性能高稳定的SOEC，为利用核能高温工艺热电解水蒸汽大规模制氢奠定扎实的理论和实际应用基础。

高温固体氧化物电解池氢电极材料是材料领域的研究热点。传统的Ni-YSZ复合氢电极材料存在着如Ni烧结团聚、Ni高温挥发、易杂质中毒等尚未解决的难题。本项目重点考察研究了双钙钛矿材料作为电解池电极材料的可行性。结果表明，双钙钛矿材料是一种非常有希望能替代Ni-YSZ的SOEC氢电极材料。首先对选择的双钙钛矿氢电极材料进行了理论设计，并预测了相关性能。用不同的方法合成出双钙钛矿氢电极材料粉体，测试了双钙钛矿材料本身的物化性能及与电解质材料的相容性。经性能测试分析，初步筛选出性能较好的双钙钛矿材料（Sr2FeNbO6，SFN）进一步制备出了相应的半电解池、电解池，并对材料在电解过程中的综合性能表现进行了评估。建立实验对照，深入研究了SFN的电化学性能；从动力学角度深入探讨了SFN作为SOEC氢电极催化分解H2O(g)的机理。结果表明：相同实验条件下，SFN-YSZ的电化学性能和制氢性能表现均优于Ni-YSZ。在国内外知名期刊上发表SCI论文5篇，参加国内会议10人次，申请国家发明专利6项，目前已授权4项，完成了项目各项指标。