钙钛矿/氧化铈复合电催化剂的仿生构筑与双功能氧催化机理研究

The composite catalysts of the perovskite/ceria show the excellent catalytic activity for the bifunctional oxygen catalysis reaction. Whereas, the catalytic mechanisms and microstructures of perovskite/ceria electrocatalysts are still needed to be intensively studied and optimized. Based on the previous work, the applicant indicates that the outstanding catalytic activity of perovskite/ceria composite catalyst can be attributed to three major factors: (1) the strong oxygen adsorption behaviors of CeO2; (2) a number of defect sites in the perovskite/ceria boundaries; (3) the strong interaction between perovskite and ceria. Based on this speculation, the two key scientific problems of this project which should be solved previously include the following items: (1) effects of the CeO2 microstructures on the oxygen adsorption behaviors of perovskite/ceria; (2) correlations between the oxygen catalytic activities and phase boundary properties of the perovskite/ceria composite catalysts. Based on this work, the perovskite/ceria composite catalysts with the high activity and biomimetic structures are fabricated by simulating the microstructures and respiratory functions of fish gills. Specifically, the CeO2 nanoparticles and perovskite nanotubes can act as the gill lamellas to capture oxygen and gill filaments to transfer oxygen species quickly, respectively. Furthermore, the “exsolution composite” method is applied to strengthen the phase boundary between perovskite and ceria and create oxygen vacancies in the phase boundary. Then, the effective perovskite/ceria composite catalyst can be constructed, and the third key scientific problem of this project, i.e. the exsolution behaviors and mechanisms of the perovskite/ceria composites can be explained. Using the above perovskite/ceria composite catalysts with the biomimetic structures and the organogel electrolyte prepared by acrylamide method, the all-solid-state flexible zinc-air batteries with high performance can be trial-produced.

钙钛矿/氧化铈复合催化剂显示了较高的双功能氧催化活性，然而其氧催化机理还需深入研究，结构尚需进一步优化。本项目提出钙钛矿/氧化铈具有较高活性的三要素为：1、氧化铈的强聚氧行为；2、两相界面处的大量缺陷位点；3、两相之间的强相互作用。基于此，本项目拟解决的前两个关键科学问题为：1、氧化铈结构特性对复合催化剂氧吸附行为的影响规律；2、界面属性对复合催化剂氧催化活性的影响机制。在此基础上，本项目通过借鉴鱼鳃的微观形貌与呼吸功能进行仿生设计，以氧化铈模仿鳃小片捕获氧，以钙钛矿纳米管模仿鳃丝快速传递氧，采用“脱溶复合”进一步提高两相的结合强度，并增加两相界面处的氧空位数量，进而构筑高效的钙钛矿/氧化铈复合催化剂，阐明本项目拟解决的第三个关键科学问题，即钙钛矿/氧化铈的“脱溶复合”行为和机制。最后，应用上述仿生催化剂和丙烯酰胺法制备的有机凝胶电解质，试制高性能全固态柔性锌空气电池。

针对钙钛矿氧催化剂比表面积小、氧吸附能力弱、活性位点少等本征属性，本项目将其与氧吸附能力强的氧化铈复合，制备了钙钛矿@氧化铈复合氧催化剂。系统研究了复合催化剂中各组分含量、结构特征、微观形貌、表面氧吸附类型、氧空位属性、复合方法等关键因素对此其氧催化性能的影响规律；揭示了钙钛矿@氧化铈的氧催化活性与CeO2的强氧吸附能力的关联；阐明了两相相互作用以及界面结合强度对钴基钙钛矿@氧化铈氧催化性能的影响机制；探明了BSCF/CeO2的两相界面存在压应力，压应力有效的防止了Sr元素的扩散，因而大幅度提升了BSCF的双功能氧催化活性与稳定性；归纳总结了钴基钙钛矿@氧化铈的氧催化机理与关键影响因素。为进一步提高钙钛矿与氧化铈两相的界面结合强度与相互作用，项目采用脱溶复合方法构筑了具有仿鱼鳃结构的钙钛矿@氧化铈复合氧催化剂；指出了静电纺丝工艺参数对钴基钙钛矿纳米纤维（管）的微结构与氧催化性能的影响行为；指出了CeO2在钙钛矿体相的析出、生长行为与机理，以及脱溶复合工艺对钙钛矿/氧化铈氧催化活性的影响规律。基于聚丙烯酰胺（PAM）水凝胶，通过组分、制备工艺与添加剂的优化改进PAM凝胶的机械强度、电导率和高低温耐受性能，开发出高性能固态电解质；发现在PAM凝胶中添加纤维素、聚乙烯醇和二甲基亚砜能大幅度提高PAM固态电解质的电导率、机械强度与耐高低温性能；基于具有仿生特征的氧催化剂与优化后的PAM凝胶电解质，试制了固态柔性锌空气电池，展示了较高的功率密度、放电容量与循环稳定性，拓宽了锌空气电池的应用场景。