锰基钙钛矿的脱溶调控及应用于锂空电池阴极催化剂的研究

Exsolution is the chemical process of metal cations migrating from their crystallographic site to the surface of material and forming a socketed new phase as nanoparticles, which is regarded as a disruptive effect on the structure.What's more, the new interface between exsolved nanoparticles and parent oxides will also bring opportunities for new generation catalysts, recently. Based on our previous works on the synthesis and properties of perovskite structure oxides and electrochemical catalysis theory of transition metal d orbitals, we will focus on the exsolution reaction in perovskite structure manganite via different dimensions such as creating A-site ionic discrepancy, tailoring high-indexed facets and fabricating oriented films in this project. Different methods such as varying the strength of external electric field, changing oxidation or reduction atmosphere at high temperature, etc, will be employed in the exsolution process. Products of exsolution reaction will be used as cathode catalyst for Li-air batteries. The double functional catalytic activity will be particularly focused in promoting the catalysts preparation based on exsolution. In addition, we also will conclude the relationship between material structure and exsolution, and then build a exsolution-based strategy for optimizing the properties of materials. The project will facilitate the controllable tailoring of functional site in solid state materials by exsolution, which will provide theory foundation and technique for high-efficiency smart catalyst in new energy applications, and also helpful for the development of solid state chemistry.

脱溶是固体内部离子脱出晶格并在表面形成新相的化学反应，会影响材料结构的稳定性，而近期发现脱溶可以形成镶嵌在母体表面的纳米颗粒，这种新颖的界面结构必将为发展新一代催化剂提供机遇。基于我们课题组前期对钙钛矿氧化物合成与性能调控的研究，结合过渡金属d轨道的电催化理论，本项目选择锰基钙钛矿氧化物为研究体系，以A-位离子差异、高指数晶面及取向薄膜为切入点，分别采取外电场诱导、高温氧化或还原气氛等实验手段，开展面向锂空电池阴极催化剂表界面的系列脱溶反应研究，旨在提升其双功能催化活性，系统总结材料结构与脱溶调控的基本规律，阐明以性能为导向来优化材料定向脱溶的制备策略。本项研究将实现对固体材料功能位点进行脱溶调控，为制备高效智能型能源催化剂提供理论基础与实验手段，促进固体化学的发展。

钙钛矿脱溶可控制具有特定功能的结构单元从母体骨架中原位生长，形成新的复合相，脱溶出的纳米粒子与母体间具有强锚定作用，赋予材料良好的稳定性。本项目以锰基和铁基钙钛矿氧化物为研究体系，以A/B位离子差异、晶面等为切入点，分别采取高温氧化或还原,溶剂诱导等实验手段，开展面向锂空电池阴极催化剂表界面的系列脱溶反应研究，通过调节脱溶粒子与母体钙钛矿两相的协同作用，实现单一组分材料所无法达到的优越性能，系统总结材料结构与脱溶调控的基本规律，阐述锂空气电池性能与材料表界面结构之间的构效关系。利用同步辐射光源、散裂中子源等大科学装置以及原子尺度理论模拟深入探讨钙钛矿氧化物脱溶前后晶体结构和电子态的变化以及结构对催化性能的影响机制，系统总结脱溶制备的复合材料结构对锂空气电池性能起到的协助与促进作用，进而阐明以性能为导向来优化材料复合的制备策略。本项研究实现了对固体材料功能位点的脱溶调控，为制备高效能源催化剂提供理论基础与实验手段，对固体化学与能源转换领域具有重大意义。