(La,Ae)FeO3表面原子结构的原位调控及其氧还原反应机理的研究

我国提出要在2060年实现碳中和。固体氧化物燃料电池(SOFC)具有碳排放低、稳定性好和运行成本低等优点，有着广阔的应用前景。钙钛矿氧化物是最常用的SOFC阴极材料，其表面缓慢的氧还原反应是SOFC效率的限制因素。理解钙钛矿表面原子结构对氧还原反应机理的影响，从而设计更高效的阴极材料，一直是SOFC基础研究的热点和难点。本项目以(La,Ae)FeO3为研究对象，在制备、表征和理论三个方面进行创新：对电解质基片进行高温退火和酸处理，得到原子平整表面，实现对钙钛矿表面原子结构的精确控制；将电化学测试和激光溅射制膜技术（PLD）结合，开发原位PLD技术，在薄膜生长过程中对表面反应速率进行表征，建立表面原子结构和氧还原速率的对应关系；将表面结构参数纳入缺陷化学和微观动力学模型，建立更全面的热力学和动力学工具。最终揭示钙钛矿阴极材料表面原子结构和氧还原反应机理的构效关系，指导SOFC阴极材料的开发。

China has set the goal to achieve carbon neutrality by 2060. Solid oxide fuel cell (SOFC) is a clean energy technology of great potential because of its advantages such as low carbon emission, long term stability and low operation cost. Perovskite oxide is the most widely used cathode material for SOFC. However, the slow reaction rate of the oxygen reduction reaction on its surface has limited the global efficiency of the cell. Understanding the correlation between the surface atomic structure and the oxygen reduction mechanism has been an important but difficult topic for the SOFC research. In this project, we use (La,Ae)FeO3 as the model system to develop new research strategies on sample fabrication, characterization and modeling: By annealing the electrolyte single crystal substrate at high temperature and etching in HF, we achieve atomically flat surface, which enable us for controlling the surface structure at atomic resolution; By combing the pulsed laser deposition and electrochemical measurement, we develop the in situ PLD technique, which can measure the reaction rate during the film deposition process. This enable us to build the directly connection between the surface structure and the reaction rate; By introducing the surface structure parameters into the defect chemistry and micro-kinetic model, we build a thermodynamic and kinetic model to give a the whole picture of oxygen reduction reaction mechanism. Finally, we are able to build the correlation between the surface atomic structure of the perovskite oxide and the oxygen reduction reaction mechanism. This correlation can guide the design of SOFC cathode materials.