反应诱导合金催化剂动态表面偏析的原位识别与机制研究

反应气氛诱导合金催化剂表面偏析的原位电子显微学表征，对于动态识别反应中催化剂的真实活性相、深入理解其微观催化本质，以及合金催化剂的理性设计都具有重要的科学价值。本项目拟从气氛诱导合金表面偏析机制研究出发，综合运用多尺度原位成像（NAP-STM、ESEM、ETEM）与原位表面分析技术（NAP-XPS、in situ FTIR），系统研究合金原子偏析对单一/多组分气氛的响应与竞争机制。进一步，在反应环境中，运用原位电子显微学方法，识别合金催化剂的表面偏析过程，揭示反应中真实活性相及其局域微结构，建立动态构-效关系。并依托模型催化体系，从原子分子尺度动态理解微观催化机制。结合从纳米颗粒到表面模型催化剂的多尺度原位表征，建立基于动态偏析模型的新机制，实现对现有合金催化理论的动态化修正。

In situ observation of dynamic surface segregation in bimetallic catalysts during reaction is of significant merit in identifying the real active structure in a working catalyst, understanding the fundamental reaction mechanism and pursuing the rational design of new catalyst materials. Herein, we propose a systematic study on the reaction driven segregation on alloy catalysts by utilizing multi-scale in situ microscopies including NAP-STM, ESEM and ETEM, along with various in situ surface characterizations such as NAP-XPS and in situ FTIR, in order to reveal the underlying mechanism and dynamic behaviors of adsorption/oxidation induced segregation. Furthermore, employing ETEM and NAP-STM, we will directly visualize the dynamic segregation of bimetallic catalyst under reaction condition and resolve the atomic structure of the real active sites during reaction, as to establish the structure-reactivity relationship based on dynamic structural evolution. Accordingly, a model catalyst study on alloy surfaces will be carried out to elucidate the reaction mechanism at an atomic/molecular level. By combining the multi-scale study of both binary nanoparticles and model catalysts, we are proposing a dynamic segregation effect in bimetallic catalyst as a supplement to the current theories of alloy catalysis from the dynamic point of view.