ZnO暴露晶面和缺陷的调控及其催化高氯酸铵热分解机理研究

To overcome the low dispersity and poor catalytic activity of the nanocatalyst/oxidant composites, this project will be proposed to study the influence of ZnO exposed facets on the catalytical thermal decomposition characteristics and kinetics of ammonium perchlorate (AP), and establish a structure-property relationship between ZnO exposed facets and catalytical thermal decomposition characteristic parameters of AP by means of DSC and PDSC technology. In addition, the component of thermal decomposition products of AP/ZnO composites will be investigated by using TG-IR and DSC-MS combined test system. Moreover, the first-principles calculation will be employed to calculate the adsorbed state, transition state, final state and reaction barrier of NH3 and HClO4 on the surface of ZnO nanocrystals. As a result, the catalytical thermal decomposition mechanism of AP dependent on the ZnO exposed facets will be revealed, the special ZnO exposed facet which can make the largest contribution to the catalytical thermal decomposition of AP will be also found, and thus providing guidance for designing the exposed facet structure of ZnO. Based on these results, ZnO nanocrystals with different exposed facets will be prepared controllably on the surface of AP microspheres by a wet chemical synthesis. The obtained ZnO/AP core-shell nanocomposites will exhibit good dispersity and excellent self-catalytical properties, and thus lay a technical foundation for their application in the high-performance solid propellant.

为解决纳米催化剂/AP复合材料催化活性低及催化机制缺乏理论和实验证据的问题，本项目拟通过第一性原理，从分子和原子水平计算AP的第一中间分解产物NH3和HClO4在ZnO各暴露晶面及缺陷上的吸附态、过渡态、终态及反应势垒，揭示ZnO暴露晶面及缺陷催化AP热分解的机制，找出ZnO表面结构中催化AP分解贡献最大的暴露晶面及缺陷，同时结合水浴法和气氛热处理法制备出暴露晶面、缺陷及所占比例不同的ZnO纳米晶，并采用DSC和PDSC等技术手段，研究ZnO暴露晶面、缺陷对AP催化热分解特性及反应动力学的影响，建立ZnO暴露晶面、缺陷与催化AP热分解特征参数之间的构效关系；利用TG－IR、DSC－MS联用等手段，研究AP/ZnO体系热分解产物组成；从理论和实验两个方面揭示ZnO纳米晶催化AP热分解的机理，从而为制备出催化性能优异的ZnO纳米晶提供理论指导。

本项目按原计划主要研究ZnO纳米晶催化AP热分解的机理，从而为制备出催化性能优异的ZnO纳米晶提供理论指导，在获得国家自然科学基金资助后，该项目进展顺利。. 首先，通过过第一性原理，从分子和原子水平计算AP的第一中间分解产物NH3和HClO4在ZnO各个外露晶面及缺陷上的吸附态、过渡态、终态及反应势垒，揭示ZnO外露晶面及缺陷催化AP热分解的机制。继而，在实验上合成ZnO纳米片，并调控其外露晶面及所占比例，分析ZnO纳米片暴露晶面对AP催化分解特性和机制。在这个工作的基础上，ZnO纳米片堆叠所造成的其比表面积较小的问题被关注到。通过ZnO纳米片组装的分级结构，ZnO微球可以很好地解决这个问题，使ZnO对AP热分解的催化性能有了显著的提高。之后，继续深入探索了缺陷调控对ZnO催化AP热分解性能的影响，在ZnO分级微球的基础上，通过调控变价过渡金属种类及浓度，调控ZnO微球中缺陷的含量，从而实现对ZnO催化AP热分解性能的调控。至此，从理论和实验两个方面揭示了ZnO纳米晶催化AP热分解的机理及调控手段。此后，我们关注到了新的功能材料金属骨架材料具有更大的比表面积，将其应用到制备催化性能优异的ZnO复合材料当中，最终，ZnO微球与ZIF-67纳米多面体复合后，性能得以提升。