表面修饰碳纳米管对负载金属纳米粒子作用机制的原位电子显微研究

Carbon nanotubes (CNTs) have been used as a support material of metal nanoparticles (NPs) in many fields, such as chemical catalysis, hydrogen storage, and direct alcohol fuel cells, and so on. The significant differences of surface tensions between CNTs and metal NPs go against the adhesion of NPs on CNTs surface. However, they can be bonded heterogeneously through surface defects, doping elements and functional groups by modifying CNTs surface. Nowadays, the key issue is how to interpret the interactions of doped or functional CNTs to supported metal NPs. In this project, the metal NPs (Pd, Ni) supported on CNTs will be investigated by in-situ high-resolution transmission electron microscopy, electron energy loss spectrometer, x-ray photoelectron spectroscopy etc. The functional groups and doped elements on the surface of CNTs will be quantified, and the fine structures of the interface between NPs and CNTs will be evaluated. The results will reveal the interaction between metal NPs and CNTs, establish the related theories, and suggest a new preparation pathway of metal NPs supported on CNTs with controllable morphology and size, which will not only develop the preparation methods and research progress of nano-composite, but also provide a new theoretic basis and experimental evidence for solving the problems of interfacial and heterogeneous bonding between metal NPs and CNTs.

碳纳米管作为金属纳米粒子的载体材料，在催化、储能、燃料电池等领域广泛应用。但碳纳米管与金属纳米粒子之间表面张力的差异显著，不利于金属纳米粒子附着。通过对碳纳米管表面修饰，利用表面缺陷、官能团及掺杂物种可实现较好的异质连接。目前存在的关键问题是如何解析掺杂及官能化碳纳米管对负载金属纳米粒子的作用机制。本项目选取金属纳米粒子(Pd,Ni)/碳纳米管为研究对象，采用原位高分辨电镜、电子能量损失谱、X射线光电子谱等表征方法，定量分析官能团种类、掺杂物种分布，评价金属纳米粒子/碳纳米管界面处精细结构，揭示表面修饰碳纳米管对金属纳米粒子的作用机制，建立相关理论，以指导开发形貌、尺寸可控的金属纳米粒子/碳纳米管复合功能材料，推动金属纳米粒子/碳纳米管复合材料的研究进展，为解决金属纳米粒子/碳纳米管复合材料界面结合问题及提高异质连接提供新的理论基础和实践依据。

纳米碳负载金属纳米粒子材料在催化、储能、燃料电池等领域扮演着重要角色。如何使负载金属纳米粒子的尺寸均一、分散均匀以及活性位点多等是重要研究内容，众多影响因素中载体与负载金属纳米粒子之间的相互作用对调控这些结构特征起重要作用。本项目以纳米碳材料中具有代表性的碳纳米管为主要载体，钯、钌等为负载金属制备碳载金属催化剂。由于碳纳米管表面疏水且显惰性，不利于锚定金属纳米粒子，需要对碳纳米管表面修饰，利用表面缺陷、官能团及掺杂物种提供锚定位，实现金属与载体之间的异质连接。为此，对碳纳米管表面改性并定性、定量分析改性碳纳米管结构特征，以及解析表面改性碳纳米管与负载金属纳米粒子之间作用机制需要细致研究。本项目主要利用先进电子显微学表征手段研究纳米碳（碳纳米管等）负载金属纳米粒子（钯和钌等）催化剂表界面微结构特征，如：采用高分辨、电子能量损失谱、X射线能谱等分析表界面结构、官能团种类、掺杂物种分布等，并通过原位加热样品台原位研究不同表面改性碳纳米管负载金属催化剂的热稳定性，从而揭示改性碳纳米管表面与负载金属纳米粒子的相互作用。该项研究为指导开发形貌、尺寸可控的金属纳米粒子/纳米碳复合功能材料，推动金属纳米粒子/纳米碳复合材料的研究进展，解决金属纳米粒子/纳米碳复合材料界面结合问题及提高异质连接提供新的理论基础和实验依据。. 目前，相关研究成果已经整理总结，发表在国际学术期刊上20余篇，参加学术会议10余次。