Atomic Resolution Electron Microscopy Characterization of Energy Functional Materials

Functional energy materials play important roles in energy conversion and storage technologies, including renewable electricity, fuel cells battery and electricity driven water splitting. The performance of functional energy materials depends on the nanoscale surfaces, defects and interfaces that present in the nanostructures. In this thesis, I will demonstrate the atomic-scale structures and properties of two representative types of energy related materials, including polycrystalline cadmium telluride semiconductor and transition metal oxides catalyst. The co-segregation of Se and Cl was revealed by STEM/EDS/EELS. The co-passivation of defects states in band gap was found based on STEM images of atomic grain boundary structure. The atomic scale electric field distribution in cadmium telluride solar cell device using 4-dimensional transmission electron microscopy was revealed. The structural and chemical characterization of CoxMn3-xO4 nanoparticles in oxygen evolution reaction was studied by STEM/EELS. The electrochemical performance of the nanoparticles can be correlated to the elemental distribution and atomic arrangement and vacancies at the nanoparticle surfaces. The research results reveal the importance of the atomic arrangement and elemental distribution in energy materials to the physical properties of the materials. A fundamental understanding of the structure-property relationship in these energy materials greatly advances our ability to design and develop novel functional devices at nanoscale.