X-ray Spectroscopy Studies of Energy Related Materials

Utilizing laboratory-based and synchrotron ambient-pressure X-ray spectroscopies, we have studied the non-destructive depth profiles of surface states and electronic structures as a function of temperature for materials related to energy and catalysis sciences. Polarized X-ray absorption spectroscopy and transmission electron microscopy were employed to provide information of the valence electron configurations and ligand crystal fields, helping to determine the material phases and chemical properties. In particular, we report our studies on TiO2 nanoparticles with and without the photodeposition of noble metals (Pt and Au) for photocatalysis, pyrite (cubic FeS2) for thin film solar cells, Bi2Ir2O 7 and Co monolayer for water oxidation, MnO2 nanowires for electrical energy storage applications, PbSe quantum dots for field-effect transistors, and Pd nanowires coated with Pt for hydrogen gas sensors. Our results have provided a more comprehensive understanding of these materials under in situ heating and various reacting gas exposures.