(Invited) Probing the Atomic and Electronic Structure of Working Energy Materials with x-Ray Spectroscopy

Abstract

Improving energy conversion/generation/storage efficiency of energy materials has always been a great challenge. Monitoring the atomic/electronic structures close to interface in many important energy materials, such as nanostructured catalysts, artificially photosynthesizing materials, smart materials, and energy storage devices, is of great importance. Designing such a material with improved performance without understanding its atomic/electronic structures, and their changes under operating conditions, is difficult. Understanding and controlling the interfacial electronic structures of energy materials require in-situ characterizations, of which synchrotron x-ray spectroscopy is the one with many unique features. The last decade has witnessed a golden age of in situ synchrotron x-ray spectroscopy for energy materials. X-ray absorption spectroscopy can be used to determine unoccupied electronic structures while X-ray emission spectroscopy can be utilized to examine occupied electronic structure. The additional use of resonant inelastic X-ray scattering further reveals inter-band d-d excitation or intra-band charge transfer excitation that can reflect the fundamental chemical and physical properties. An emerging technique, scanning transmission x-ray microscopy is a spectro-microscopic approach, providing regional x-ray absorption spectroscopy, is also gearing up for energy science. This presentation will report recent studies and perspectives of the application of in situ/operando synchrotron x-ray spectroscopy to energy materials. Tamkang University (TKU) end-stations constructed at the Taiwan Photon Source (TPS) 45A & 27A beamlines for the x-ray spectroscopic investigation of energy materials will also be introduced.