Operando soft x-ray spectroscopy characterization of interfacial charge transfer in energy materials and catalysis*

Soft x-ray spectroscopic techniques with operando capabilities offer the unique characterization in energy conversion/storage materials and catalysis in regards to the functionality, complexity, and interactions among constituents within. It has been found that the microstructure and composition of materials as well as the evolution process have a great influence on performances in a variety of fields, e.g., energy conversion and energy storage materials, chemical and catalytic processes. Operando soft x-ray characterization offers an opportunity to uncover the phase conversion, chemical environment change of elements and other very important information of solid/gas and solid/liquid interfaces in real time. We will overview a number of the experimental studies that successfully revealed the catalytic and electrochemical reactions in real time, e.g. solid (Au or hematite films)/liquid (water) electrochemical interface, Mg-ion batteries, and Li-S batteries. The experimental results demonstrate that the operando soft x-ray characterization provides the unique information for understanding the real reaction mechanism.