A review of energy materials studied by in situ/operando synchrotron x-ray spectro-microscopy

Abstract

The high demand for scarce, clean and sustainable energy poses a challenge for modern societies. Increasing pollution leads to global warming, which can be stopped using current energy technologies and advanced energy materials. Synchrotron technology-based spectroscopy, such as x-ray absorption spectroscopy (XAS) is a useful tool for revealing the atomic and electronic structures of a material. It is becoming widely used for the advanced analysis of various energy materials, such as energy storage, energy conversion, energy generation, and energy saving materials. Scanning transmission x-ray microscopy (STXM) resembles scanning/transmission electron microscopy but performs a chemical microscopy function using x-ray photons, rather than an electron beam. Thus, the uniqueness of STXM is that it features the advantages of both XAS and microscopy, which are elementally sensitivity and spatially selectivity, in nanoscale chemical imaging. Furthermore, in situ STXM is an emerging tool for identifying spatially resolved electronic structural dynamics in various energy materials in their operational environments. This review elucidates the development of in situ cells and advanced energy materials that are used in energy storage (Li x FePO4, Li, NiMnCo and Li1.2 Ni0.5 Co0.1 Mn0.55 O2), energy conversion Fischer–Tropsch synthesis, energy generation (Pt/perfluorosulfonic acid, Pt/Ru and ZnO/Fe2O3) and energy saving (V2O5 and Li2.34 NiZr0.28 O x ), all of which have been examined using in situ STXM/STXM. Future advances in in situ STXM are also considered.

Development and Functionalization of Visible-Light-Driven Water-Splitting Photocatalysts

“…Furthermore, the geometric structure observed under electron irradiation in a vacuum is not necessarily the same as the geometric structure during the water-splitting reaction. Therefore, operando measurements using X-ray absorption fine-structure analysis and other techniques [ 316 ] are expected to be applied in photocatalyst studies, which will provide a deeper understanding of the geometric structure during the water-splitting reaction than available at present. Theoretical calculation for real system.…”

Scanning transmission X-ray microscopy studies of electrochemical activation and capacitive behavior of Mn3O4 supercapacitor electrodes

“…[23][24][25]27 Most of the electrochemical applications, particularly energy conversion and storage-related applications are associated with chemical reactions at the electrolyte and electrode interface. 27,28 STXM determination of the products of electrochemical reactions, along with quantitative spatial mapping, can provide a mechanistic understanding of electrochemical processes such as supercapacitor charging and discharging.…”

Confinement of Luminescent Guests in Metal–Organic Frameworks: Understanding Pathways from Synthesis and Multimodal Characterization to Potential Applications of LG@MOF Systems

“…Surprisingly, the results derived from TXM show that the actual porosity level was only 2–3 vol %, but this value has been greatly overestimated by Hg-intrusion by a factor of about ten times. Related to the above is scanning tunnelling X-ray microscopy (STXM), a spectro-microscopy technique resembling SEM/TEM imaging, but enables one to perform nanoscale chemical imaging using X-ray photons . Another 3-D imaging technique demonstrated was full-field tomographic XAS, where a defect-engineered HKUST-1 single crystal (∼50 μm) as studied to visualize its spatio-chemical heterogeneities and identify secondary phases at a resolution of ∼2 μm.…”