Advances in Synchrotron Radiation-based X-ray Absorption Spectroscopy to Characterize the Fine Atomic Structure of Single-atom Nanozymes.

Single-atom nanozymes (SAzymes) with high atomic utilization, excellent catalytic activities, and selectivity have recently attracted significant interest. Usually, they contain only isolated metal atoms embedded in host matrices. However, traditional measuring instruments are extremely difficult to obtain their useful structural information due to ultra-low metal loading, amorphous structure, coordination with light-weight surface atoms and/or co-existing of other metal elements. Synchrotron radiation-based X-ray absorption fine structure spectroscopy (XAFS) has demonstrated its usefulness for this type of catalyst. In this mini-review, we have summarized the recent progress using XAFS to characterize the fine atomic structure of these nanozymes. The synthetic strategies of SAzymes, the principle of XAFS, delicate structural information by XAFS, and the applications of SAzymes have been presented. Furthermore, the outlook and challenges in this active research field have also been discussed. We expect that the help of XAFS can offer a wealth of opportunities to design and develop more efficient SAzymes and apply them to various fields.