In situ/operando Mo sec ssbauer spectroscopy for probing heterogeneous catalysis

In situ/operando Mo sec ssbauer spectroscopy is one of themost powerful techniques to quantitatively monitor the coordination and electronic structure of Mo sec ssbauer isotopes (119Sn, 57Fe, etc.) contained in heterogeneous catalysts under practical reaction conditions. To promote further progress in identifying the real structure of catalytic site(s) and revealing the underlying catalytic mechanism, herein we thoroughly summarize the recent advances of in situ/operando Mo<spacing diaeresis> ssbauer technique for probing heterogeneous catalysts and electrode materials for sustainable energy applications, including electrocatalysis, thermocatalysis, Li-ion batteries, etc. The unique role of this technique in different catalytic system is discussed with emphasis placed on several typical research advances. Moreover, the recent emerging operando Mo sec ssbauer technique for the study of single- atom catalysts, which is considered as a new eye for providing electronic-level insight into catalytic mechanism, is highlighted. Finally, the outlooks and challenges are discussed toward further application and rising influence of in situ/ operando Mo<spacing diaeresis> ssbauer spectroscopy in heterogeneous catalysis.