Raman spectroscopy-in situ characterization of reversibly intercalated oxygen vacancies in α-MoO3

Abstract

This work reports on the in situ strategy to reversibly generate or suppress oxygen vacancies on α-MoO₃ which were probed by Raman spectroscopy. Reversible changes in two features of the α-MoO₃ Raman spectrum could be correlated to the generation of oxygen vacancies: displacement of the T_b band frequency and the intensity decrease of the symmetrical stretching (ν_s) band. These two features could be used to qualitatively describe oxygen vacancies. Raman results also indicate that oxygen vacancies are located in the interlayer region of the α-MoO₃ lattice. This observation is corroborated by in situ X-ray diffraction, which also indicates the absence of nonstoichiometric phase transitions.