Cross-Validated Identification of Oxygen Vacancies in Co3O4 Catalysts: A Multi-technique Perspective

Oxygen vacancies in spinel Co 3 O 4 are key defects that regulate surface adsorption, redox properties and catalytic activity in oxidation reactions. This Perspective systematically examines the formation mechanisms of oxygen vacancies in Co 3 O 4 , together with a comprehensive evaluation of their characterization by FT-IR, Raman spectroscopy, electron paramagnetic resonance (EPR), X-ray photoelectron spectroscopy (XPS), and H 2 -temperature-programmed reduction (H 2 -TPR). Oxygen vacancies originate from charge-compensated removal of lattice oxygen, which is accompanied by the partial reduction of Co 3+ to Co 2+ . By correlating spectroscopic fingerprints with redox behavior, the role of lattice distortion, Co-O bond weakening, and surface reduction in identifying O V -related structural and electronic changes is clarified. The advantages and limitations of different characterization techniques are critically evaluated, providing practical guidelines for defect engineering and reliable identification of oxygen vacancies in Co 3 O 4 -based catalysts.