Verifying the relationships of defect site and enhanced photocatalytic properties of modified ZrO 2 nanoparticles evaluated by in-situ spectroscopy and STEM-EELS

Base treatment and metal doping were evaluated as means of enhancing the photocatalytic activity of ZrO 2 nanoparticles (NPs) via the generation of oxygen vacancies (O vS ), and the sites responsible for this enhancement were identified and characterized by spectroscopic and microscopic techniques. We confirmed that O vS produced by base treatment engaged in photocatalytic activity for organic pollutant degradation, whereas surface defects introduced by Cr-ion doping engaged in oxidative catalysis of molecules. Moreover, we verified that base-treated ZrO 2 NPs outperformed their Cr-ion doped counterparts as photocatalysts using in situ X-ray photoelectron spectroscopy and scanning transmission electron microscopy coupled with electron energy loss spectroscopy (STEM-EELS). Thus, our study provides valuable information on the origin of the enhanced photocatalytic activity of modified ZrO 2 NPs and demonstrates the practicality of in situ spectroscopy and STEM-EELS for the evaluation of highly efficient metal oxide photocatalysts.