ScholarWorks@숙명여자대학교

초록

CeO2 nanoparticles (NPs) are intrinsically UV-active but remain largely inactive under visible light owing to their wide bandgap. This study demonstrates that Ir ion doping, followed by NaBH4-assisted reduction, stabilizes a high density of oxygen vacancies (OV) in the CeO2 lattice. The induced defect states introduce mid-gap levels, narrow the optical bandgap (UV-vis/Tauc analysis), and alter the surface redox chemistry, thereby enabling pronounced visible-light photocatalytic oxidation of 2,5-hydroxymethylfurfural (HMF). In situ X-ray photoelectron spectroscopy under wavelength-controlled illumination reveals reversible changes in Ce 3d, O 1s, and OV-related features that correlate with wavelength-dependent absorption and catalytic activity. Photocatalytic reactivity is further corroborated by a fluorogenic probe assay that shows a green fluorescence turn-on upon illumination in the presence of NPs. These findings demonstrate that controlled Ir incorporation combined with NaBH4 reduction provides a targeted defect-engineering route for tuning the electronic structure and surface chemistry of CeO2 toward efficient visible-light biomass oxidation.

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