Fabrication and photocatalytic activities of dark brown CeO2 with a crystalline-core/disordered-shell heterostructure

Dark brown ceria, CeO2, with excellent photocatalytic properties, was synthesized by constructing a crystalline-core/disordered-shell heterostructure using NaBH4 reduction. The structure, crystallinity and morphology of the as-prepared samples were characterized using x-ray diffraction, transmission electron microscopy, and high-resolution transmission electron microscopy. The x-ray photoelectron spectra confirm a high concentration of Ce3+ and oxygen vacancies in the CeO2 sample. The dark brown compound shows excellent properties especially with respect to solar-energy absorption but also the transfer and separation of charge carriers-due to its heterostructure-related features. The photocatalytic activity of the treated samples is obviously higher than that of pure CeO2 and reaches the maximum with Ce3+/Ce molar ratio of 51.7%.