Solvothermal synthesis of nano-CeO₂ and degradation of dye in indoor lighting

Azo dyes are an abundant class of synthetic, organic compounds containing one or more azo bonds (-N=N-). A large amount of these dyes are produced for using in different applications. However, their complex structure makes them difficult to biologically degrade. We sought to degrade acid orange 7 (AO7) using nitrogen-doped (N-doped) and carbon-nitrogen (C-N) co-doped nano-CeO ₂. N-doped monocrystalline CeO₂ nanoparticles was synthesised by solvothermal method using triethanolamine as a nitrogen source at 120C for 24 h. C-N co-doped monocrystalline CeO₂ nanoparticles were synthesised by solvothermal method using hexamethylenetetramine as both nitrogen and carbon source at 140C for 24 h. For purposes of comparison, a sample of undoped CeO₂ was synthesised using the dopant of neither triethanolamine nor hexamethylenetetramine. The doped and undoped CeO ₂ monocrystals were all less than 10 nm in diameter. Nitrogen and carbon-nitrogen were shown to be incorporated into CeO₂ lattice from the results of both XRD and X-ray photoelectron spectroscopy analyses. The degradation of AO7 in water was investigated using a domestic 10 W compact fluorescent lamp. The results showed the degradation ratios of AO7 in the presence of nano-CeO₂ in the sequence of: C-N co-doped CeO ₂ < N-doped CeO₂ < undoped CeO₂, corresponding to magnitudes of 98.8%, 97.6%, and 48.2%, respectively.