Novel nano-photocatalysts of Bi and Ce oxides

Abstract In this work, Bi 2 O 3 /CeO 2 nano-spheres, aiming to act as photocatalysts for treating organic pollutants in aqueous solutions, were synthesized by a simple hydrothermal-reaction method. The produced materials were characterized by x-ray diffraction, field emission scanning electron microscopy, ultraviolet and visible spectroscopy (UV–vis), and Fourier transform infrared spectroscopy. The 3% and 9% Bi 2 O 3 doped materials were crystallized in the fluorite CeO 2 crystal structure, where an angular shift of ∼0.17° was observed in the (111) and (200) planes of CeO 2 . The crystallite sizes were calculated as 10.98 and 11.90 nm for 3% and 9% Bi 2 O 3 :CeO 2 , respectively, compared to the larger sizes of 24.4 and 13.39 nm for pure Bi 2 O 3 and CeO 2 . The surface morphology of CeO 2 nanoparticles doped with 9% Bi 2 O 3 is smooth and uniform, like the particles of pure CeO 2 powder, whereas pure Bi 2 O 3 powder particles exhibit a nonuniform morphology. The bandgap energy of the 3% and 9% Bi 2 O 3 :CeO 2 nanocomposites was 2.54 and 2.44 eV, respectively, which are lower than the bandgap energy of pure Bi 2 O 3 (2.69 eV) and pure CeO 2 (2.57 eV). The experimental results of their photocatalytic activity, tested by methylene blue degradation in aqueous solution, were very promising. The first principles calculations have been employed to provide a solid support to our experimental findings for Bi-doped CeO 2 which shows promising results.