La/Ce-codoped Bi2O3 composite photocatalysts with high photocatalytic performance in removal of high concentration dye.

A series of La/Ce-codoped Bi2O3 composite photocatalysts were fabricated via hydrothermal-calcination process. The as-prepared products were intensively characterized by some physicochemical characterizations like N2 physical adsorption, X-ray powder diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), UV-Vis diffuse reflectance (UV-Vis DRS), Fourier transform infrared spectroscopy (FT-IR), photoelectrochemical measurements, and photoluminescence (PL) spectroscopy. The characterization results indicated that La and Ce doping induced obvious crystal phase transformation in Bi2O3, from monoclinic to tetragonal phase. La and Ce codoping also gave rise to the obvious synergetic effects, e.g., the lattice contraction of Bi2O3, the decrease of crystal size and the increase of surface area. The photocatalytic performance of the prepared catalysts was evaluated by removal of dye acid orange II with high concentration under visible light irradiation. Results showed that La/Ce-codoped Bi2O3 displayed much higher photocatalytic performance than that of bare Bi2O3, single La or Ce doped Bi2O3 samples. The superior photocatalytic activity was mainly attributed to the improved texture and surface properties and the synergistic effects of La and Ce codoping on suppressing the recombination of photo-generated electrons (e(-)) and holes (h(+)).