Multifunction applications of Bi2O3:Eu3+ nanophosphor for red light emission and photocatalytic activity

Undoped and Eu3+ doped Bi2O3 nanophosphors were synthesized by a citrate sol-gel method. Polyethylene glycol (PEG) was used as a surfactant to control the particle sizes. The obtained nanoparticles were characterized by powder X-ray diffraction (PXRD), field emission scanning electron microscopy, X-ray photoelectron spectroscopy (XPS), diffuse reflectance, photoluminescence (PL) and photocatalytic activities. The crystal structure and purity of the synthesized samples were investigated by PXRD and it exhibited the monoclinic (a) single phase of Bi2O3. The high content Eu3+ (1.5 and 2 mol%) doped samples consisted of a mixed phase of monoclinic (a) and tetragonal (beta) Bi2O3. The crystallite size was determined by the Scherrer equation and it was found to be in the range of 50-97 nm. The particles were irregular, agglomerated and of spherical nature and the PEG covered the surface of the undoped and Bi2O3:Eu3+ particles. XPS indicated that the Bi 4f spectrum contained a doublet, which is assigned to the Bi3+ oxidation state. The reflectance study confirmed the decrease in the bandgap for the doped samples. PL emission, with an intense red peak at 612 nm and other peaks at 581, 592, 652 and 707 nm was observed under different excitations of 466, 528 and 534 nm. These characteristic emissions were assigned to the luminescence of Eu3+ centers due to the 5D0. 7FJ (J= 0, 1, 2, 3, 4) transitions, respectively. The photocatalytic activities of the undoped and Bi2O3:Eu3+ nanomaterials were evaluated for the degradation of Rhodamine B (RhB) under UV-Vis irradiation. The results showed that Bi2O3:Eu3+ (0.6 mol%) had a better photocatalytic activity compared to the undoped sample.