Synthesis of Pr-doped ZnO nanoparticles: Their structural, optical, and photocatalytic properties

Undoped and praseodymium-doped zinc oxide (Pr-doped ZnO) (with 2.0-mol%-6.0-mol% Pr) nanoparticles as sunlight-driven photocatalysts are synthesized by means of co-precipitation with nitrates followed by thermal annealing. The structure, morphology, and chemical bonding of the photocatalysts are studied by x-ray diffraction (XRD), scanning electron microscopy (SEM) with energy dispersive x-ray emission spectroscopy (EDS), x-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectroscopy (FTIR), respectively. The optical properties are studied by photoluminescence (PL) and UV-vis diffuse reflectance spectroscopy (UV-vis DRS). We find that Pr doping does not change the crystallinity of ZnO; but it reduces the bandgap slightly, and restrains the recombination of the photogenerated electron-hole pairs. The photocatalytic performance of the photocatalysts is investigated by the photodegradation reaction of 10-mg/L rhodamine B (RhB) solution under simulated sunlight irradiation, showing a degradation rate of 93.75% in ZnO doped with 6.0-mol% Pr.