Effect of lithium codoping on the structural, morphological and photocatalytic properties of Nd-doped ZnO

Nd nanoparticles (NPs) codoped with lithium at low temperature and short synthesis time were prepared using the polyol method, and the influence of different lithium contents at constant atomic concentration of Nd was evaluated. The resulting materials were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer–Emmett–Teller analysis (BET), X-ray photoelectron spectroscopy (XPS), and optical spectroscopies (photoluminescence (PL), cathodoluminescence (CL) and Raman). X-ray diffraction patterns demonstrate that the materials are polycrystalline with a wurtzite structure with no secondary phases in the concentrations evaluated. The unit cell parameters were determined, and the crystallite size was calculated considering the three most intense diffraction peaks. TEM shows that the particles are polycrystalline with no amorphization. Raman analysis further confirms the wurtzite hexagonal structure of the particles. Morphological and size studies using SEM and TEM show that the most remarkable change is the evolution from hemispherical ZnO NPs to spindle-shaped particles for Li–Nd doped ZnO. The surface chemistry, as studied by X-ray photoelectron spectroscopy (XPS), confirms the incorporation of Nd3+. The study of the photocatalytic behavior of the Li–Nd codoped ZnO NPs reveals that the ZNL0.5 sample exhibits the highest photocatalytic activity using a solution of Rhodamine B (2.5 ppm) as a reference.