Preparation of La doped ZnO ceramic nanostructures by electrospinning–calcination method: Effect of La3+ doping on optical and photocatalytic properties

摘要： Ceramic nanostructures of ZnO doped with La3+ ions (0.02%, 1%, 2% and 4%) were prepared by electrospinning-calcination method. Polyvinylpyrrolidone (PVP) was used as an additional polymer to promote the electrospinning. And, the intermediate electrospun products were processed thermically at 700 °C for 3 h. The produced materials were characterized morphologically and structurally by using scanning/transmission electron microscopy (SEM/TEM) and X-ray diffraction (XRD). The XRD patterns showed the successful incorporation of La ions in the hexagonal wurtzite structure of ZnO. Optical band gaps of these ceramic nanostructures were estimated from reflectance data using Kubelka-Munk theory and were found to vary from 2.589 to 2.889 eV, depending on La3+ doping concentration. Photoluminescence spectra of undoped/doped ZnO with different contents of La3+ ion were investigated. The decay curves for the La3+ ion doped ZnO nanostructures were measured and the average lifetime was found to increase from 2.69 to 2.80 ns when La3+ content increased from 0 to 4%. The photocatalytic activity of doped products (ZnO:La) was investigated by using Congo-Red dye as a probe molecule for degradation under UV-light. Maximal color removal efficiency (97.63%) was observed experimentally for ZnO doped with 2% La3+ in dosage of 0.283 g/L. Finally, the recovered catalyst was thermally activated at 700 °C (1 h) and then successfully reused for the dye photodegradation.