Yihua Sun

Synthesis of porous Al doped ZnO nanosheets with high adsorption and photodecolorizative activity and the key role of Al doping for methyl orange removal

Porous Al doped ZnO (AZO) nanosheets have been prepared as an efficient multifunctional water treatment material. Their fundamental properties were characterized by various spectroscopic testing methods. The AZO nanosheets displayed very rapid adsorption rate and high adsorption capacity for methyl orange (MO) dye. The kinetics and equilibrium of adsorption process were found to follow the pseudo-second-order kinetic and Langmuir isotherm models, respectively. Furthermore, the AZO nanosheets exhibited superior photodecolorizative activity compared with the commercial P25 TiO2 nanoparticles. It was found that Al doping increased the zeta potential of AZO nanosheets and then significantly enhanced the adsorption capacity for MO dye and, at the same time, retarded the recombination of photoexcited electron–hole pairs, and prolonged the lifetime of the photo-generated carriers, and then improved the semiconductor photocatalytic activity. In addition, the visible-light-driven dye photosensitized degradation was also an important reason for enhanced photodecolorizative activity. Therefore, AZO nanosheets are a potential multifunctional water treatment material combining highly efficient adsorption and photocatalytic degradation.

Structural and optoelectronic properties of AZO thin films prepared by RF magnetron sputtering at room temperature

Abstract Al-doped ZnO thin films were prepared on glass substrate using an ultra-high density target by RF magnetron sputtering at room temperature. The microstructure, surface morphology, optical and electrical properties of AZO thin films were investigated by X-ray diffractometer, scanning electron microscope, UV-visible spectrophotometer, four-point probe method, and Hall-effect measurement system. The results showed that all the films obtained were polycrystalline with a hexagonal structure and average optical transmittance of AZO thin films was over 85 % at different sputtering powers. The sputtering power had a great effect on optoelectronic properties of the AZO thin films, especially on the resistivity. The lowest resistivity of 4.5×10 −4 Ω·cm combined with the transmittance of 87.1% was obtained at sputtering power of 200 W. The optical band gap varied between 3.48 and 3.68 eV.