Abstract:

In order to improve photocatalytic activity and acid-resistant alkalinity of ZnO and expand the absorption range of light, nanosized ZnO particles doped with Gd³⁺ (Zn_1-xGd_xO₂(x=0~0.1)) were synthesized by thermal decomposition of the coordinated precursor, in which ethylenediamine tetraacetic acid(H₄EDTA) is the ligand. Effects of the doping amount of Gd³⁺ on the structure, phase, morphology, optical properties and photo-electrical behaviors of ZnO were studied by X-ray diffraction (XRD) spectrometry, ultraviolet-visible diffuse reflection spectroscopy (UV-Vis DRS), Fourier transform infrared (FT-IR) spectroscopy, flurescence spectroscopy (FL), scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS), dynamic photoelectrical current curve (i-t), etc. XRD results show that when the amount of Gd³⁺ is below 3%, there is a single phase of ZnO with hexagonal wurtzite structure. With the increase of Gd³⁺ doping(>3%), a little bit of second phase of Gd₂O₃ shows up and the grain size of ZnO is reduced. From i-t results, Gd³⁺ doping amount of 1% exhibits the biggest current density of 10 mA/m². With the increase of Gd³⁺ doping, the band structure of ZnO is changed, the value of conduction band (CB), valence band (VB) and band-gap value (E_g) of ZnO are all reduced. At the same time, photo-degradation results of methyl orange (MO) reveal that Gd³⁺ doping can enhance the photocatalytic activity of ZnO, and the suitable amount is 1%. The catalytic selectivity and acid-resistant alkalinity of ZnO and Gd-doped ZnO were also studied simply.

Key words: ZnO, photo-catalysis, Gd³⁺, doping, photoelectric response