The Study On Electrochemical Deposition And Property Of ZnO Thin Film

ZnO thin film was galvanostatically electrodeposited on Cu substrate from an aqueous solution of Zn (NO₃)₂ and Cu substrate was used as a cathode. The electrodeposition process of ZnO thin film was systematically studied under different deposition conditions such as current density, electrolyte concentration, solution temperature, deposition time and ion doping. The structure, composition and optical property of deposits were characterized by X-ray diffraction (XRD), UV-Vis diffuse reflectance spectra, thermal gravimetric-differential thermal analysis (TG-DTA), infrared absorption spectra (IR) and electrochemical impedance spectra (EIS).The results indicated that the structure and composition of films were related with deposition conditions. The crystallinity of ZnO increased with the current density. Metal Zn would be deposited at low concentration of Zn (NO₃)₂ or at low solution temperature, andZns (NO₃)₂ (OH)₈ would be formed at high concentration. So 0.1M Zn (NO₃)₂ and solution temperature of 65°C were often used. Furthermore, ZnO thin films had two-layer structure , which was measured by EIS. When ZnO was doped with Cu²⁺, the absorption edge of ZnO increased from 375nm to 458nm, the bandgap energy decreased from 3.3ev to 2.7ev and the light absorption range of thin film became larger. Such phenomena were important for the optical application of ZnO thin film. ZnO thin film had single-layer structure while doped with Cu²⁺.Moreover, ZnO thin film was electrodeposited on porous Ni. A three-electrode system was composed of ZnO/Ni as the anode, Pt as the cathode and saturated calomel electrode (SCE) as the reference electrode. It was used for the electrocatalytic degradation of methylorange (MO) under anodic bias potential. The effects of potential, initial concentration of MO, concentration of supporting electrolyte and dopant on the degradation efficiency were studied.The results showed that the porous Ni was a good carrier. The degradation efficiency of MO would be improved when we changed the conditions such as increasing the anodic potential or concentration of supporting electrolyte and decreasing the initialconcentration of MO or doping.