Electrochemical Deposition Of ZnO Nanorods And Cu₂O Thin Films

In recent years, metal oxide nanomaterials are paid much attention because of its important applications in photocatalysis, solar cells, and etc.. Zinc oxide and cuprous oxide are two typical metal oxides. Zinc oxide (ZnO) is an n-type oxide semiconductor film with a wide band gap. It has unique mechanical, optical, electrical and other properties. ZnO has become a star material world-widely due to its excellent optical, optoelectronic, and piezoelectric properties. Cuprous oxide (Cu2O) is a p-type semiconductor material which has the band gap of2.2eV. Therefore, Cu2O can produce free electrons and holes by using visible light excitation, which enables Cu2O to be effectively used for solar-electricity conversion. The nano-size and morphology of the materials have significant effects on the corresponding device performance. Thereby, it is extremely important to prepare metal oxide nanomaterials with controlled nano-size and morphology. Electrochemical deposition becomes the preferred method for preparing metal oxide materials for its simple, efficient, and cost-effective process. In this paper, we successfully obtained ZnO and Cu2O nano films by electrochemical deposition. The main conclusions drawn from experimental results and analysis are as follows:1、We prepared ZnO nanorods on FTO conductive glass substrates in three-electrode electrochemical deposition system by cathodic reduction method with Zn(NO3)2solution as the zinc source and KNO3as supporting electrolyte. The effects of different deposition parameters (concentration, deposition voltage, deposition time, etc.) on the f morphology and structure of ZnO nanorod films are investigated. The results show that changing the deposition parameters or conditions have a great effect on the morphology of nano ZnO in the electrodeposition. The optimal deposition potential is-1.0±0.1V vs. SCE, the concentration of Zn2+in aqueous solution should be around3mM. In addition, the optimized deposition temperature and the deposition time are60℃and75min respectively. We can obtain the wurtzite-type ZnO nanorods which grows along the c-axis (002) perpendicular to the on the FTO substrate pre-etched by45%HNO3with the aid of ultrasonication.2、Cu2O thin Films was prepared with three-electrode system by constant potential method. Electrolyte included a certain concentration of Cu(CH3COO)2and CF3COONa under ambient temperature and pressure. The results show that the pure phase dendritic Cu2O nanocrystals can be prepared only when the deposition potential is biased at -0.2V vs. SCE. On the contrast, Cu and Cu2O mixed nanocrystals are obtained under other conditions (such as:changes in pH, the addition of CTAB and/or NaCl, and etc.). With changing conditions, Cu2O grows along different planes, the film morphology was also varied.