Electrochemical fabrication of functional metal oxides into nanoporous alumina template

초록

Electrodeposition of metal oxides such as Cu2O, ZnO has the following advantages over conventional methods ; precise control of film thickness and morphology, higher deposition rate, and simple equipment. ZnO is an n-type semiconductor and shows transparent and conductive properties. ZnO film can be electrochemically deposited by potential modulation method and the deposition process requires the generation of OH-. Considering SEM and XRD measurement of ZnO in O2 free and O2 saturated electrolyte, surface pH of substrate electrode are raised due to adsorption of hydroxide ions reduced from dissolved oxygen. In the fabrication of nano-size materials using nanoporous alumina template, pH increase due to the formation of OH- favors the dissolution of pore wall rather than the deposition of oxides. In this work, highly ordered nanoporous Al2O3 structure was fabricated and employed for the deposition of functional metal oxides. In the formation of nano rods of metal oxides, both chemical and electrical parameters were controlled to fill the nanopores uniformly. pH inside pores was controlled by the applied current/potential modulation and the maintenance of pH below critical value was important in the synthesis of oxide structure.