Synthesis, characterization and application of semiconducting oxide (Cu2O and ZnO) nanostructures

In the present study, we report the synthesis, characterization and application of nanostructured oxide materials. The oxide materials (Cu2O and ZnO) have been synthesized by electrolysis based oxidation and thermal oxidation methods. Cuprous oxide (Cu2O) nanostructures have been synthesized by anodic oxidation of copper through a simple electrolysis process employing plain water (with ionic conductivity, similar to 6 mu S/m) as electrolyte. In this method no special electrolytes, chemicals and surfactants are needed. The method is based on anodization pursuant to the simple electrolysis of water at different voltages. Two different types of Cu2O nanostructures have been found. One type got delaminated from copper anode and was collected from the bottom of the electrochemical cell and the other was located on the copper anode itself. The nanostructures collected from the bottom of the cell are either nanothreads embodying beads of different diameters, similar to 10-40 nm or nanowires (length, similar to 600-1000 nm and diameter, similar to 10-25 nm). Those present on the copper anode were nanoblocks with preponderance of nanocubes (nanocube edge, similar to 400 nm). The copper electrode served as a sacrificial anode for the synthesis of different nanostructures. Aligned ZnO nanorod array has been successfully synthesized by simple thermal evaporation catalyst free method. Detailed structural characterizations revealed that the as synthesized aligned ZnO nanorods are single crystalline, with a hexagonal phase, and with growth along the [0001] direction. The room-temperature photoluminescence spectra showed a weak ultraviolet emission at 380 run, a broad blue band at 435 nm and a strong orange-red emission at 630 nm. Structural/microstructural characterization of these nanomaterials have been carried out employing scanning (XL-20) and transmission electron microscopic (Philips EM, CM-12 and Technai 20G(2)) techniques and X-ray diffraction techniques having graphite monochromater with CuK alpha radiation (lambda = 1.54439 angstrom) (X'Pert PRO PAN analytical). The UV-visible absorption spectra were recorded on Model-VARIAN, Cary 100, and Bio UV-visible spectrophotometer. The photoluminescence (PL) measurement was carried out at room temperature with a He-Cd, a laser excited at 325 nm.