Hydrophilic Cu2O nanostructured thin films prepared by facile spin coating method: Investigation of surface energy and roughness

We demonstrate a facile, uniform and large scale chemical route to synthesize the cuprous oxide (Cu2O) nanostructured thin film via spin coating technique. The samples were characterized by X-ray diffraction (XRD), atomic force microscopy (AFM), simultaneous thermal analysis (STA) and UV-visible spectra. Based on the results, the transparent Cu2O thin films were formed at the low temperature (275 degrees C) due to employed N-2 atmosphere in annealing processes. The average roughness is decreased by increasing the number of layers from 11 to 6.4 nm for 1 and 5 times of successive deposition of copper oxide, respectively. Afterward, by increasing the cycle of deposition, the roughness increased (similar to 87%) owning to the transformation of the growth mechanism of thin films from Volmer-Weber to Stranski-Krastanov mode. Moreover, the prepared films were extremely hydrophilic with water contact angle about 45 degrees and surface energy 54.26 mJ m(-2) after 10-cycle coating. The smooth and low energy surface with this technique could be tailored for photoelectrochemical applications such as water splitting. (C) 2014 Elsevier B.V. All rights reserved.