Characterization of cobalt oxide thin films prepared by a facile spray pyrolysis technique using perfume atomizer

Cobalt oxide (Co3O4) thin films were prepared by a facile spray pyrolysis technique using perfume atomizer from aqueous solution of hydrated cobalt chloride salt (CoCl2·6H2O) as source of cobalt. The films were deposited onto the amorphous glass substrates kept at different temperatures (300–500 °C). The influences of molar concentration of the starting solution and substrate temperature on the structural, morphological and optical properties of (Co3O4) thin films were studied. It was found from X-ray diffraction (XRD) analysis that the films prepared with molar concentration greater than 0.025 M/L were polycrystalline spinel type cubic structure. The preferred orientation of the crystallites of these films changes gradually from (6 2 2) to (1 1 1) when the substrate temperature increases. By Raman spectroscopy, five Raman active modes characteristic of Co3O4 spinel type cubic structure were found and identified at 194, 484, 522, 620 and 691 cm−1. The scanning electron microscopy (SEM) images showed micro porous structure with very fine grains less than 50 nm in diameter. These films exhibited also a transmittance value of about 70% in the visible and infra red range.

► Co3O4 thin films show a micro porous structure.
► Co3O4 thin films are formed with spherical grains less than 50 nm in diameter.
► The porous structure of Co3O4 films is expected to have promising application in electrochromism.