Enhancement of surface areas of Co3O4 and NiCo2O4 electrocatalysts prepared by spray pyrolysis

Nickel and cobalt cobaltites have been prepared as thin films by spray pyrolysis of solutions containing cobalt and nickel nitrates. An alkali nitrate has been added to the sprayed solution which remained undecomposed during the formation of the oxide film. Then, this alkali nitrate dissolved leading to an enhancement of the roughness of the films which can be controlled, We report herein the preparation and characterization of such films by X-ray diffraction, FTIR reflectance spectroscopy, scanning electron microscopy and electrochemical methods, The roughness factors have been determined by cyclic voltammetry. An increase of the roughness, up to ten times, has been observed, The stationary I-E curves are representative of the good correlation between the magnitude of the currents obtained and the roughness factors. Owing to experimental evidence and considering the low preparation temperature, we have rejected the possibility of incorporation of the alkali ions in the crystalline lattice.