Reactive sputtering deposition of Co3O4 films and an evaluation of its use as an electrochemical sensor for ascorbic acid

Co 3 O 4 films have been deposited using reactive DC magnetron sputtering onto fluorine-doped tin oxide (FTO) and fused silica (SiO 2 ). X-ray diffraction measurements confirmed the spinel Co 3 O 4 phase. The surface roughness of the films were 4 nm and 20 nm for SiO 2 and FTO substrates, respectively, as measured by atomic force microscopy. Optical transmission spectra of Co 3 O 4 films show strong absorption in the near-infrared and visible regions. The photoconductivity response of SiO 2 /Co 3 O 4 , using 405 nm excitation, measured at room temperature is much smaller than the observed at 10 K. The electrochemical activity of the FTO/Co 3 O 4 for the oxidation reaction of the ascorbic acid (AA) was investigated by differential pulse voltammetry and chronoamperometric. A model for the oxidation, based on density functional theory calculations for the electronic structure of the AA, is proposed. The set of results show that the assembled FTO/Co 3 O 4 electrode can be used as an alternative and remarkable-performance non-enzymatic device to ascorbic acid electrooxidation.