Photoelectrochemical characterization of ITO/TiO2 electrodes obtained by cathodic electrodeposition from aqueous solution

Abstract

In the present work, the photoelectrochemical characterization of ITO/TiO2 electrodes electrosynthesized at two distinct TiO2 film charges (0.35 and 1.00 C) was performed. Scanning electron microscopy presented a globular-like nanostructure and a typical morphology that are dependent on the growing charge, where the photoelectrode synthesized at 0.35 C presented a more homogeneous morphology. Such dependence was also observed at the photoelectrochemical response, once the photoactivity for the photoelectrode synthesized at 0.35 C was better than the photoelectrode synthesized at 1.00 C, which was explained by the surface recombination process and the electron lifetime. In order to explore the charge-transfer process and the displacement of the quasi-Fermi level upon illumination, electrochemical impedance spectroscopy (EIS) was performed at distinct applied potentials. EIS results corroborate the previous results, presenting a higher charge-transfer resistance and a lower chemical capacitance for the 1.00 C electrode film, the last one in accordance with the open-circuit voltage decay.