Chemical bath co-deposition of Co3O4 and In2O3 on TiO2 nanotubes, aiming for photoanodes with improved photoelectrochemical properties

Abstract

This study investigates the implications of the deposition of Co3O4 and In2O3 onto TiO2 nanotube thin films for the photoelectrochemical activity of TiO2 nanotubes (TNTs). Initially, TiO2 nanotubes were fabricated through an electrochemical anodizing process. Subsequently, a facile chemical bath deposition (CBD) method was used to deposition Co3O4 and In2O3 oxides. The resulting composites are used as photoanodes for the photoelectrochemical cathodic protection of AISI304 stainless steel (304SS) in marine environments. The surface morphology, compositions, crystalline structures, and optical characteristics of samples were examined using a combination of FESEM, TEM, EDX, XPS, XRD, and UV-Vis absorption spectroscopy. Electrochemical measurements under both illuminated and dark conditions were conducted to assess the photoelectrochemical characteristics of synthesized samples. The optimal co-deposited photoanode, significantly shifted the open circuit potential of the coupled AISI 304SS to −708 mV under intermittent light exposure, demonstrating appropriate photocathodic protection (PCP) performance. This potential was further enhanced and maintained at −720 mV for an hour in continuous light tests. Additionally, the photoanodes showed some degrees of delayed cathodic protection even after the light was switched off. The Co3O4-In2O3-modified TNTs composite exhibits superior photoelectrochemical cathodic protection activity due to the synergistic effects of Co3O4 and In2O3 nanoparticles.