In-situ synthesis of TiO2 nanostructures on Ti foil for enhanced and stable photocatalytic performance

Abstract

TiO2 nanostructures with strong interfacial adhesion and diverse morphologies have been in-situ grown on Ti foil substrate through a multiple-step method based on conventional plasma electrolytic oxidation (PEO) technology, hydrothermal reaction and ion exchange process. The PEO process is critical to the formation of TiO2 seeding layer for the nucleation of Na2Ti3O7 and H2Ti3O7 mediates that are strongly attached to the Ti foil. An ion exchange reaction can finally lead to the formation of H2Ti3O7 nanostructures with diverse morphologies and the calcination process can turn the H2Ti3O7 nanostructures into TiO2 nanostructures with enhanced crystallinity. The morphology of the TiO2 nanostructures including nanoparticles (NP), nanowhiskers (NWK), nanowires (NW) and nanosheets (NS) can be easily tailored by controlling the NaOH concentration and reaction time during hydrothermal process. The morphology, composition and optical properties of TiO2 photocatalysts were analyzed using scanning electron microscope (SEM), X-ray diffraction (XRD), photoluminescence (PL) spectroscopy and UV–vis absorption spectrum. Photocatalytic tests indicate that the TiO2 nanosheets calcined at 500 °C show good crystallization and the best capability of decomposing organic pollutants. The decoration of Ag cocatalyst can further improve the photocatalytic performance of the TiO2 nanosheets as a result of the enhanced charger separation efficiency. Cyclic photocatalytic test using TiO2 nanostructures grown on Ti foil substrate demonstrates the superior stability in the photodegradation of organic pollutant, suggesting the promising potential of in-situ growth technology for industrial application.