Enhanced photocatalytic activity of cobalt-doped titanate nanotube heterostructures decorated with Cu2O-CuO nanoparticles for organic pollutant degradation under UV and visible irradiation

In this work, Co-doped titanate nanotubes decorated with Cu2O/CuO nanoparticle heterostructures (TNTs-Co-Cu) were successfully synthesized by hydrothermal method followed by an impregnation method. The photocatalysts were characterized by TEM, XRD, Raman spectroscopy, XPS, N-2 adsorption/desorption, DRS, and Photoluminescence. The results confirm the success of the TNTs-Co-Cu heterojunctions synthesis and the excellent absorption exhibited in the visible light region. Furthermore, the photocatalytic activity of the TNTs-Co-Cu materials was higher than that of pure titanate nanotubes (TNTs) and doped with cobalt (TNTs-Co) for Methyl Blue (MB) photodegradation under UV and visible light irradiation. The improved photocatalytic activity may can explained due to the increased the lifetime of photogenerated electron/hole pairs. The photocatalytic mechanism study suggested that the photogenerated electrons in conduction band (CB) of the Cu2O flow through the CuO CB to CB of TNTs-Co, whereas the photogenerated holes migrate in the opposite direction. These transfers result in the production of O-center dot(2)- and (OH)-O-center dot radicals to promote the photooxidation reaction of MB. This study provides the understanding on the heterojunction mechanism of the MB photodegradation by TNTs-Co-Cu under UV irradiation and shows their high photocatalytic activity after 5 cycles, which make the TNTs-Co-Cu a promising photocatalyst for the multifunctional heterogeneous photocatalysis applications.