Layer-by-layer Self-assembly Polyurethane/TiO2 NPs Hybrid Film and Its Photocatalytic Efficiency for Decolorization of Methyl Blue

In this study, Layer-by-layer (LbL) self-assembly technique was used to fabricate TiO2 films onto glass slides. Polyurethane (PU) was used as a substrate for the immobilization of TiO2, to increase the adsorption ability of the photocatalyst. The LBL sequence was (PU/TiO2 NPs)n (n is the number of bilayers). These LbL hybrid films were characterized by Raman spectra, which confirmed the formation of TiO2 nanoparticles (TiO2 NPs) in the anatase phase with average size around 30 nm. The thickness of the film estimated around 1.1±0.2 µm as determined by scanning electron microscopy (SEM). UV-vis spectra confirmed the linear and regular growth of the films with the number of bilayers. The photocatalytic property of the films was investigated by the decomposition of methyl blue (MB) under UV-light irradiation. Furthermore, the reusability studies revealed that the fabricated film could be repeatedly used for up to six times without affecting the photocatalytic activity. In addition, the corresponding mechanism of enhanced photocatalytic activity was proposed on the basis of the investigated results from reactive species scavenging of (PU/TiO2 NPs)10. The active species h+ played the most important role in the photocatalytic reaction. This work manifested that the LbL films can be handled more easily than TiO2 NPs in suspension form. Therefore, as-synthesized film is a promising candidate in wastewater treatment application.