Controlled deposition and enhanced visible light photocatalytic performance of Pt-modified TiO2 nanotube arrays

Highly ordered TiO2 nanotube arrays (TiO2 NTAs) have been fabricated by the potentiostatic anodization method with Ti foils. Pt nanoparticles have been successfully deposited onto TiO2 NTAs by UV light photoreduction method. In this work, X-ray diffraction, field emission scanning electron microscope, high resolution transmission electron microscopy, X-ray photoelectron spectroscopy, ultraviolet-visible spectroscopy and energy dispersive X-ray spectrometer methods were adopted to characterize the samples. The influence of different concentration of H2PtCl6 precursor solution on the morphology and photocatalytic performances of samples was discussed. The SEM observations showed that Pt nanoparticles distributed on the wall of TiO2 nanotubes uniformly. UV-vis spectra analysis showed that the light absorption of Pt/TiO2 NTAs has been extended to the visible light range. When the concentration of H2PtCl6 was 3 mM, the prepared sample showed the highest photodegradation rate. After irradiated under visible light for 2 h, the degradation rate of methyl orange solution reached 84.27%. Under the same condition, no obvious photodegradation of methyl orange was found for TiO2 NTAs. Kinetic research showed that photodegradation process followed the first-order reaction, the apparent reaction rate constant of 3 Pt/TiO2 NTAs was 1.493 × 10-2 min-1