Fabrication of CNTs-Ag-TiO₂ ternary structure for enhancing visible light photocatalytic degradation of organic dye pollutant

In order to improve the catalytic efficiency of titanium dioxide (TiO₂) under visible light, TiO₂ nanoparticles was composed with the silver-covered carbon nanotubes (CA) to form CNTs-Ag-TiO₂ (CAT) ternary structure via in situ reduction combined with sol-gel method. The composite was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), diffuse reflectance spectra (DRS) and photoluminescence (PL) spectra. Using methylene blue (MB) as the model pollutant, photocatalytic activity of CAT was studied to investigate the influence of the composited amount of CA on the effect of photocatalysis. The results revealed that the photocatalytic activity of TiO₂ under both visible light and UV light were improved by compositing with CA. When the mass ratio of CA is 15%, the degradation rare of methylene blue (MB) by CAT reached to 80.8% under visible light in 3 h, which is 16.5 times higher than that of TiO₂. Accordingly, the degradation rate reached to 99.2% under UV light in 40 min, which is nearly twice as fast as that of TiO₂.