Montmorillonite dispersed single wall carbon nanotubes (SWCNTs)/TiO_2 heterojunction composite for enhanced dynamic photocatalytic H_2 production under visible light

摘要

Fabrication of montmorillonite (Mt) dispersed single walled carbon nanotubes (SWCNTs)/TiO2 heterojunction composite with high capacity for photocatalytic hydrogen production under visible light has been investigated. The composite samples, developed via a simple sol-gel assisted wet-impregnation method, were characterized through X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), high resolution transmission electron microscopy (HR-TEM), ultraviolet-visible spectroscopy (UV-Vis) and photoluminescence (PL) spectroscopy. The synergistic effects between Mt/SWCNTs coupled TiO2 ternary composite exhibited excellent performance for H-2 production in a slurry type photoreactor system using methanol-water mixture under visible-light irradiations. The highest H-2 yield rate of 9780 ppm h(-1) g(-1) was achieved over SWCNTs/Mt/TiO2, which was 4.04, 2.05 and 1.33 times higher than using TiO2, Mt/TiO2 and SWCNTs/TiO2, respectively. This significantly enhanced performance can be attributed to synergism effects between SWCNTs and Mt for transporting charge carrier with their hindered recombination. Furthermore, impressively high H-2 photocatalytic activity was achieved with methanol-water mixture at pH 7, which was 6.77 times higher than using water splitting process. The apparent quantum yield obtained over the Mt-TiO2/SWCNTs composite was similar to 4 folds higher than using pristine TiO2. In addition, heterojunction composite retained stable and excellent photo catalytic performance for H-2 formation up to three cyclic runs. Thus, designing highly efficient, noble metals-free and low cost photocatalyst can offer a promising way for H-2 generation under solar energy to encounter environmental pollution.