Montmorillonite dispersed single wall carbon nanotubes (SWCNTs)/TiO2 heterojunction composite for enhanced dynamic photocatalytic H2 production under visible light

Abstract

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 H2 production in a slurry type photoreactor system using methanol-water mixture under visible-light irradiations. The highest H2 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 H2 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 ~ 4 folds higher than using pristine TiO2. In addition, heterojunction composite retained stable and excellent photocatalytic performance for H2 formation up to three cyclic runs. Thus, designing highly efficient, noble metals-free and low cost photocatalyst can offer a promising way for H2 generation under solar energy to encounter environmental pollution.