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)/TiO 2 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 TiO 2 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/TiO 2 , which was 4.04, 2.05 and 1.33 times higher than using TiO 2 , Mt/TiO 2 and SWCNTs/TiO 2 , 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-TiO 2 /SWCNTs composite was ~ 4 folds higher than using pristine TiO 2 . In addition, heterojunction composite retained stable and excellent photocatalytic 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.