Fabrication of swcnts modifiedtio2 nanocomposite towards enhanced photocatalytic carbon dioxide reduction to fuels under visible light

Abstract

In this study, fabrication of single wall carbon nanotubes modified titanium dioxide (SWCNTs/TiO2) composite catalyst for selective and enhanced photocatalytic CO2 reduction to fuels has been investigated. The samples were synthesized by a modified one-pot sol-gel method and were characterized by X-ray diffraction (XRD), Scanning Electrons Microscopy (SEM) and Photoluminescence (PL) Spectroscopy. The pure anatase phase with reduced crystal size and hindered charges recombination was obtained by modifying TiO2 with SWCNTs. The performance of newly developed nano-catalyst was investigated for photo-induced CO2-hydrogen reduction under visible light irradiations. The products detected were CO, CH4 and CH3OH with appreciable amounts of C2-C3 hydrocarbons. The yield of CO as the main product over 5 wt% SWCNTs/TiO2 was 1,220 µmole g-cat.-1 h-1, a 5.35 times more than the pure TiO2 NPs. Similarly, yield of methanol of 23.4 µmole g-cat.-1 h-1 was detected, 6.5 folds the amount produced over the pure TiO2 NPs. The SWCNTs found to be efficient to enhance TiO2 activity due to its ability to capture visible light irradiations with proficient charges separations over the TiO2 surface. The higher interaction between SWCNTs/TiO2, efficient adsorption-desorption and hindered charges recombination rate promoted the photoactivity and products selectivity. The reaction mechanism to understand the role of SWCNTs in TiO2 for CO2-hydrogen conversion is also deliberated.