A simple strategy for the anchoring of anatase titania on multi-walled carbon nanotubes for solar energy harvesting

Pure anatase titania (TiO2) nanoparticles were anchored on the surface of functionalized multi-walled carbon nanotubes (MWCNTs) using a solution-based synthetic method at room temperature. X-ray diffraction and Raman patterns were used to analyze the structural and phase composition of these nanocomposites, highlighting the formation of anatase TiO2 nanoparticles with MWCNTs up to 0.5 wt.%. The non-spherical particles of TiO2 in the order of 7-12 nm, were confirmed through transmission electron microscopy analysis and these particles were well dispersed on the MWCNTs. The optical absorption spectra of these structures were studied by diffuse reflectance UV-visible spectroscopy. The optical energy band gap of the various nanocomposites was observed from 3.2 to 2.6 eV with an increasing amount of MWCNTs, up to 0.5 wt.%. The generation of OH species in nanocomposites in the presence of visible light irradiation was investigated by photoluminescence spectroscopy. Photoelectrochemical cell performance of TiO2-MWCNTs for 0.5 wt.% content of MWCNTs under light intensity 100 mW/cm2 showed a significant improvement of short-circuit current density from 1.23 to 12.1 mA/cm2 and a cell efficiency (0.090-3.46%) that is better than many reported anatase-based compositions without sensitizer.