Facile method to obtain anatase and anatase-brookite nanoparticles (TiO2) with MWCNT towards reducing the bandgap

Abstract

Synthesis of TiO2 nanoparticles in anatase, and anatase-brookite phase mixture, deposited over multilwalled carbon nanotubes (MWCNT) is reported. The materials were obtained from an amorphous titania and MWCNT initial composite, using the sol-gel method at low temperature. To achieve the different crystalline phases, the initial composites were treated at different conditions: i) for the anatase phase, a thermal treatment at 400 °C was carried out, and ii) for the anatase-brookite mixture, the composite was placed in a reflux system at 80 °C during 5 h. The nominal weight percentage of MWCNT added to composites was 5%. The influence of MWCTN on the physical-chemical parameters of TiO2 was studied using diverse characterization techniques such as thermogravimetric analysis, X-ray diffraction, transmission electron microscopy, Raman and UV spectroscopies, and surface area analysis. Results indicate that the TiO2 crystal sizes of the different phases was not affected for the addition of MWCNT. Although, there was an effect on the surface area, vibrations of molecular bonds and on the band gap energy, indicating an interaction between the TiO2 nanoparticles and the carbonaceous support. Prime novelty statementThe novelty of the presented research work is the finding of a facile methodology using mild conditions (400 °C) to obtain TiO2 nanoparticles in anatase and anatase-brookite phases in a composite material with carbon nanotubes. The effect of the synthesis conditions as well as the addition of multiwalled carbon nanotubes to TiO2 particles was studied. The most significant achievement was to increase the surface area of the materials while reducing the bandgap. In addition it was possible to obtain small particle size and a well distribution of phases.