(425d) Unique Preparation of TiO2 – SWCNT Nanocomposites for the Photocatalytic Conversion of Carbon Dioxide

Carbon capture, utilization, and storage (CCUS) has gained greater significance over the last decade in controlling CO₂ emissions. This work concentrates on the utilization of CO₂ (i.e. converting CO₂ into useful chemicals or hydrocarbons such as formic acid, methanol, and ethanol). The key to economically convert point-source emitted CO₂ is through low-temperature, photocatalytic reactions. In addition, materials that are activated using visible light, instead of UV, lowers the overall cost of the conversion process. Unfortunately, CO₂ conversions have remained low, particularly with visible light irradiation, for photocatalysts synthesized using conventional methods. In this work, single walled carbon nanotubes (SWCNT) and TiO₂ nanocomposites were synthesized through a photo-assisted sol-gel method with surfactants SDS and SDBS.

Preparation methods for the TiO₂ – SWCNT nanocomposite were tested to develop a material with low bad gap energies that could effectively use visible light for CO₂ conversion. Surfactants were used to separate the bundles of SWCNTs for efficient dispersion of TiO₂ onto the SWCNT surfaces. Lattice defects (i.e. oxygen vacancies and titanium defects of the TiO₂ nanoparticles) were synthesized using photo-assisted techniques for enhanced light absorption and increased separation of charge carriers. Annealing temperatures 200, 350, and 500 ËšC annealing temperatures were also tested. Material characterizations (TEM-EDX, XRD, UV-Visible spectroscopy, IR-DRS, Raman spectroscopy, and FTIR) of the TiO₂ – SWCNT nanocomposites were performed. In addition, photoelectrochemical characterization was performed on the nanocomposites to elucidate differences in the photocurrent value generated between TiO₂ nanoparticles and the nanocomposites. These results, along with CO₂ photocatalytic conversion reactions, help to inform about the efficient light-induced separation of charge carriers in the synthesized nanocomposites. The results of the synthesis, characterizations, and photocatalytic reaction testing will be presented.