TiO2 Nanoparticles Wrapped with Short Single Wall Carbon Nanotubes for Enhanced Photocatalytic Performance

The interfacial contact between TiO₂ and carbon-related structures is crucial in monitoring electron transfer rate and, in turn, the photocatalytic efficiency. Herein, we report a facile approach to wrap short single wall carbon nanotubes (SWCNTs) on TiO₂, with improved heterojunctions and delayed charge carrier recombination. Ultrasonication-assisted cutting was utilized to cut long SWCNTs (1 – 3µm in length) to short SWCNTs (50-400 nm in length). The short SWCNTs were wrapped on TiO₂ nanoparticles (100 nm) via a hydration-condensation technique. The synthesized nanostructures were characterized by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and photoluminescence spectroscopy. In comparison to traditional TiO₂-SWCNT composites, TiO₂ wrapped by short-SWCNTs showed longer lifetimes of photogenerated electrons and holes, as well as a higher photocatalytic activity in gas-phase degradation of acetaldehyde. In addition, upon comparison with a TiO₂-nanographene "quasi-core-shell" structure, TiO₂-SWCNT structures offer better electron capturing efficiency and higher photocatalytic performance, revealing the impact of the dimensions of graphitic structures on the interfacial transfer of electrons and light penetration to TiO₂. The engineering of TiO₂-SWCNT structure is expected to benefit photocatalytic degradation of other volatile organic compounds, and may provide alternative pathways to further improve the efficiency of other carbon-based photocatalysts.