Photoreactive TiO₂/Carbon Nanotube Composites: Synthesis and Reactivity

Abstract

Electron-hole recombination limits the efficiency of TiO2 photocatalysis. We have investigated the efficacy with which anatase/carbon nanotube (CNT) composite materials reduce charge recombination and enhance reactivity. We synthesized nanostructured assemblies composed of different proportions of anatase (5 or 100 nm) and either single-or multi-walled CNTs. The composites were prepared using a simple low temperature process in which CNTs and anatase nanoparticles were dispersed in water, dehydrated at 80 degrees C, and dried at 104 degrees C. The structures of the various TiO2/CNT composites were characterized by scanning electron microscopy (SEM) and their function was tested by phenol oxidation. Charge recombination was compared by measuring the photoluminescence spectra of select composites. We found that a nanostructured composite assembled from the 100 nm anatase and single-walled CNTs (SWCNTs) exhibited enhanced and selective photocatalytic oxidation of phenol in comparison to both pure anatase and Degussa P25. A mechanism for the enhanced reactivity is proposed in which electrons are shuttled from TiO2 particles to the SWCNTs as a result of an optimal TiO2/ CNT arrangement that stabilizes charge separation and reduces charge recombination. In addition, the SWCNT assembly provides better catalyst-support (dispersal and connection) than multi-walled CNTs.

Investigating the synergistic effects in tourmaline/TiO2-based heterogeneous photocatalysis: Underlying mechanism insights

“…5a), which would be ascribed to the radiative recombination of self-trapped excitons [28]. Peak shifts are often resulted from the electron trapping before recombination [29]. The PL results clearly revealed the efficient charge transfer of the hetero samples with increasing tourmaline content, corresponding to the emission decay profiles.…”

Preparation and Characterization of Mn/N Co-Doped TiO2 Loaded on Wood-Based Activated Carbon Fiber and Its Visible Light Photodegradation

“…Moreover, Mn/Ti-N-WACF samples showed stronger visible light absorptions than Ti-WACF. The relatively strong absorption at 400-600 nm was attributed to the co-doping of N and Mn elements into the lattice of TiO 2 [38], and the chemical bonds of Ti-O-C rendered a red shift in the photo responding range and facilitated a more efficient utilization of light for the photocatalysis [39,40]. With the Mn doping content was increased, the visible light absorbance of the Mn/Ti-N-WACF samples was initially increased and then decreased.…”

Strategies to Successfully Cross-Link Carbon Nanotubes

“…Using particles and nanocrystals as cross-linking agents is of great interest for increasing the surface area for reactivity. Examples can found in literature of the use of such constructs in the formation of photoreactive composites of CNTs and titania (Yao et al, 2008) and Pt nanoclusters/titanium dioxide nanotube composites (Dong et al, 2010). In order to increase the utility of these composites, they would need to be processed into films to fully take advantage of their unique properties.…”