Guojun Du

One-dimensional single-crystalline Ti-O based nanostructures: properties, synthesis, modifications and applications

Recent advances in the properties, synthesis, modifications and applications of one-dimensional single-crystalline Ti–O based nanostructures (including nanotubes, nanobelts, nanowires, and nanorods) are reviewed. The physical and chemical properties of one-dimensional nanostructured titanates, such as adsorption, stability, ion-exchange, optical, and proton conductivity properties, are described in connection with a particular application. The experimental parameters, morphologies, and mechanism of formation of one-dimensional nanostructured titanates produced by the alkaline hydrothermal method are critically discussed. Current progress in the modifications of one-dimensional single-crystalline Ti–O based nanostructures are discussed together with their improved performances. Examples of applications of one-dimensional nanostructured titanates in photocatalysis, lithium batteries, sensors, hydrogen production and storage, solar cells and biomedicine are presented.

Enhancement of Ethanol Vapor Sensing of TiO2 Nanobelts by Surface Engineering

TiO(2) nanobelts were prepared by a hydrothermal process, and the structures were manipulated by surface engineering, including surface coarsening by an acid-corrosion procedure and formation of Ag-TiO(2) heterostuctures on TiO(2) nanobelts surface by photoreduction. Their performance in the detection of ethanol vapor was then examined and compared by electrical conductivity measurements at varied temperatures. Of the sensors based on the four nanobelt samples (TiO(2) nanobelts, Ag-TiO(2) nanobelts, surface-coarsened TiO(2) nanobelts, and surface-coarsened Ag-TiO(2) nanobelts), they all displayed improved sensitivity, selectivity, and short response times for ethanol vapor detection, in comparison with sensors based on other oxide nanostructures. Importantly, the formation of Ag-TiO(2) heterostuctures on TiO(2) nanobelts surface and surface coarsening of TiO(2) nanobelts were found to lead to apparent further enhancement of the sensors sensitivity, as well as a decrease of the optimal working temperature. That is, within the present experimental context, the vapor sensor based on surface-coarsened Ag-TiO(2) composite nanobelts exhibited the best performance. The sensing mechanism was interpreted on the basis of the surface depletion model, and the improvement by oxide surface engineering was accounted for by the chemical sensitization mechanism. This work provided a practical approach to the enhancement of gas sensing performance by one-dimensional oxide nanomaterials.

Nanoheterostructures on TiO2 nanobelts achieved by acid hydrothermal method with enhanced photocatalytic and gas sensitive performance

Nanoheterostructures of TiO2 nanoparticles/TiO2 nanobelts and Ag/TiO2 nanoparticles/TiO2 nanobelts are prepared by the acid-assisted hydrothermal method followed by an in situ photo-reduction process. The experimental parameters, including acid corrosion time and calcination temperature, are investigated in detail. Compared with TiO2 nanobelts, the single nanoheterostructure TiO2 nanoparticles/TiO2 nanobelts have a better photocatalytic activity. The double nanoheterostructure Ag/TiO2 nanoparticles/TiO2 nanobelts can further dramatically enhance photocatalytic properties of TiO2 nanobelts. The mechanisms for formation of the heterostructure and the enhanced photocatalytic effect of the heterostructure are discussed. The liquid continuous-flow photocatalysis based on TiO2 nanobelt nanopaper with different heterostructures is carried out, which has an efficient photocatalytic ability. At the same time, the obtained TiO2 nanobelt heterostructures have a good gas sensitive performance for ethanol.

Nanopaper based on Ag/TiO2 nanobelts heterostructure for continuous-flow photocatalytic treatment of liquid and gas phase pollutants

The Ag/TiO(2) nanobelt heterostructures were prepared by the acid-assisted hydrothermal method followed by an in situ photo-reduction process. The photocatalytic activity of TiO(2) nanobelts was evidently enhanced by the heterostructures between Ag nanoparticles and TiO(2) nanobelts. The nanopapers based on Ag/TiO(2) nanobelt heterostructures were fabricated via a modified paper-making process. A novel continuous photocatalytic reactor was designed, and MO removal rate of Ag/C-TiO(2) nanopaper was achieved to 100% in 40 min for single layer and only in 6 min for three layers. The self-supported TiO(2) nanopapers with porous structures also showed an excellent continuous photocatalytic performance for toluene gas under UV light irradiation, and the corresponding degradation rate was 69.5% in 184 min. Moreover, the Ag/TiO(2) nanobelts nanopaper showed a good antibacterial effect. The multifunctional TiO(2) nanopapers modified by the heterostuctures could have potential applications in the environmental and biomaterial fields.