Effect of Ag and Au doping on the photocatalytic activity of TiO2 supported on textile fibres
- PDF / 4,093,387 Bytes
- 7 Pages / 612 x 792 pts (letter) Page_size
- 17 Downloads / 195 Views
1077-L07-20
Effect of Ag and Au doping on the photocatalytic activity of TiO2 supported on textile fibres Mohammed Jasim Uddin, Federico Cesano, Domenica Scarano, Silvia Bordiga, and Adriano Zecchina Department of Chemistry IFM and Nanostructured Interfaces and Surfaces (NIS), Centre of Excellence, University of Turin, Via P. Giuria 7, Turin, 10125, Italy ABSTRACT A simple method to develop TiO2, Ag or Au-doped TiO2 thin films on cotton textiles for advanced applications, is reported. The homogeneous TiO2 thin films have been deposited on cotton textiles by using sol-gel method at low temperature (100° C), whereas Ag and Au nanoparticles were then deposited on the pre-existent TiO2 films by photoreduction. The Ag/TiO2 covered cotton fibres show multichromic behaviour (grey colour under visible light and brown colour upon ultraviolet light exposure) as well as photoactivity. The Au/TiO2 film coated the cotton textile produces a purple colour with excellent self cleaning properties. The original and treated fibres have been characterized by several techniques (SEM, HRTEM, FTIR, Raman, UV–vis spectroscopy and XRD). INTRODUCTION Nanosized anatase TiO2 is known to have a wide range of applications in photocatalysis1. The optical properties and the photocatalytic activity of TiO2 coatings do not depend only on the phase, but also on the crystallite size and porosity. The only drawback of TiO2 is that its band gap lies in the near-UV of the electromagnetic spectrum: 3.2 eV (285 nm) and 3.0 eV (410 nm) for anatase and rutile, respectively. As a consequence, only UV light is able to create electronhole pairs and to initiate the photocatalytic processes. It is therefore evident that any modification of the TiO2-based photocatalysts, resulting in a lowering of its band gap or in the introduction of stable optical sensitizers, is representing a breakthrough in the field2. An exhaustive analysis of the different approaches used to dope TiO2 is beyond of scope of this contribution. One case is doping TiO2 with various transitions metals such as Au, Ag, Pt, Cr, Nb, V, Mn, and Fe3-8. Brook et al.9 have described that Ag/TiO2 films are not only active as disinfectants but also exhibit “self-regeneration” capability, because they both kill bacteria present on the film surface and photo-degrade the residues. Recently, it has been shown that Ag/TiO2 films on pyrex glass show also multicolor photochromism and photoinduced conversion of Ag nanoparticles due to surface plasmon resonance effects10. A maximum in the photocatalytic activity with the Au-modified samples has been registered in case of 0.16 wt.% Au/TiO2. At this content the activity of the Au-modified TiO2 is approximately double that of the semiconducting support11, 12. For the reasons briefly mentioned above, we became interested in modifying the light absorbing property and antibacterial activity of Au/TiO2 and Ag/TiO2 films covering the cotton fabrics. To check the reuse of the Ag/TiO2 and Au/TiO2 covered fibres, multiple adsorption–photodegradation cycles have been perfor
Data Loading...
