Fabrication of Rh-doped TiO 2 nanofibers for Visible Light Degradation of Rhodamine B
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Fabrication of Rh-doped TiO2 nanofibers for Visible Light Degradation of Rhodamine B Emilly A. Obuya1, William Harrigan1, Tim O’Brien1, Dickson Andala2, Eliud Mushibe1 & Wayne E. Jones Jr1*. 1
Department of Chemistry, State University of New York at Binghamton, 4400 Vestal Parkway East, Vestal, NY 13902, USA. 2 Department of Chemical Engineering, Pennsylvania State University, 25 Fenske, University Park, PA 16802, USA. *Author to whom correspondence should be addressed; e-mail; [email protected]; Tel: +1-607-777-2421; Fax: +1-607-777-4478. ABSTRACT The synthesis and application of environmentally benign, efficient and low cost heterogeneous catalysts is increasingly important for affordable and clean chemical technologies. Nanomaterials have been proposed to have new and exciting properties relative to their bulk counterparts due to the quantum level interactions that exist at nanoscale. These materials also offer enormous surface to volume ratios that would be invaluable in heterogeneous catalysis. Recent studies point at titanium dioxide nanomaterials as having strong potential to be applied in heterogeneous photocatalysis for environmental remediation and pollution control. This work reports the use of surface modified anatase TiO2 nanofibers with rhodium (Rh) nanoparticles in the photodegradation of rhodamine B (RH-B), an organic pollutant. The dimensions of TiO2 nanofibers were 150±50 nm in diameter and the size of the Rh nanoparticles was ~5 nm. The Rhdoped TiO2 catalyst exhibited an enhanced photocatalytic activity in photodegradation of rhodamine B under visible light irradiation, with 95 % degradation within 180 minutes reaction time. Undoped TiO2 did not show any notable phocatalytic activity under visible light. INTRODUCTION TiO2 nanomaterials are used as supports for heterogeneous nucleation of metal nanoparticles, with a strong potential as photocatalysts in environmental remediation. TiO2 has band gap energies of 3.0 - 3.2eV,[1] that require UV light to generate excitons involved in the photodegradation process. Efforts to shift the optical response of titania to the visible region have been actively studied for a number of years[2],[3],[4]. Doping TiO2 has been established as a way of shifting the absorption maximum band to visible range by introducing electronic states within the band gap[5]. These intermediate states trap the photogenerated electron-hole pairs while providing a lower energy path for excitation. Additionally, research has shown that a shift of titania’s absorption band to visible range can also be induced by introduction of crystal defects, which can be created through phase transformation[6] and/or variation of the crystal size of the titania[7]. The inherent differences leading to the red shift in these cases is that phase transformation and crystal size decreases/increases the band gap of titania whereas doping creates energy states within the band gap[6]. We are exploring the design, synthesis and characterization of novel TiO2 based nanomaterials for sustainable environment
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