Doping of TiO 2 nanopowders with vanadium for the reduction of its band gap reaching the visible light spectrum region
- PDF / 343,993 Bytes
- 4 Pages / 612 x 792 pts (letter) Page_size
- 53 Downloads / 167 Views
esearch Letters
Doping of TiO2 nanopowders with vanadium for the reduction of its band gap reaching the visible light spectrum region Majid Ahmadi, Department of Physics, College of Natural Sciences, University of Puerto Rico, PO Box 70377, San Juan, Puerto Rico 00936-8377 Maxime J-F. Guinel, Department of Physics, College of Natural Sciences, University of Puerto Rico, PO Box 70377, San Juan, Puerto Rico 00936-8377; Department of Chemistry, College of Natural Sciences, University of Puerto Rico, PO Box 70377, San Juan, Puerto Rico 00936-8377 Address all correspondence to Maxime J-F. Guinel at [email protected] (Received 6 March 2014; accepted 13 May 2014)
Abstract Titanium oxide (TiO2) nanoparticles (NPs) were doped with vanadium using a novel, facile, and inexpensive method. The TiO2 NPs were dispersed in a vanadyl oxalate solution prepared by dissolving vanadium pentoxide (V2O5) in oxalic acid. A short heat treatment at 400 °C applied to the dried mixture resulted in the doping of TiO2 with a net measured decrease of its band gap by about 0.5 eV, making this important semiconductor material usable in the visible light spectrum.
Introduction Titanium oxide (TiO2) is a widely used semiconductor presenting some advantages because of its optical and electrical properties, non-toxicity, chemical stability, and low production cost. Fujishima and Honda[1] proposed its usage as a photocatalyst using ultraviolet (UV) irradiation but its application has been limited due to its wide band gap (Eg: 3.0–3.2 eV). Moreover, TiO2 has a very low photo-quantum yield due to the easy recombination of excited electrons. However, it is possible to decrease the value of its Eg and increase its photo-quantum yield by doping it with appropriate elements. The doping of TiO2 with vanadium (V) increases its photocatalytic efficiency and makes it more active in the visible light spectrum.[2,3] Different methods have already been used to synthesize V-doped TiO2 catalysts: immersion in an NH4VO3 solution,[4] sol–gel[2,5], and controlled hydrolysis of tetrabutyl titanate in a V ion solution.[6] These techniques are all relatively complex and not appropriate for industrial applications. In this paper, we report on a novel and much simpler method to synthesize V-doped TiO2 nanoparticles (NPs) for its usage as a visible light-driven semiconductor. In a first step, a vanadyl oxalate solution (VOC2O4) was prepared from oxalic acid (H2C2O4) and vanadium pentoxide (V2O5). In a second step, the products were annealed at 400 °C in ambient air. The Eg for TiO2 was red-shifted by about 0.5 eV, which is encouraging.
Materials and methods Commercial V2O5 microparticles were dissolved in H2C2O4 to produce a 0.10 M VOC2O4 solution. All chemicals were
purchased from Sigma-Aldrich Company. This solution was kept at a temperature of 50 °C and stirred for 24 h. A clear blue VOC2O4 solution (the color is due to the presence of V4+ ions) was obtained according to the reaction V2 O5 + 3 H2 C2 O4 2 VOC2 O4 + 2 CO2 + 3 H2 O 0.080 g (0.001 mole) of TiO2 NPs (pur
Data Loading...
