Fabrication of a TiO2-BDD heterojunction and its application as a photocatalyst for the simultaneous oxidation of an azo dye and reduction of Cr(VI).
A TiO2-boron doped diamond (TiO2-BDD) heterojunction was employed as a photocatalyst to simultaneously oxidize an azo dye C.I. reactive yellow 15 (RY15) and reduce hexavalent chromium (Cr(VI)). This heterojunction was fabricated first by depositing a BDD film on a Ti sheet in a hot filament chemical vapor deposition reactor, followed by covering a layer of TiO2 in a metal-organic chemical vapor deposition system. The morphology of this heterojunction was characterized by using a scanning electron microscope (SEM). X-ray diffraction (XRD), Raman spectroscopy, and current-voltage (I-V) measurement were used to characterize its structures. Additionally, the characterization of surface photovoltage showed that the TiO2-BDD heterojunction exhibited a higher photovoltage response and a better ability for charge separation than the photocatalyst of TiO2 directly deposited on a Ti sheet (TiO2-Ti). The photocatalytic experiments revealed that the kinetic constants for the oxidation of RY15 and the reduction of Cr(VI) were, respectively, increased by 85 and 71% when the photocatalyst of TiO2-Ti was replaced by the TiO2-BDD heterojunction. Meanwhile, a significant synergy was confirmed in the simultaneous oxidation of RY15 and reduction of Cr(VI). The enhanced photocatalytic ability of the TiO2-BDD composite could be attributed to the heterojunction. The possible photocatalytic mechanism was also discussed.
Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education, China), School of Environmental and Biological Science and Technology, Dalian University of Technology, Dalian 116024, China.
Hongbin
H
Yu
Shuo
S
Chen
Xie
X
Quan
Huimin
H
Zhao
Yaobin
Y
Zhang
D001391:Azo Compounds / Q000737:chemistry*; D002384:Catalysis; D002857:Chromium / Q000737:chemistry*; D004396:Coloring Agents / Q000737:chemistry*; D008855:Microscopy, Electron, Scanning; D010084:Oxidation-Reduction; D010777:Photochemistry; D014025:Titanium / Q000737:chemistry*
D001391:Azo Compounds; D004396:Coloring Agents; D002857:Chromium; C009495:titanium dioxide; D014025:Titanium