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.
Yu
Hongbin
H
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.
Chen
Shuo
S
Quan
Xie
X
Zhao
Huimin
H
Zhang
Yaobin
Y
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