Photocatalytic decomposition of Methylene Blue with nitrogen-doped TiO2 under visible light irradiation



Sustain. Environ. Res., 23(1), 15-21 (2013)



Young Ku, Wan-Jiun Chen and Wei-Ming Hou


Photocatalysis, TiO2, LED, nitrogen-doped, visible light


Nitrogen-doped (N-doped) TiO2 photocatalysts were prepared by chemical vapor deposition method  under ammonia atmosphere. The photocatalytic activity of N-doped TiO2 was estimated by decomposing Methylene Blue in aqueous solution with various operating conditions, including solution pH and light source. The morphology, crystal structure, chemical composition and optical characterization of prepared N-doped TiO2 were determined by the field-emission scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, Brunauer-Emmett-Teller approach, UV-Vis diffuse reflectance spectroscopy and zeta meter. The absorption of N-doped TiO2 powder was extended into visible light regimes with an optical band gap of around 2.89 eV, which enhanced the photocatalytic activity of N-doped TiO2 samples under visible-light illumination. Photocatalytic decomposition of Methylene Blue was increased with increasing solution pH. In alkaline solution, negatively-charged N-doped TiO2 surface enhanced the Methylene Blue decomposition. Methylene Blue decomposition by photocatalytic process was increased by 67 and 30% for experiments conducted with irradiation of blue (463 nm) and green (523 nm) light.


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