Photocatalytic degradation of photosensitizing and non-photosensitizing dyes over chromium doped titania photocatalysts under visible light

• Published in: Journal of photochemistry and photobiology. A, Chemistry. Chemistry., 2017-01, Vol.332, p.215-223
• Main Authors: Koh, Pei Wen, Hatta, Mohd Hayrie Mohd, Ong, Siew Teng, Yuliati, Leny, Lee, Siew Ling
• Format: Article
• Language: English
• Subjects: Anatase; Catalytic activity; Chromium; Chromium doping; Congo red; Degradation; Dopants; Dyes; Fluorescence; Irradiation; Light irradiation; Methylene blue; Phase transitions; Photocatalysis; Photocatalyst; Photocatalysts; Photodegradation; Photosensitization; Radiation; Recombination; Titania; Titanium dioxide
• ISSN: 1010-6030; 1873-2666
• DOI: 10.1016/j.jphotochem.2016.08.027

[Display omitted] •Cr doped TiO2 photocatalysts were tested over photocatalytic degradation of photosensitizing and non-photosensitizing dyes under visible light irradiation.•The nature of targeted subtract in photocatalysis reaction affects greatly the photocatalytic performance of the photocatalysts.•Possible mechanisms for photocatalytic degradation of the two different dyes over the photocatalysts are proposed. A series of 0.5–4mol% Cr-doped TiO2 photocatalysts were tested over photocatalytic degradation of photosensitizing (Methylene Blue) and non-photosensitizing (Congo Red) dyes under visible light irradiation. Presence of Cr dopant has induced anatase-rutile phase transition, leading to high rutile percentage of 45% in the material. Besides, the addition of Cr dopant has extended the absorption wavelength of TiO2 to visible light region. As evidenced from the fluorescence analysis, electron-hole recombination rate of Cr-doped TiO2 decreased with increasing of Cr dopant content up to 3mol% in the materials. Despite using the same series of photocatalysts, the optimum amount of Cr dopant which gave the best photocatalytic activity was different: 1mol% Cr-doped TiO2 and 3mol% Cr-doped TiO2 were the best photocatalysts for photodegrading Methylene Blue and Congo Red, respectively. The results strongly suggested that the nature of targeted subtract in photocatalysis reaction affected the photocatalytic performance of the Cr-doped TiO2. Possible mechanisms for photocatalytic degradation of the two different dyes over the photocatalyst were presented.