Visible Light Induced NO sub(2) super(-) Removal Over CuCrO sub(2) Catalyst

• Published in: Water, air, and soil pollution air, and soil pollution, 2009-05, Vol.199 (1-4), p.115-122
• Main Authors: Ketir, Wahiba, Bouguelia, Aissa, Trari, Mohamed
• Format: Article
• Language: English
• ISSN: 0049-6979; 1573-2932
• DOI: 10.1007/s11270-008-9864-z

The delafossite CuCrO sub(2) is a promising candidate for the visible light driven catalysis. The NO sub(2) super(-) removal by photoelectrochemical process is studied under mild conditions, close to that encountered in the natural environment. CuCrO sub(2) exhibits a long term chemical stability with a corrosion rate of 0.34kmol m super(-2) year super(-1) in KCl (0.5M). A forbidden band of 1.3eV has been evaluated from the diffuse reflectance spectrum. The flat band potential (-0.07 V sub(SCE)) determined from the Mott-Schottky plot is close to the photocurrent onset potential (0 V sub(SCE)). Hence, the conduction band is positioned at -1.08 V sub(SCE) and thus lies below the NO sub(2) super(-) level leading to a feasible reduction upon visible illumination. The conversion occurs in less than 5h with a quantum efficiency of 0.5%. The possibility of identifying the reaction products via the intensity-potential characteristics was explored by using standard solutions. The decrease of the conversion rate over time is attributed to the competitive water reduction. In absence of catalyst, NO sub(2) super(-) is oxidized to NO sub(3) super(-) in air equilibrated solution and the reaction follows a first order kinetic with a half life of 21h, NO sub(3) super(-) has been identified by iodometry through copper titration.