Preparation, characterization and application of CuCrO2/ZnO photocatalysts for the reduction of Cr(VI)

The delafossite CuCrO2 elaborated by sol-gel from 40 nm diameter colloid is optically active in the visible region. It is characterized physically and photoelectrochemically. The microstructure is fairly homogenous with a mean crystallite size of ca. 2 μm. The optical gap (1.30 eV), determined from...

Full description

Saved in:
Bibliographic Details
Published in:Journal of environmental sciences (China) 2012-12, Vol.24 (12), p.2173-2179
Main Authors: Ketir, Wahiba, Rekhila, Gharib, Trari, Mohamed, Amrane, Abdelatif
Format: Article
Language:English
Subjects:
adsorption
Catalysis
chromate
chromium
Chromium - chemistry
Chromium - radiation effects
Copper - chemistry
Copper - radiation effects
crystallites
CuCrO2
delafossite
electrons
exhibitions
hydrogen
hydrogen production
lighting
microstructure
Minerals - chemistry
Oxidation-Reduction
photocatalyst
photoreduction
reflectance
salicylic acid
solar radiation
zinc oxide
Zinc Oxide - chemistry
ZnO
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:The delafossite CuCrO2 elaborated by sol-gel from 40 nm diameter colloid is optically active in the visible region. It is characterized physically and photoelectrochemically. The microstructure is fairly homogenous with a mean crystallite size of ca. 2 μm. The optical gap (1.30 eV), determined from the diffuse reflectance, is well suited to the sunlight spectrum. The Mott Schottky plot is characteristic of P-type conductivity with a flat band potential of −0.26 VSCE. As application, the photoreduction of chromate is successfully achieved in air-equilibrated suspension CuCrO2/ZnO (1/1). CuCrO2 is photoactivated by visible light and the electrons in the conduction band (−1.34 VSCE) are injected to ZnO. In the presence of salicylic acid, a conversion of Cr(VI) to Cr(III) of 57% is obtained under optimal conditions (pH 3 at 25°C, 5 × 10−4 mol/L) because of the HCrO4− dark adsorption onto ZnO (4HCrO4− + 3C7H6O3 + 18O2 + 16H+ → 4Cr3+ + 21CO2 + 19H2O, ΔG0 = −557 kcal/mol). Prolonged illumination is accompanied by a deceleration in the photoactivity owing to the competitive water reduction, an issue of energetic concern. The hetero-system exhibits self sensitization for hydrogen production with an evolution rate of 149 μmol/(hr·g).
ISSN:1001-0742
1878-7320
DOI:10.1016/S1001-0742(11)61043-7