Bi2S3/TiO2 and CdS/TiO2 heterojunctions as an available configuration for photocatalytic degradation of organic pollutant

Bi2S3/TiOi(2) and CdS/TiO2 heterojunctions were prepared by direct mixture of both constituents and by precipitation of the sensitizer with commercial TiO2 at different concentrations. UV-Vis spectroscopy analysis showed that the junctions-based Bi2S3 and US are able to absorb a large part of visible light (respectively up to 800 and 600 nm). This fact was confirmed by photocatalytic experiment performed under visible light. A part of charge recombination that can take place when both semiconductors are excited was observed when photocatalytic experiment was performed under UV-Vis illumination. Orange II, 4-hydroxybenzoique acid (4-HBZ) and benzamide (BZ) were used as pollutants. Photoactivity of the junctions was found to be strongly dependent on the substrate. The different phenomena taking place in each case are discussed. (C) 2004 Elsevier B.V. All rights reserved.