Synthesis and application of N-doped TiO2/CdS/poly(1,8-diaminocarbazole) composite for photocatalytic degradation of 4-chlorophenol under visible light

Visible-driven photocatalyst was prepared by deposition of CdS by SILAR (successive ion layer adsorption and reaction) method on mesoporous N-doped TiO2 supported on F-doped tin oxide (FTO) glass substrate. The changes of morphology and optical properties of the samples with increasing amount of CdS were monitored. The edges of conduction bands of both semiconductors were determined from Mott-Schottky plots. The system with CdS deposited in 6 SILAR cycles has been tested in photocatalytic decomposition of 4-chlorophenol. The mechanism of photocatalytic reaction was discussed in terms of the role of hydroxyl radicals and superoxide radicals in the process. A thin film of conducting polymer, poly(1,8-diaminocarbazole) deposited on the surface of TiO2/CdS suppressed photocorrosion of CdS during photocatalytic process. The amount of the polymer was optimized taking into account concentration of Cd2+ ions released to the solution and activity of the system in 4-CP degradation.