AVS 52nd International Symposium
    Applied Surface Science Thursday Sessions
       Session AS+TF-ThM

Paper AS+TF-ThM9
Optimization and Deposition of CdS Thin Films As Applicable to TiO@sub2@/CdS Composite Catalysis

Thursday, November 3, 2005, 11:00 am, Room 206

Session: Thin Film Characterization
Presenter: K. Prabakar, Toyama University, Japan
Authors: K. Prabakar, Toyama University, Japan
T. Takahashi, Toyama University, Japan
T. Nakashima, Kashiwa Chuo High School, Japan
Y. Kubota, Yokohama City University, Japan
A. Fujishima, Kanagawa Academy of Science and Technology, Japan
Correspondent: Click to Email
Recently, the study of interparticle electron transfer between dissimilar semiconductors has received interesting investigations. Combining two semiconductor particles offers an opportunity to sensitize a semiconductor material having a large bandgap and energetically low-lying conduction band by another one having a small band gap and energetically high-lying conduction band. In our investigations, photosensitization of TiO@sub2@ by narrow band gap semiconductor such as CdS have been investigated and found to be effective for separation and transfer of photoexcited charge carriers. The TiO@sub2@ thin films were deposited by direct current reactive magnetron sputtering and CdS by chemical bath deposition. Thin films of CdS were deposited from a solution of analytical grade CdSO@sub4@ (1 M) and thiourea (1 M) in an alkaline solution of ammonia with a total volume of 80 ml. The temperature and time of the deposition were varied between 65 to 80 ° C and 30 to 60 minutes respectively. To vary the composition of the films, different concentrations of CdSO@sub4@ and thiourea were used. The optical band gap energy varied from 2.41 to 2.59 eV as the CdSO@sub4@ solution concentration increased from 0.4 to 2.8 ml while keeping the thiorea as 1.6 ml. The as deposited films were annealed at different temperatures to study the effect of structural (XRD) and surface properties (SEM and AFM) on the efficiency of the TiO@sub2@/CdS catalysis. The TiO@sub2@ films were found to be polycrystalline anatase structure with optical band gap energy of 3.1 eV. The degradation efficiency under visible light of methanol and methylene blue by TiO@sub2@/CdS films were investigated by FTIR and spectrophotometer respectively and the results are discussed in details. The visible light photocatalytic degradation efficiency TiO@sub2@/CdS is far higher than that of TiO@sub2@ film.