Optical properties and photocatalytic activity of CdS-TiO2/graphite composite

TiO film was applied to graphite substrate through chemical bath deposition (CBD) method with TiCl as precursor. CdS was deposited on TiO /graphite (TiO2/G) by CBD with precursors of CdSO . A UV-Vis diffuse reflectance (UV-Vis DR) analysis was used to analyze the optical properties and band gap energy. Meanwhile, photocatalytic activity was determined from the quantum yield (QY) value of isopropanol degradation. The X-ray diffraction pattern shows that the TiO film contains rutile and anatase phases. UV-Vis DR spectrum shows the photoactivity in the visible light area and provides lower band gap value due to CdS deposition. TiO /G provide energy gap at 3.0 eV, which indicates that rutile phase is dominant. Meanwhile, CdS-TiO /G shows multiple energy gaps representing CdS at 2.4 eV, rutile at 3.0 eV, and anatase at 3.2 eV. The QY values of CdS-TiO /G are 7.98×10 and 8.62×10 at 450 and 380 nm of radiation light, respectively. These values are higher than the QY of TiO /G and TiO -P25/graphite (TiO2-P25/G), which are 1.19×10 and 5.0×10 , respectively. The photocatalytic reaction follows the first-order reaction. CdS deposition allows the rate constant to increase from 2×10 to 13×10 under UV radiation.