ChemInform Abstract: Photochemistry of Semiconductor Colloids. Part 22. Electron Injection from Illuminated CdS into Attached TiO2 and ZnO Particles.

ChemInform Abstract

Colloidal solutions of CdS containing colloidal TiO₂ or ZnO are illuminated with visible light. TiO₂ is observed to quench the fluorescence of CdS and to enhance drastically the photoanodic corrosion in aerated solutions. In deaerated CdS solutions containing MeOH and excess Cd²⁺ ions, metallic Cd is formed in the presence of TiO₂. The reduction of methyl viologen is ten times faster in the presence of TiO₂ than without TiO₂ (quantum yield of close to 1 in the presence of TiO₂). These effects are explained in terms of improved charge separation by rapid electron injection from illuminated CdS into the conduction band of TiO₂. Electron injection into ZnO is less efficient and occurs only in the case of Q-CdS particles (very small particles with a greater band gap).