Structure and Photoelectrochemical Properties of Laminated Monoparticle Layers of CdS and ZnS on Gold

Monolayers of CdS and ZnS nanoparticles and their layer-by-layer composite films were fabricated on a gold substrate that was precoated with a self-assembled monolayer (SAM) of 1,6-hexanedithiol. Semiconductor nanoparticles (∼4 nm in diameter) were prepared in reversed micelles. Evidence for the attachment of nanoparticles on SAM was obtained by X-ray photoelectron spectroscopy. A photoinduced anodic current was observed when the semiconductor nanoparticle electrodes were immersed in an electrolyte solution containing triethanolamine as the electron donor. The photocurrent action spectra of nanoparticle monolayers were in good agreement with the absorption spectra of nanoparticle dispersions before immobilization, indicating that the nanoparticles were immobilized on the substrate without changing their particle size. Layer-by-layer composite films of CdS and ZnS showed photoresponse depending on the order of accumulation. This indicates the successful fabrication of a layer-by-layer structure that affects the electron transfer through nanoparticles and the penetration of the electrolyte solution.