Electrodeposition of Cadmium Selenide/Poly-o-Anisidine Composite

Cadmium selenide is under interest due to its optical properties: direct bandgap of the width 1.7 eV and higher abrosption coefficient comparatively to indirect semicoductors. These properties make CdSe a promising candidate for wide range of applications: fotovoltaics, hydrogen photogeneration, and electronics. Photocorrosion is the major problem in the application of CdSe in photogalvanic cells as a photoelectrode. To prevent it, we have been electrosynthesized composite CdSe/poly o-anisidine (POMA).

CdSe/POMA composite was obtained via electrodepostion on HOPG surface. The electrodeposition potentials of CdSe and POMA differs, but it will be shown that there are conditions under which it is possible to deposit one compound over another without decomposition of first one especially CdSe which is easy to oxidize in relatively high anodic potentials where o-anisidine starts to polymerize. The deposits were prepared by a cyclic potentiodynamic technique. Cadmium selenide was deposited from a bath containing 5 mM Cd²⁺ and 1mM SeO₂. POMA was deposited from 0.06 M o-anisidine solution.

The Raman and XPS spectroscopies were applied for the chemical composition of synthesized composite films determination. Photoactivity of the samples was monitored by cyclic voltammetry and potentiostatic techniques in 0.1M HClO₄. The formation of composite greatly enhances time stability of the CdSe photoelectrode. Additionally, the formation of p/n junction between CdSe and POMA enhance photoresponse of the studied system. The width of band gap for each compound was determined by reflective UV-Vis spectroscopy and STS techniques. Atomic Force Microscopy was used to show morphology of each sample and to determine thickness of each deposited layer by nanoscrathing technique.