PREPARATION AND CHARACTERIZATION OF SELENIDE SEMICONDUCTOR PARTICLES IN SURFACTANT VESICLES

Cadmium, lead, indium, and zinc selenide particles have been in situ generated on the surfaces of negatively charged dihexadecyl phosphate (DHP) and positively charged dioctadecyldimethylammonium bromide (DODAB) vesicles. Selenide particles were formed by two different methods. In method A, MSe particles were in situ generated from M2+-coated DHP or (MH2EDTA)2-coated DODAB vesicles by exposure to gaseous H2Se. In method B, MSe particles were formed by the chemical reduction of SeO2 and M2+ in the presence of DHP vesicles. Selenide particle formation was monitored by absorption spectroscopy. Increasing the amount of H2Se added and decreasing the pH of the solution shifted the absorption edge to higher wavelengths, which indicated the formation of larger particles. On standing particles, generated by the addition of H2Se to their precursors attached to DHP vesicles, underwent time-dependent growth. Selenide particles, formed by chemical reductions, and those generated by the addition of H2Se to Cd/EDTA-coated DODAB vesicles appeared to be smaller and more stable than their counterparts in DHP vesicles. Bandgap irradiation of the surfactant-vesicle-supported selenide semiconductor particles led to charge separation and to electron transfer to methylviologen in the presence of sacrificial electron donors (glucose or cysteine). Electron transfer have been verified by photocurrent measurements and absorption spectrophotometry. © 1990 American Chemical Society.