FORMATION AND PHOTOCATALYTIC PROPERTIES OF Q-SIZED NANOPARTICLES OF VARIOUS TRANSITION-METAL SULFIDES IN THE INNER CAVITIES OF LECITHIN VESICLES MODIFIED WITH SODIUM DODECYL-SULFATE

Modification of lecithin vesicles by the incorporation of the ionogeni c surface-active compound sodium dodecylsulphate into the lipid membra ne influences the growth of ultrafine (40 Angstrom or less) semiconduc tor sulphide particles inside the cavities of the vesicles. Particles of CdS, CuSx, PbS and ZnS can be synthesized by encapsulating EDTA-met allocomplex precursors in the vesicle cavities and adding sulphide ani ons to the water phase outside the cavities. The optical spectra of Cd S aggregates synthesized by this method differ significantly from thos e of CdS inside ''unmodified'' vesicles, and possess two distinct exci ton maxima characteristic of cluster-like Q-sized sulphide nanoparticl es of approximately 10 Angstrom. The spectral shapes of these aggregat es remain unchanged during growth; the sulphide nanoparticles formed e xhibit a planar or ''crumbly'' structure, the particles being bound to both dodecylsulphate and EDTA anions. The concentration of dodecylsul phate in the membrane and the solution PH and temperature strongly aff ect the initial rate of CdS particle growth. The Q-sized CdS and CuS, particles in the inner cavities of the lipid vesicles appear to be pho tocatalytically active in a process of vectorial electron phototransfe r through the lipid-water interface to cetylviologen incorporated into the membrane.