Dithiol-mediated incorporation of CdS nanoparticles from reverse micellar system into Zn-doped SBA-15 mesoporous silica and their photocatalytic properties

CdS nanoparticles, as prepared in reverse micellar systems, were incorporated into alkanedithiol-modified Zn-doped SBA-15 mesoporous silica (dtz.sbnd;ZnSBA-15; pore diameter, ca. 4 nm), which were themselves prepared via hydrolysis of tetraethylorthosilicate (TEOS) in the presence of Zn(NO(3))(2) and triblock copolymer, as a nonsurfactant template and pore-forming agent, followed by contact with dithiol molecules. A particle-sieving effect for the dtz.sbnd;ZnSBA-15 was observed, in that the incorporation of the nanoparticles was remarkably decreased with increasing the nanoparticle size. The resulting CdSz.sbnd;ZnSBA-15 composite was then used as photocatalysts for the generation of H(2) from 2-propanol aqueous solution. Under UV irradiation (lambda>300 nm), a high photocatalytic activity was observed for this composite material. This is effected by electron transfer from the photoexcited ZnS (dithiol-bonded Zn on SBA-15) to CdS nanoparticles. The photocatalytic activity is increased with a decrease in the number of methylene groups in the dithiol molecules, according to the rank order 1,10-decanedithiol < 1,6-hexanedithiol < 1,2-ethanedithiol.