GROWTH OF SILICALITE-1 FILMS ON GOLD SUBSTRATES

The crystallisation of thin continuous silicalite-l films on modified gold surfaces prepared at 100 degrees C in clear precursor solutions h as been studied by grazing angle X-ray diffractometry, infrared spectr oscopy, dynamic light scattering, scanning electron microscopy, Kr ads orption and ellipsometry. The gold surfaces were pre-treated with a si lane coupling agent, gamma-mercaptopropyltrimethoxysilane, and hydroly sed in an acidic solution, pH<4, to create a modified negatively charg ed interface on which positively charged colloidal silicalite-l seed c rystals were adsorbed. The colloidal seed crystals are believed to be preferentially adsorbed with their (010) face parallel to the Au surfa ce. Continued growth of the oriented seed crystals in a following hydr othermal step results in the formation of a continuous thin oriented c rystalline film. The mechanism for the formation of silicalite-l films on Au is discussed. (C) 1997 Elsevier Science B.V.