Preparation And Analysis Of Functional SiO₂/Au Nanomaterials

Biomimetic synthesis of inorganic nanomaterials has attracted great attention due to their delicate structures and excellent properties of the biomaterials and mild forming conditions.Noble metal nanoparticles including Au and Pt have unique optical,electrical,catalytic and biological affinity properties.Loading noble metal on inorganic nanomaterials may obtain new collaborative features and result in wider application.In this paper,we firstly synthesized 1D SiO₂ nanomaterials with surficial sulfhydryl groups by imitating the biosilica formation,and then prepared 1D SiO₂/Au nanomaterials by loading gold nanoparticles with different size on silica surface.The 1D SiO₂/Au nanomaterials may exhibit unusual properties and get new application due to their special hybrid structure.Ultra-short peptide I₄K₂ assemblies were adopted as templates and（TEOS）and（MPTES）as silicon precursors,and 1D silica nanomaterials with surficial sulfhydryl groups were prepared at a mild condition.Here,amino groups on the surface of the I₄K₂ nanofibers served as catalytic sites for both hydrolysis and condensation of silica precursors（TEOS and MPTES）,and the peptide assemblies worked as templates for directing silica deposition.Besides,considering that the negatively charged organic molecules are necessary during the biosilica formation,we designed anionic amphiphilic ultrashort peptide I₃E which can assemble into nanofibers in aqueous solution,and synthesized silica nanostructures with controllable sizes.Interestingly,silica nanotubes with amino modified on the inner surface can be obtained by removing the peptide templates.We then prepared gold nanoclusters（AuNCs）of 1-3 nm and loaded them on the silica nanomaterials with surficial sulfhydryl groups and therefore constructed SiO₂/Au nanomaterials.The SiO₂/Au nanomaterials can be used to detect Hg²⁺and exhibit high sensitivity and selectivity.More interestingly,the functional SiO₂/Au nanomaterials can be used repeatedly which is rarely reported previously.In addition,we prepared gold nanoparticles（AuNPs）of 5-7 nm and loaded them on silica nanomaterials with surficial sulfhydryl groups.The catalytic performances of prepared functional nanomaterials were evaluated by a model reaction of catalytic reduction of 4-nitrophenol to 4-aminophenol.It was found that the prepared functional nanomaterials exhibited well catalytic activities(the apparent rate constant is 0.155 min^-1).Furthermore,such functional materials can be separated from the reaction system through a facile centrifugation at the end of reaction or any stage of the reaction.The results indicated that the functional materials had desirable characteristics because of their good catalytic activities and easily removable properties.