Detailed Structural Examinations of Covalently Immobilized Gold Nanoparticles onto Hydrogen‐Terminated Silicon Surfaces

Abstract

The modification of flat semiconductor surfaces with nanoscale materials has been the subject of considerable interest. This paper provides detailed structural examinations of gold nanoparticles covalently immobilized onto hydrogen-terminated silicon surfaces by a convenient thermal hydrosilylation to form Si-C bonds. Gold nanoparticles stabilized by omega-alkene-1-thiols with different alkyl chain lengths (C3, C6, and C11), with average diameters of 2-3 nm and a narrow size distribution were used. The thermal hydrosilylation reactions of these nanoparticles with hydrogen-terminated Si(111) surfaces were carried out in toluene at various conditions under N2. The obtained modified surfaces were observed by high-resolution scanning electron microscopy (HR-SEM). The obtained images indicate considerable changes in morphology with reaction time, reaction temperature, as well as the length of the stabilizing omega-alkene-1-thiol molecules. These surfaces are stable and can be stored under ambient conditions for several weeks without measurable decomposition. It was also found that the aggregation of immobilized particles on a silicon surface occurred at high temperature (> 100 degrees C). Precise XPS measurements of modified surfaces were carried out by using a Au-S ligand-exchange technique. The spectrum clearly showed the existence of Si-C bonds. Cross-sectional HR-TEM images also directly indicate that the particles were covalently attached to the silicon surface through Si-C bonds.

Self-assembly of PEGylated gold nanorods and its optical limiting property

“…Materials and instruments: Hexadecyltrimethylammoniumbromide (CTAB) and chloroauric acid were purchased from SigmaAldrich Co., Sodium borohydride (99%) and L-ascorbic acid were purchased from Sinopharm Chemical Reagent Co., Ltd. Thiolterminated monomethyl ether of PEG (PEG-SH) was prepared from monomethyl ether of PEG (mPEG) (M n 5000) according to the thiourea route [15,16]. Deionized water was used in all the experiments.…”

Assembly and Immobilization of Metal Nanoparticles

“…Therefore, the smart design and choice of such compound is one of the research targets in this field. Indeed, many scientists have made much effort to prepare the assembly of nanoparticles with various surfactants, for example, those with different lengths of alkyl chains for hydrophobic interaction [51][52][53], those with multifunctional groups for host-guest interaction [54,55] and/or those with functional groups which can form covalent bonds [56], those with hydrogen bonding groups which can attach to DNA molecules [11,[57][58][59][60][61][62][63], bio-recognition surfactant molecules [64,65], those with charged head groups for electric static interaction with templates [60,[66][67][68], hydrosilylation between silicon and unsaturated bonds [69][70][71] and so on. In this section, we introduce the nanoparticle assemblies from the viewpoint of such unique surfactant molecules.…”

Advantages of a Programmed Surface Designed by Organic Monolayers

“…In order to fabricate such flexible device applications, it is a key to control chemical properties of polymer's surface that induce the nucleus formation of inorganic crystals, and accelerates subsequent crystalline growth or film growth. Organosilane SAMs have been frequently employed to modify surface chemically properties of inorganic substrates [1][2][3][4][5]. The resultant surfaces play important roles in molecular recognition events.…”