Synthesis of Mesoporous Silica Nanocomposites for Preparation of Gold Nanoparticles

Abstract

Gold nanoparticles (AuNPs) having particle size less than 10 nm can exhibit enhancement of surface area to give high activity such as in catalytic reaction. However, it is hard to synthesize AuNPs with small particle size due to the strong agglomeration. Herein we report that channels of mesoporous silica synthesized via the template sol-gel synthesis can be used to prepare AuNPs by calcination method. Mesoporous silica with an interpore distance of 4.1 nm was successfully fabricated as transparent thin film by using an amphiphilic trinuclear gold (I) pyrazolate complex as a template for the sol-gel synthesis. Upon calcination at 450 °C for 3 h, silica film nanocomposites showed red-shifting of surface plasmon resonance (SPR) bands from 518 (AuNPs from the bulk) to 544 nm owing to decreasing of the average particle size. The formation of AuNPs was also supported by the appearance of diffraction peaks of d111 at 2θ = 38.20° having a cubic phase. Moreover, transmission electron microscope (TEM) images and X-ray diffraction (XRD) peaks also showed smaller and more homogenous distribution of AuNPs.

Supramolecular Phosphorescent Trinuclear Copper(I) Pyrazolate Complexes for Vapochromic Chemosensors of Ethanol

“…4a). Such luminescent profile gave a large Stokes shift (∆λ) in 279, 304, 290, 322 and 338 nm, indicating the characteristics of phosphorescent compounds [21,[23][24][25][26][27][28][29][30][31][32][33][34]. Moreover, the luminescent decay measurements in excitation and emission maxima as shown in Fig.…”

Highly ordered mesoporous silica film nanocomposites containing gold nanoparticles for the catalytic reduction of 4-nitrophenol

“…In our previous reports [31–32], we highlighted the morphology of mesoporous silica composites after both types of heat treatments at 450 and 250 °C by calcination for 3 hours and thermal hydrogen reduction for 2 hours. In this current work, we have only selected the best two samples from each heat treatment process (calcination at 250 °C and thermal hydrogen reduction at 210 °C) for the TEM measurements.…”

“…Surface plasmon resonance (SPR) peaks in the UV–vis spectrum in the range of 500 to 600 nm can be used to identify the presence of AuNPs [40]. Before calcination or thermal hydrogen reduction was conducted, [Au 3 Pz 3 ] C10TEG and [Au 3 Pz 3 ] C10TEG /silica hex showed absorption bands for π–π stacking of the benzene rings at less than 350 nm without SPR peaks at 500–600 nm [31–32]. After both heat treatments, Fig.…”

“…Recently, mesoporous silica nanomaterials were not only used as a support to control the size of the AuNPs [28], but also to enhance the thermal stability after heat treatment at high temperature [29]. In our previous works, high purity [Au 3 Pz 3 ] C10TEG [30] was used to fabricate [Au 3 Pz 3 ] C10TEG /silica hex for synthesizing AuNPs in the nanocomposites via calcination ([AuNPs] cal /silica hex ) [31] and thermal hydrogen reduction methods ([AuNPs] red /silica hex ) [32]. However, the resulting quality of the mesoporous silica nanomaterials was quite low based on their characteristic diffraction peaks and microscopy images.…”

Designed Mesoporous Materials toward Multifunctional Organic Silica Nanocomposites

“…The formation of AuNPs were confirmed by using TEM with the appearance of spherical particles, XRD with the presence of a diffraction peak at 38.2° and UV-Vis spectrometer with the presence of surface plasmon resonance (SPR) peak at 544 nm [56]. Moreover, by using thermal hydrogen treatment at 250°C for hours, it provided the purplish-pink thin film with SPR peak at 558 nm due to the decreasing of particle size [57]. On the other hands, the main diffraction peak at the small-angle area for indicating the hexagonal structure were shifted to higher angle due to the formation of more higher order structure with the same geometry and increasing in pore size.…”