Coating nonfunctionalized silica spheres with a high density of discrete silver nanoparticles

Abstract

Reducing AgNO 3 by glucose at basic pH coated the surface of silica spheres with a high density of hemispherical silver nanoparticles (average diameter 3.2±1 nm). A much lower silver concentration than is standard favored heterogeneous nucleation of silver on the silica surface at the expense of homogeneous nucleation in solution. The slow growth rate of the nuclei promoted the formation of discrete silver particles rather than a continuous shell. Based on scanning electron microscopy and transmission electron microscopy, the surface coverage of silver seed particles was as high as 25% at 10• C without prior functionalization of the silica. The particles were composed of metallic silver based on x-ray photoelectron spectroscopy. There was a sharp increase in the silver surface coverage and decrease in the particle size when the temperature was raised from 5 • C to 10 • C and the amount of silica was decreased from 0.2 to 0.025 V/V%. The size was controlled by the diffusion barrier through the ion shell surrounding the silica spheres and by maintaining reaction conditions where the particles on the surface compete for silver.

Silver Nanoshells with Optimized Infrared Optical Response: Synthesis for Thin-Shell Formation, and Optical/Thermal Properties after Embedding in Polymeric Films

“…Several routes were developed to obtain a high silver particle density on silica particles. These include using glucose to reduce silver at high pH values [ 35 ], or directly onto the thiol-functionalized particles [ 36 ], sonochemical deposition [ 37 ], and pretreatment steps in electroless plating [ 38 ]. The latter method uses the reduction of ammoniacal silver onto Sn 2+ -sensitized particles and was used to synthesize Ag nanoshells [ 9 , 39 , 40 ].…”

Facile Histamine Detection by Surface-Enhanced Raman Scattering Using SiO2@Au@Ag Alloy Nanoparticles

“…Compared with other standard methods, such as HPLC, these SERS methods have the advantages of sensitivity, reliability, and easy fabrication; however, precise control of the size and amount of the aggregated particle clusters is difficult because of the heterogeneous formation of the metal particles. The use of a template, such as silica particles or polymer beads, to accumulate silver or gold nanoparticles (NPs) has been widely established in order to control particle size [20][21][22][23][24][25][26][27][28]. Recently, our group produced an Au-Ag alloy on silica nanoparticles as a highly sensitive and reliable SERS probe that can detect molecular targets at very low concentrations [29][30][31][32][33][34][35][36][37][38][39][40][41][42].…”

Improvements on electrical conductivity of the electrospun microfibers using the silver nanoparticles

“…In this study, PES microfibers were prepared via electrospinning and employed as the matrix material to adsorb dopamine and synthesize PDA in situ . After polymerization, a solution of silver nitrate (AgNO 3 ) was incorporated into the PES microfibers and reduced to Ag NPs using glucose acetic acid solution . The electrical conductivity and morphology of the resulting PES/PDA/Ag NPs microfibers were systematic evaluated under the different conditions.…”