Controlling the Formation of Silver Nanoparticles on Silica by Photochemical Deposition and Other Means^†

Abstract

Silver nanoparticles (Ag-NP) on silica were produced in aqueous solution by deposition of silver on colloidal silica in a small cuvette using radiation from a xenon-mercury lamp. Ag-NP were also synthesized on a much larger scale with low-level, long-term visible light irradiation for several months. In both cases, the nanoparticle production was monitored by the appearance of the surface plasmon resonance (SPR) band at around 410 nm. The growth of the nanoparticles was directly related to the time exposed to radiation, which could be tracked spectrophotometrically over time. We also investigated the possibilities of rapid nanoparticle production without the assistance of radiation though silver oxide by adding alkali hydroxide, which is a relatively unexplored approach for syntheses of Ag-NP on silica. The SPR absorption of Ag-NP was used as a tool in evaluating the size and shape of the resulting nanoparticles along with dynamic light scattering and transmission electron microscopy data. In order to better utilize and understand Ag-NP, we present various ways to control their production through initial concentration adjustments, irradiation effects, gravitational fractionation, sonication and silver oxide formation.

Facile and green synthesis of silver nanoparticles in quaternized carboxymethyl chitosan solution

“…It is noteworthy that we could obtain Ag NPs in several minutes via the environmentally friendly method. In addition, with longer time and higher temperature, the SPR (surface plasmon resonance) becomes stronger, indicating that the content of Ag NPs becomes higher [32,33]. Furthermore, the prepared colloid containing Ag NPs shown in figure 2 was light yellow and transparent, showing that the Ag NPs were well dispersed without aggregation [17].…”

Source and Pathway of Silver Nanoparticles to the Environment

“…The reduction of Ag + to AgNPs by Fe 2+ was later suggested as a green method to prepare AgNP-loaded nanohybrids [35]. The reduction of Ag + to Ag 0 or AgNPs was also observed on surface of granular activated carbon [36], bentonite [37,38], and silica [39,40]. For example, by mixing 25 mL of 30 mmol L −1 AgClO 4 with 10 g Ca-montmorillonite, Ag + could be adsorbed in the interlayer space and on the edges of bentonite by cation exchanged, leading to the uniform distribution of Ag + on atomic scale.…”

“…Scanning electron microscopy (SEM) test revealed that further incubation of the mixture induced the reduction of Ag + to Ag 0 in nano-or micro size [38]. Under light irradiation (Xe-Hg lamp or visible light), reduction of Ag + to AgNPs on colloidal silica was observed and monitored by the appearance of the SPR band at around 410 nm [40]. TEM showed that the size of formed AgNPs were in the range of 10-40 nm.…”