Preparation and Properties of Silver Sols by Reduction of Silver Halides with Formaldehyde

Abstract

An analysis of some Bredig silver sols showed them to be unsuitable for some investigations recently begun. The precipitated colloid was found to contain from 26 to 44% of silver oxide depending, among other things, on the amount and kind of electrolyte used for stabilizing. Approximately a liter of the gases given off during the preparation of Bredig silver sols was collected and analyzed. The gases consisted of 22.1% oxygen and 77.9% hydrogen by volume. There was, therefore, an equivalent of 11.2% oxygen united with the silver to form silver oxide.A silver colloid comparable in constitution and properties to Zsigmondy gold sols seemed desirable, so a method of reduction with formaldehyde without the use of a protective colloid was developed.

Hierarchical synthesis of silver nanoparticles and wires by copolymer templates and visible light

“…The synthesis of AgNPs generally involves the use of reducing agents [31][32][33][34][35][36] and organic stabilizers [19][20][21][22][23][24][25][26][27][28][29]. In this study, AgNO 3 was reduced in the presence of POE-functionalized SMA copolymers under exposure to visible light.…”

“…Organic surfactants such as cetyltrimethylammonium bromide (CTAB) [30] may be present to form rod-shaped micelles which consequently direct the formation of the silver morphology. Sodium borohydride [31,32], formaldehyde [33], hydrazine [34,35], ethylene glycol [27] and poly(ethylene glycol) (PEG) [36] are commonly used as reducing agents. Physical methods such as photo-reduction [37][38][39], ultraviolet light [40], microwaves [41] and the involvement of organic polymers such as PVA [40] and PEG [36] have been reported in the literatures.…”

Reactions of Chloramines with Ag(0) and Ag(I) States

“…Reaction was slow with this initiator or colloidal silver (14). However Tollens' silver (formaldehyde reduction of Tollens' solution) proved to be an effective and reproducible reagent when used in 2.5-3 M ratio.…”