%0 Journal Article
%T The Effect of Hydrothermal Treatment on Silver Nanoparticles Stabilized by Chitosan and Its Possible Application to Produce Mesoporous Silver Powder
%A Dang Viet Quang
%A Nguyen Hoai Chau
%J Journal of Powder Technology
%D 2013
%I Hindawi Publishing Corporation
%R 10.1155/2013/281639
%X Aggregation state of silver nanoparticles dispersed in an aqueous solution greatly varies with storage and treatment conditions. In this study, silver nanoparticles synthesized in chitosan solution by a chemical reduction method were hydrothermally treated at different temperatures. The variation in the aggregation state of silver nanoparticles in the solution was observed by UV-Vis spectroscopy and field emission transmission electron microscopy. Results indicated that a phase transition occurred while silver nanoparticles were hydrothermally treated for 5 h at 100 and ; however, they aggregated and completely precipitated at . Mesoporous silver powder obtained by hydrothermal treatment at was characterized by using X-ray diffraction technique, BET analyzer, and scanning electron spectroscope. 1. Introduction Silver nanoparticles have become the most widely commercialized nanomaterials due to thier unique physicochemical and biological properties [1]. Silver nanoparticles can be synthesized and stabilized in the presence of polymers [2¨C7] in an aqueous solution or organic solvents. They can also be stabilized in the pores of porous materials where tiny spaces or channels act as spatial hindrance, which inhibits the growth of silver particles [8¨C11]. The size and shape of silver nanoparticles in porous materials depend on their pore diameters and are almost stable after synthesis, whereas that of silver nanoparticles in solutions is affected by various factors including storing conditions, the type and concentration of stabilizer, the concentration of silver nanoparticles, and synthetic routes. The properties, applicability and efficiency of final products are greatly related to the size, the shape, and the aggregation state of silver nanoparticles. Silver powder has been widely used in catalysis, electronics, chemical industry, and biomedical application [12]. Electronic industry consumes large amounts of silver powder that is usually used as conductive paste [13¨C16]. Several studies have indicated that mesoporous silver powders with higher porosity and larger surface area engender higher application efficiencies such as reducing firing temperature of conductive film [17], enhancing the resistance of heat exchanger material at ultralow temperature [18], or increasing catalytic activity of an oxidation reaction [19, 20]. Recently, due to the rapid development of electronic industry, it demands a huge amount of high quality silver powder. Thus, scientists have investigated and proposed different methods such as spray pyrolysis [21¨C23], sonochemical
%U http://www.hindawi.com/journals/jpt/2013/281639/