Green Synthesis And Research Of Silver Nanocolloids

Nano-materials have drawn a lot of interest for their unique size-dependent properties. Noble metal nano-materials such as gold and silver nanocolloids are widely used in research of catalysis, medicine, surface enhanced Raman scattering (SERS). Among noble metal nano-materials, silver nanoparticles possess unique optical, electrical and catalytic properties. Recent years, the preparation technology of silver nanocolloids has witnessed a rapid development. Finding green and facile ways to synthesize silver nanocrystals has been an important trend.Silver nanoparticles with different morphologies were prepared in aqueous solutions using green chemical reagents by chemical reduction methods in this work. The synthesized silver nanocrystals were characterized by UV-visible spectroscopy, particle size distribution analysis, X-ray powder diffraction, transmission electron microscopy, high resolution transmission electron microscopy, selected area electron diffraction, scanning electron microscopy and Fourier transform infrared measurements.Firstly, Silver nanocolloids were prepared using sodium carboxymethylcellulose as protecting agent and gallic acid and pyrogallic acid as reducing agents respectively. Secondly, the influences of reaction parameters (reaction temperature, sodium carboxymethylcellulose with different molecular weight and sodium carboxymethylcellulose contents) on experiment results were discussed in detail. Results showed that, silver nanospheres with different sizes and silver nanoplates (both triangular plate and disk) were obtained in suitable situations using gallic acid as reducing agent; meanwhile, silver nanospheres with narrow size distribution could be prepared using pyrogallic acid as reductant.Based on our previous work, silver nanocolloids were synthesized by adopting sodium tripolyphosphate (Na5P3O10) as protecting agent and gallic acid and its derivatives as reducing agents respectively. Firstly, the experimental design (synthesis of silver nanocolloids using gallic acid as reducing agent) was optimized and uniform silver nanospheres (with an average diameter of30nm) were obtained. Furthermore, the formation mechanism of silver nanospheres was discussed. Secondly, silver nanospheres with different diameters were synthesized by adjusting reaction parameters using pyrogallic acid as reducing agent. Additionally, silver nanocrystals with multimorphologies and silver nanospheres with an average diameter of7nm were acquired by adopting gallicin and dodecyl gallate as reducing agents respectively under optimized experimental conditions.