Investigation of shape controlled silver nanoplates by a solvothermal process

The shape control and growth process of silver nanoplates formed by a solvothermal solution approach was investigated by placing a mixed solution containing silver nitrate, poly(vinyl pyrrolidone) (PVP), N,N-dimethylformamide (DMF) or ethanol in an autoclave and examined the products under various reaction conditions. The formation process in ethanol proceeds slowly taking more than 10h to form a suspension of hexangular single plates, which are no more than 50nm in edge length, while the process in DMF is relatively rapid forming large single plates within 2-4h. These separate nanostructures can be fused extensively toward the edge region to form a larger mass. The different sized plates fused together grew to large films or belts but maintained the same thickness. Apart from the reaction time and temperature, appropriate amounts of PVP and DMF were also found to be critical to the shape control. Relatively small triangular plates with average edge lengths of 20-50nm could be separated easily from the product. UV-vis absorption spectroscopy showed that these nanoplates exhibit a strong absorption band from 470 to 630nm. Compared with other methods, our synthesis is mass-productive, rapid and easily operated. The newly formed silver nanoplates may have many potential applications in the biological, chemical, and electrical industries.