Self-organized formation of silver nanowires, nanocubes and bipyramids via a solvothermal method

Three kinds of silver nanostructures – nanowires, nanocubes and bipyramids – were synthesized via a simple solvothermal method by reducing silver nitrate with ethylene glycol using poly(vinylpyrrolidone) as an adsorption agent and adding different concentrations of sodium chloride (NaCl) into the solution. When a low-concentration NaCl solution is used, trace amounts of silver chloride (AgCl) appear and act as the seeds to facilitate the formation of the silver nanowires. However, when a high-concentration NaCl solution is used, large amounts of AgCl appear and mainly act as the controlling agent leading to the formation of silver nanocubes and bipyramids. Electron microscopy, X-ray diffraction and absorption spectra have been used to investigate the products, and a mechanism is proposed to interpret the morphological control of these structures. Our work provides a strategy to fabricate silver nanostructures with different shapes.