Photoinduced synthesis of anisotropic gold nanoparticles in room-temperature ionic liquid

Anisotropic gold nanoparticles have been prepared by the photochemical reduction in the room-temperature ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF4]) without any additional capping agent. Scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and Fourier transform infrared spectroscopy have been used to characterize the as-prepared products. The results show that especial shape gold particles can be controlled by [BMIM][BF4] and reaction conditions such as reaction time and reagent concentration. The [BMIM][BF4] is a reaction medium, template, and capping agent. Under different reaction conditions, various morphologies such as sheet (triangle and hexagon) polyhedron of gold nanoparticles can be obtained. The mechanisms of photochemical reduction reaction and controlled growth of gold nanoparticles have also been discussed.