Water-based Controlled Synthesis Of Uniform Gold Nanoparticles And Their Properties Studies

The primary goal of this paper is to develop a simple and novel water-based strategy for the synthesis of uniform noble metals nanoparticles. In current study, ammonia, generated from ammonium bicarbonate, was used as a reducing agent for the reduction reaction to prepare uniform gold nanocrystals. Meanwhile, a tentative explanation for the reduction and growth mechanism of uniform gold nanoparticles has been proposed. Additionally, we also investigated the catalytic and SERS activities of as-prepared gold nanocrystals. And the details are as below:The pathway was based on the reduction of AuCl4– by ammonium bicarbonate in the presence of sodium stearate under hydrothermal conditions. After reacting at 160 for 3 h, 9 nm monodispersed gold nanopartciles was obtained. Experiment also results revealed that the particle sizes could be easily tuned by regulating reaction conditions. It has been experimentally verified that ammonia, generated from ammonium bicarbonate, was responsible for the reduction reaction, and the weak reducing ability of ammonium is curial for the synthesis of uniform particles.Initial experiments also revealed that the current synthesis approach could be extent to preparation of other noble metals. This is the first report on the use of ammonium bicarbonate reduction for the synthesis of nanostructured materials. And this finding enriched the applications of ammonium bicarbonate in chemistry filed. As significant improvements compared to previous commonly used method, the current method has some clear advantages including simplicity, high quality, and environmentally benign.At the same time, we also investigated the catalytic and SERS activities of as-prepared gold nanocrystals. And investigations demonstrated that the as-prepared gold particles showed good catalytic activity for the reduction of 4-nitrophenol to 4-aminophenol by excess NaBH4, and the SERS study suggested the gold nanoparticles exhibited high SERS effect on the model molecule Rhodamine 6G.Additionally, we also report a novel synthetic protocol for the synthesis of gold nanoparticles by simply mixing aqueous solution and sodium oleate. In current study, sodium oleate severed both as the reducing agent and protecting agent. It was demonstrated that the size of gold nanoparticles was well controlled by adjusting the adding amount of sodium oleate. Moreover, experiments also revealed that a good uniformity of the gold particles can be achieved using this approach.