Preparation of the Au nanoparticles using NaHCO3 as a reducing agent

Abstract

In this paper, the Au nanoparticles were synthesized by polyol process with NaHCO3 (sodium hydrogen carbonate) as a reducing agent. Utilizing NaHCO3 in polyol process achieved the low reaction temperature and the short reduction time. Decomposition of NaHCO3 serves carbonate ions (CO32-) and a small amount of H2O which dissolves the carbonate ions in. Carbonate ions increase pH of the mixtures and accelerate the reduction rate of AuCl4-. In our experiments, the effects of the NaHCO3/Au weight ratio and the PVP concentration on the reduction rate of AuCl4- and the particle size of the Au nanoparticles were investigated. The NaHCO3/Au weight ratio was varied to 10, 5, 3, 1 and 1/5. The reduction rate of AuCl4- was observed by the speeds of the color changes of the mixtures. UV-vis spectra and TEM images indicated that the size of the Au nanoparticles was controlled by the NaHCO3/Au weight ratio and the PVP concentration.