SYNTHESIS OF 1-5 NM GOLD NANOPARTICLES USING CTAB SURFACTANT MICELL METHOD

Abstract

This paper presents how to fabricate small gold nanoparticles chemically by using NaBH₄ as a reducing agent for HAuCl₄ precursor in the presence of CTAB. In this reaction, CTAB not only acts as a reducing agent but also acts as a surfactant needed to create uniform gold nanoparticles in size, especially gold nanoparticles with crystal structure. Gold nanoparticles were synthesized by micecell method with the CTAB concentration varying from 0.05M to 0.1M; Au^{3 +} ion concentrations ranged from 2.5 * 10^-4M to 1.5 * 10^-3 M with the survey time of two weeks. Morphology and particle size were determined by electron microscopy images transmitted through TEM, optical properties were investigated by UV-VIS absorption spectrum. The results showed that the material has size distribution from 1 nm to 5 nm and size tends to increase with storage time at room temperature. At the same time, when the precursor concentration was constant, the lower the CTAB concentration, the stronger the particle size developed over time. When the CTAB concentration is constant, the larger the amount of HAuCl₄ precursor was, the larger the particle size was. With a CTAB concentration of 0.01 M, the gold salt concentration to be selected must be 10^-3 M, the particles have a diameter of 5 nm.