Synthesis of rectangular plate like gold nanoparticles by in situ generation of seeds by combining both radiation and chemical methods

Synthesis of gold nanoparticles of morphology other than spheres or rods in a single step by combining the radiolytic and chemical methods has been investigated. The seeds of gold nanoparticle are generated in situ by irradiating aqueous solution containing 4×10−4 mol dm−3 gold precursor ion (AuIII), 0.1 mol dm−3 cetyltrimethyl ammonium bromide (CTAB), 0.2 mol dm−3 isopropanol, 6×10−5 mol dm−3 Ag+ and 7.2×10−4 mol dm−3 ascorbic acid (AA) at a dose rate 3.4 kGy hr−1. After a short irradiation time sufficient number of seeds were formed in the solution. AuI present in the system get adsorbed upon these seeds and then subsequently reduction of AuI to Au0 by ascorbic acid and growth of the seeds results in formation of gold nanoparticles. TEM image confirmed that plate like gold nanoparticles have been formed. The anisotropic growth of nanoparticles was found to be controlled by bilayer structure of CTAB and selective adsorption of silver ion present in the system.