Synthesis characterization and catalytic action of hexagonal gold nanoparticles using essential oils extracted from Anacardium occidentale.

A new phytochemical method for the synthesis of gold nanoparticles is reported. The essential oils extracted from the fresh leaves of Anacardium occidentale are used for the reduction of auric acid to Au nanoparticles (NPs). The formation and morphology of synthesized NPs are investigated with the help of UV-visible, TEM and FTIR spectroscopy. The NPs synthesized at room temperature are mono-dispersed and hexagonal in shape with an average size of 36 nm while those prepared at higher temperature are composed of a mixture of anisotropic particles. The UV-visible absorption spectra of these anisotropic NPs show asymmetry in the longer wavelength side. The quantity of oil is an important criterion modulating the shape of NPs. Possible biochemical mechanism leading to the formation of NPs is studied using FTIR spectroscopy. The potential of synthesized Au NPs as catalyst is explored for the hydrogenation of p-nitro phenol to p-amino phenol at room temperature.