Gold nanofluids synthesised using antioxidant catechin, its characterisation and studies on nucleation

Nanofluids are a new class of fluids where nanosized solid particles are dispersed in a liquid medium. This study aims to experimentally investigate the production of gold nanofluids using catechin (CAT), a polyphenolic compound. The characterisation of the green-synthesised nanoparticles using UV–visible spectrophotometer, differential scanning calorimeter, dielectric spectroscopy, and transmission electron microscopy, attempts to generate information to understand the properties of green-synthesised gold nanofluids. Four nanofluids were prepared by varying their concentrations between CAT and tannic acid to form gold nanoparticles (AuNP) in water. The gold nanofluids exhibited interesting thermal, surface plasmon resonance, and dielectric properties. The formation of the AuNP was studied using two different methods using transmission electron microscope and they exhibited interesting growth patterns within 1 minute. These results are significant as they shed light on the importance of the onset of the AuNP formation.