Abstract
A complete green chemical reaction between aurochloric acid and tea polyphenols resulted in the reduction of Au 3? ? Au 0 . The reaction was carried out in a Teflon-coated bomb digestion vessel at 200 C. It was observed that with increasing the reaction time from 1 to 5 h, the shape of the nanoparticles changed from spherical- to rod-like structures. The reaction was followed with the help of UV-vis spectrometer, which showed a single absorption peak at 548 nm for 1-h reaction product and two peaks for a 5-h reaction product at 533 and 745 nm cor- responding to the transverse and longitudinal surface plasmon resonance bands. Microstructures obtained from transmission electron microscope revealed that the samples obtained after 1-h reaction are predominantly spherical in shape with an average size of 15 nm. Whereas samples obtained after 5 h of reaction exhibited rod-like structures with an average size of 45 nm.
Highlights
Synthesis of gold nanoparticles (Au NPs) has drawn the attention of researchers because of their extensiveS
It proves that the tea polyphenols are very essential for the reduction of Au3? ions to Au NPs
We have successfully demonstrated a complete green chemical route for the synthesis of Au NPs with different shapes
Summary
Ram Materials Science Centre, Indian Institute of Technology, Kharagpur 721 302, India applications in the development of new technologies in areas such as chemistry, catalysis, electronics, medicine and biotechnology [1,2,3] As both size and shape of Au NPs affect optical and electronic properties, a number of methods have been reported for the preparation of Au NPs with varying sizes and shapes [4,5,6]. Many of the synthetic routes for development of nanomaterials use toxic reagents that make them unsuitable for biological use and have adverse effect on the environment These methods are expensive as they require high energy, long time and sophisticated equipments to carry out the reactions. Green nanotechnology uses biomolecules present either in plant extracts or microorganism as novel reducing and capping agents They suffice as environmentally friendly routes and as economically sustainable alternatives to chemical and physical methods
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