Single step precursor free synthesis and characterisation of stable Au nanochains by laser ablation

TL;DR

This paper presents a simple, one-step, precursor-free laser ablation method to synthesize stable gold nanochains in ethylene glycol, with potential applications in optics and electronics due to their stability and enhanced properties.

Contribution

A novel, chemistry-free laser ablation technique for synthesizing stable gold nanochains without surfactants or reducing agents, enabling large-area transfer and enhanced dielectric and electrical properties.

Findings

Nanochains are stable, mechanically and thermally, and can be transferred to solid substrates.

The nanochains exhibit broad optical absorption across the visible spectrum.

The hybrid material shows significantly increased dielectric constant and electrical conductivity.

Abstract

In this paper we report a simple one step and one-pot synthesis of stable assembly of Au nanoparticles (diameter 8-10nm) into chains in an Ethylene Glycol medium, using only a solid metallic Au target and a pulsed excimer laser ({\lambda}=248nm). The process reported does not use any precursor, reducing agent or surfactant and thus can be described as chemistry free synthesis route. The Au nanoparticle-ethylene glycol nanochains (with unbroken lengths often more than few microns) formed in liquid medium are mechanically as well as thermally stable and can be transferred unchanged into a solid substrate which can span a large surface area. The nanochains show a broad optical absorption covering almost the complete visible spectrum. A hybrid consisting of Au nanochains and separated nanoparticles can be formed by the same method using a proper choice of the laser fluence and Ethylene Glycol /DI water concentration. The Au nanochain - Ethylene Glycol hybrid material formed by the above method shows enhanced low frequency dielectric constant (one order more than the Ethylene Glycol) and enhanced electrical conductivity even with low Au fill fraction can show enhancement up to two orders. Based on 2D-NMR experiments we suggest that the quasi-1D chain like structure forms due to the formation of dimer and trimers of Ethylene Glycol molecules that attach to the Au nanoparticles formed by the ablation process and facilitate the chain formation.