High-yield synthesis, characterization, self-assembly of extremely thin gold nanosheets in sugar based deep eutectic solvents and their high electrocatalytic activity

Abstract

A natural deep eutectic solvent (NADES) composed of simple sugars and water was used as a green, simple and cost-effective solvent for the synthesis of ultra-thin and large gold nanosheets with hexagonal and triangular shapes in the presence of Gum Arabic (GA) as a safe, nontoxic and eco-friendly stabilizer. Characterization of the synthesized gold nanosheets by the atomic force microscopy showed an average thickness of 10 ± 1 nm. The synthesis was performed perfectly efficient at room temperature without the need for any extensive treatments. Self-assembly of gold nanosheets at the liquid/liquid interface of the organic/water phase was introduced as a simple procedure to approach the formation of gold nanofilms. In this procedure ethanol was used as an inducer. Characterization of the monolayer of gold nanosheets at the interface showed that the gold nanosheets form a closed packed array with very good uniformity over a macroscopic sized area. Molecular dynamic simulation of toluene/gold nanosheets/water system confirmed that gold nanosheets have the potential to construct self-assembled structures at the water/toluene interface. A composite electrode constructed by modification of carbon ionic liquid electrode (CILE) with gold nanosheets showed a great electrocatalytic activity toward a number of biological and environmental molecules such as cysteine, epinephrine, ascorbic acid, arsenic, and hydrazine. These electrochemical results can be attributed to the extremely small thickness, high surface area and sharp edges of the synthesized gold nanosheets.