Temperature-induced Au nanostructure synthesis in a nonaqueous deep-eutectic solvent for high performance electrocatalysis

Structure-controlled synthesis of gold nanostructures (AuNSs) induced by temperature in a nonaqueous urea-choline chloride deep eutectic solvent (DES) is reported. Modulation of nanostructures with well-defined structures and shapes is obtained by simply varying the reaction temperature. The supramolecular soft template provided by the DES structure and its viscosity at different temperatures drives directed growth of crystalline gold and self-assembly producing star-shaped AuNSs. Additionally, the effect of AuNS shape and surface area on their catalytic activity towards the reduction of hydrogen peroxide (H2O2) has been tested. With the advantage of their high surface area and presence of high-index facets in the edge of the star arms, the star-shaped nanostructures showed superior electrocatalytic activity than other morphologies. The use of DES as a green chemistry platform for the synthesis of shape-controlled Au nanostructures with high catalytic properties may offer new avenues for fuel cell and biosensor applications.