Biopolymer-assisted synthesis of single crystalline gold disks by a hydrothermal route

This paper presents a hydrothermal method for the synthesis and stabilization of gold nanodisks with a preferential growth direction along the (111) plane inside environmentally-besign sodium alginate sol by a one-step strategy without additional reducing agent. This is carried out by transferring a sodium alginate/HAuCl4 aqueous solution into a stainless steel autoclave with a Teflon liner and heating in an oven at 100 degrees C for 30 h. Field emission scanning electron microscopy observation indicates that the gold nanodisks are predominantly hexagonal shape with micrometer-scale in diameter. Transmission electron microscope, selected area electron diffraction, and Xray diffraction analyses show that the gold nanodisks grow preferentially along the Au (111) plane. Some influential factors on the growth of gold nanodisks are discussed. The results suggest that the reactants' concentrations and reaction time are crucial to the formation of gold nanodisks and their growth mechanism is tentatively explained.