Shape evolution of 3D flower-like gold microstructures from gold nanosheets via oriented attachment

Abstract

Herein, we present a shape evolution of 3D flower-like gold microstructures (3D-FLGMSs) from gold nanosheets induced by H2O2 with the presence of starch. A systematic investigation of the influence of the parameters on the size, morphology and structural evolution of 3D-FLGMSs was presented. Under the starch-stabilized environment, H2O2 plays a key role on the formation of 3D-FLGMSs as it promotes a rapid generation of small nanosheets with starch-bound {111} facet at the very early stage. At a high concentration of H2O2, the nanosheets undergo oriented attachment and transform into a large primary gold nanosheets with imperfect facet-binding. The oriented attachment (OA) and subsequent epitaxial growth of nanopetals from the imperfects turns the primary nanosheets into 3D-FLGMSs with lateral size as large as 30μm within 120min. Without starch, quasi-microspheres of gold with diameters of 5–7μm are the sole product. In addition, the 3D-FLGMSs can be employed as SERS substrates which allow the detection limit of Rhodamine 6G (R6G) at the concentration as low as 0.1μM. The developed green synthetic method utilizes non-toxic reducing and stabilizing agents while limiting the discharge of harmful chemical wastes.