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

摘要

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 30 mu m within 120 min. Without starch, quasi-microspheres of gold with diameters of 5-7 mu m 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 0.1 mu M. The developed green synthetic method utilizes non-toxic reducing and stabilizing agents while limiting the discharge of harmful chemical wastes.