In Situ Crumpling of Gold Nanosheets into Spherical Three-Dimensional Architecture: Probing the Aggregation-Induced Enhancement in Photothermal Properties.

Assembling two-dimensional noble metal nanocrystals into a three-dimensional mesoporous structure is of great value to solve the re-stacking issue for the practical application, which still remains a challenging technique. Herein, we report the one-pot fabrication of gold (Au) nanostructures with a crumpled paper ball-like morphology (Au NCPBs). The success of current work relies on the use of glutathione to crumple the branched Au nanosheets formed during the early stage, into spherical three-dimensional architecture, where the nanosheets are assembled with a mesoporous structure without intimate contact. When working as the agent toward photothermal conversion, the Au NCPBs exhibit enhanced photothermal conversion efficiency (η = 19.9%), as compared to that of flat and wrinkled Au nanosheets. Such an enhancement should be owing to the aggregation-induced effect, where the shortened inter-sheet distance contributes to an increased coupling between the plasmon oscillations/fields of the interacting Au nanosheets. The present study offers a feasible strategy to create spherical architecture of crumpled Au nanosheets and validates their structural advantage in photothermal applications, which could be potentially extended to other metals or alloys.