Galvanic replacement of mesh-like Ag nanosheets at an air-water interface

Ag nanosheets consisting of mesh-like nanowires were prepared by irradiating an adsorbed monolayer of Ag nanoparticles with UV light at the air-water interface. Ag nanosheets on water were employed in a galvanic replacement reaction with HAuCl4, and their morphological evolution was investigated using TEM. Mesh-like nanowires in these nanosheets were transformed into swollen, two-dimensional, interconnected, Ag-Au nanotubes while maintaining their mesh-like structure. Interestingly, these swollen nanotubes were subsequently transformed into continuous, thin Au nanowires with interconnected structures, rendering the Au nanosheets conductive. Further, we also demonstrated that galvanic replacement of Ag nanosheets on a solid substrate yields discrete Au nanoparticles; thus, the air-water interface is essential for creation of continuous mesh-like Au nanowires.