Templating nanotraffic light – dynamic tricoloured blinking silver nanoclusters on a graphene oxide film

Abstract

We present a graphene oxide (GO) film as a superior substrate for the controlled anchoring and micropatterning of a blinking silver nanocluster–nanoparticle hybrid. Localised laser reduction of the GO film in the presence of AgNO₃ solution results in the controlled deposition of Ag nanoparticles (NPs) onto the reduced GO (rGO) film. Upon irradiation by blue light, some of these NPs turn into nanoblinkers (AgO/Ag_n hybrid) exhibiting dynamic tricolored fluorescence intermittency. Via the scanning laser beam, a wide variety of micropatterns with a high density of nanoblinkers are achieved on the GO/rGO film. Most remarkably, the nanoblinkers formed on GO/rGO remain vibrant even after a period of 1 year, unlike other substrates (CNT, SiO₂/Si wafer) studied. Furthermore, both the micro-patterns and tricoloured blinking behaviour are preserved upon their transfer from the GO film onto other surfaces such as glass and a PDMS film. The hybrid material can also be used to detect Rhodamine B dye where the fluorescing colour of the Ag nanoblinkers changes upon interaction with the dye. The shade of fluorescence and the blinking rate of the nanoblinkers are highly dependent on the duration of interaction between the nanoblinkers and the Rhodamine B molecules.