The naked-eye NH3 sensor based on fluorinated graphene

Graphene has aroused continual and tremendous interest in gas sensing applications because of its unique properties. However, the graphene-based sensors still meet limitations such as inconvenient device fabrication, sustained power supply, specific measuring equipment, etc. Here, we find that fluorinated graphene (FG) shows an obvious color change (from white to dark yellow) in the presence of NH3 which can be observed directly by the naked eye. PL measurement shows that the sensitivity of color change can reach a high value of ca. 4.05% ppm−1. The density functional theory calculations reveal that the F atoms on FG increase the adsorption ability and charge transfer of NH3 molecules, resulting in the efficient color change. This work develops a naked-eye sensor which needs no device fabrication, power supply or measuring equipment, thus, can be potentially used to manufacture a cheap, sensitive and miniaturized NH3 sensor.