Edge-Selective Gas Detection Using Langmuir Films of Graphene Platelets.

Recent advances in the large-scale production of graphene have led to the availability of solution-processable platelets on the commercial scale. Langmuir-Schaefer deposition is a scalable process for forming a percolating film of graphene platelets, which can be used for electronic gas sensing. Here, we demonstrate the use of this deposition method to produce functional gas sensors, using a chemiresistor structure from commercially available graphene dispersions. The sensitivity of the devices and the repeatability of the electrical response upon gas exposure have been characterized. Raman spectroscopy and Kelvin probe force microscopy show doping of the basal plane using ammonia (n-dopant) and acetone (p-dopant). The resistive signal is increased upon exposure to both gases, showing that sensing originates from the change in the contact resistance between nanosheets. We demonstrate that Arrhenius fitting of desorption response potentially allows measurements of desorption process activation energies for gas molecules adsorbed onto the graphene nanosheets.