Edge-Selective Gas Detection Using Langmuir Films of Graphene Platelets

Abstract

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.

Low-Humidity Sensing Properties of Multi-Layered Graphene Grown by Chemical Vapor Deposition

“…It is very likely that such defects, known as Stone-Wales defects and intrinsically ascribed to the CVD process, as well as edge defects are responsible of the weak and slow reactivity upon RH, while enhancing the reactivity upon other analytes [22,23,27]. This conclusion is strengthened by comparing the results with a previous work, where MLG was synthesized by LPE and deposited by drop-casting or through Langmuir−Schaefer technique [51,61]. In both cases, the defects originating from CVD were not present evidently.…”

“…The binding energy at the edge sites dominates over basal plane sites and induces the conduction through the edges. The contribution of the edges defects can also induce an opposite behavior towards the analytes, as observed by Nufer et al, where a p-type dopant, such as acetone, determined the increase of resistance [61].…”

Synthesis of a magnetic C@Co material via the design of a MOF precursor for efficient and selective adsorption of water pollutants

“…These results show that the adsorption of MO and CR onto C@Co are in accordance with the Langmuir model, thus suggesting that they are adsorbed in the form of a monolayer. As shown in Table1, all R L values are between 0 and 1, indicating that C@Co has a higher adsorption capacity for MO and CR than for the other dyes 52.…”

Langmuir-Blodgett Films Based on Superhydrophobic Soot

“…Langmuir-Schaefer deposition is a scalable process for forming a percolating film based on graphene platelets which can be applied for electronic gas sensing [8][9][10] and LB films can find application in many area [11].…”