We use a contactless microwave dielectric resonator gas sensing platform to study the adsorption dynamics of NO 2 gas present in air onto a graphene surface. The use of microwaves removes the need for metal contacts that would otherwise be necessary for traditional conductivity measurements, and therefore allows non-invasive determination of NO 2 concentrations to sub parts per million. As a result, gas−metal interactions and localised graphene doping in the vicinity of metal contacts are eliminated, with the advantage that only graphene−gas adsorbate interactions are responsible for the measured signal. We show that the sensor response for all considered concentrations can be described using a surface coverage dependent Langmuir model. We demonstrate that the possible variation of the NO 2 binding energy, which is frequently considered as the main parameter, plays only a secondary role compared to the rising adsorption energy barrier with increasin…
Published in: "2DMaterials".