  C$_3$N is a recently discovered 2D layered material structurally similar to
graphene, which has demonstrated immense prospect for future nanoelectronics.
In this work, we have designed and investigated the operation and performance
of a C$_3$N island single electron transistor (SET) for the first time. Using
First-principles based calculations, we investigated the effect of various
molecular adsorptions on the electronic and conduction behaviour of the SET.
C$_3$N was found to be the perfect host material for capturing CO$_2$. The
charge stability diagram carries the signature of different molecules within
the SET and their presence can be uniquely identified from various line scans
and normalised differential conductance behaviour obtained from it. Our results
suggests the usefulness of such nanoelectronic structures for sensing toxic gas
molecules which can be operational over a wide temperature range with detection
sensitivity upto a single molecular level.
