  Graphene has been recognized as a promising gas sensing material. The
response of graphene-based sensors can be radically improved by introducing
defects in graphene using, e. g., metal or metal oxide nanoparticles. We have
functionalised CVD grown, single layer graphene by applying pulsed laser
deposition (PLD) of V2O5 which resulted in a thin V2O5 layer on graphene with
average thickness of ~0.6 nm. According to Raman analysis, PLD process also
induced defects in graphene. Compared to unmodified graphene, the obtained
chemiresistive sensor showed considerable improvement of sensing ammonia at
room temperature. In addition, also the response time, sensitivity and
reversibility were essentially enhanced due to graphene functionalisation by
laser deposited V2O5. This can be explained by increased surface density of gas
adsorption sites introduced by high energy atoms in laser ablation plasma and
formation of nanophase boundaries between deposited V2O5 and graphene.
