Design of highly responsive chemiresistor-based sensors by interfacing NiPc with graphene

Highly sensitive and selective gas-sensing materials are critical for applications ranging from environmental monitoring to breath analysis. A rational approach at the nanoscale is urgent to design next-generation sensing devices. In previous work, we unveiled interesting charge transfer channels at the interface between p-type doped graphene and a layer of nickel phthalocyanine (NiPc) molecules, which we believe could be successfully exploited in gas sensing devices. Here, we have investigated the graphene-NiPc interface’s response to adsorbed gas molecules via first-principles calculations. We focused on NH3 and NO2 as test molecules, representing electron donors and acceptors, respectively. Notably, we identified the Ni dz2 orbital as a key player in mediating the charge transfer and affecting the charge carrier density in graphene. As a proof-of-concept, we then prepared the graphene-NiPc system as a chemiresistor device and exposed it to NH3 and NO2 at room temperature. The sensing tests revealed excellent sensitivity and selectivity, along with a rapid recovery time and a remarkably low detection limit.