Highly Selective Hybrid InSe-Graphene for NO2 Gas Sensing with High Humidity Tolerance

p-type pristine InSe, pristine graphene, and the corresponding hybrid InSe-graphene gas sensor that is highly selective to NO2 have been developed. These materials are produced at an environmentally friendly temperature of 35 °C by the Liquid Phase Exfoliation (LPE) technique. Then their deposition was performed on alumina transducers for achieving chemoresistive gas sensors. X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), photoluminescence (PL), and Raman spectroscopy were used to analyze the materials. The multilayered crystalline structure is revealed by HRTEM. Studies on gas-sensing properties showed that the response of the hybrid InSe-graphene sensor to 1 ppm of NO2 is three times higher than the one of the pristine graphene sensor, whereas the pristine InSe sensor was not responsive. While under dry conditions, the response to NO2 (1 ppb) was 3.41%, under humid conditions (RH 50%), the responsiveness was significantly increased to 6.16% and to 14.42% for sensors operated at 150 and 250 °C, respectively.