Highly Sensitive and Selective H 2 S Gas Sensor Fabricated with β-Ga 2 O 3 /rGO

Hydrogen Sulfide (H2S) is a common toxic gas released into the environment mainly during the energy production process from coal and crude oil. H2S causes several neurological damages to the human body which could also be fatal and thus needs to be monitored. Here, we report the incorporation of reduced graphene oxide (rGO) on β-Ga2O3 (β-Ga2O3/rGO) sensing layers followed by its deposition on alumina substrate by drop casting method for H2S gas sensing application. The structure and phase purity of the synthesized β-Ga2O3, GO and β-Ga2O3/rGO samples were characterized using X-ray diffraction (XRD). The gas
sensing properties of the coated sensing layers of β-Ga2O3 and β-Ga2O3/rGO were analyzed by Electrochemical Impedance
Spectroscopy (EIS) at 100 °C. The gas sensing results revealed superior sensitivity and selectivity of β-Ga2O3/rGO towards H2S detection when compared with different interfering gases (NH3, SO2, CO2 and CO). Nyquist plots and equivalent circuit fitting values clearly indicate that the grain boundary resistance was highly affected in H2S gas environment (3 ppm) compared to other interfering gases. Based on the findings the gas sensing mechanism is proposed.