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

Abstract

Hydrogen Sulfide (H 2 S) is a common toxic gas released into the environment mainly during the energy production process from coal and crude oil. H 2 S 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 -Ga 2 O 3 ( β -Ga 2 O 3 /rGO) sensing layers followed by its deposition on alumina substrate by drop casting method for H 2 S gas sensing application. The structure and phase purity of the synthesized β -Ga 2 O 3 , GO and β -Ga 2 O 3 /rGO samples were characterized using X-ray diffraction (XRD). The gas sensing properties of the coated sensing layers of β -Ga 2 O 3 and β -Ga 2 O 3 /rGO were analyzed by Electrochemical Impedance Spectroscopy (EIS) at 100 °C. The gas sensing results revealed superior sensitivity and selectivity of β -Ga 2 O 3 /rGO towards H 2 S detection when compared with different interfering gases (NH 3 , SO 2 , CO 2 and CO). Nyquist plots and equivalent circuit fitting values clearly indicate that the grain boundary resistance was highly affected in H 2 S gas environment (3 ppm) compared to other interfering gases. Based on the findings the gas sensing mechanism is proposed.