H2S sensor based on two-dimensional MoO3 nanoflakes: Transition between sulfidation and oxidation

H2S is a flammable, explosive, and highly toxic gas; consequently, a high-performance H2S sensor based on metal oxides is required. In this study, two-dimensional MoO3 nanoflakes were synthesized through facile liquid-phase exfoliation. The thickness of the prepared MoO3 is approximately 4.2 nm. High-performance was obtained using a gas sensor based on two-dimensional MoO3 nanoflakes at a working temperature of 300 °C. In addition, the lowest detection limit can be in the range of parts per billion, and the sensor exhibits high resistance to humidity. The sensing mechanism is discussed based on the results of ex situ characterizations of the sensing process and computation of the electronic structure. The results indicate that the chemically reversible sensing process is based on the transition between sulfidation and oxidation, where sulfidation promotes the mobility of electrons and increases the conductivity of MoO3. This novel sensing mechanism provides a new perspective for the study of H2S sensors based on metal oxides.