Gold functionalized MoO3 nano flakes for gas sensing applications

Molybdenum trioxide (MoO3) nano flakes (NF) with orthorhombic structure were synthesized by evaporation-condensation method using MoO3 powder as a raw material. Gold (Au) nanoparticles were used as a catalyst, preventing the growth of thick layers of MoO3. Furthermore, Au functionalization was performed by sputtering on pure MoO3 NF for a few seconds, decorating the flakes with Au nanoparticles. Chemical sensing performances were evaluated by introducing CO, NH3, Ethanol, NO2, Methanol, H2 and H2S gases in a syntetic air baseline with a relative humidity of 40% at 25 °C. MoO3 NF shows good sensitivity to Ethanol, Methanol, H2 and H2S gases. Owing to Au functionalization the devices exhibited an excellent response to H2S at an operating temperature of 400 °C: the response was 10 times higher than the pure MoO3, and the detection limit moved toward the ppb range.