Abstract: PbS quantum dots (QDs) decorated MoO3 nanobelts were prepared by liquid phase method.The composition, structure and morphology of PbS QDs/MoO3 nanobelts were charactered by XRD, FESEM, TEM and EDS measurements.Gas sensors based on MoO3, PbS QDs and PbS QDs/MoO3 nanobelts were assembled using commercial ceramic tubes and their gas sensing properties towards NH3 were tested.The results show that gas sensors based on PbS QDs/MoO3 nanobelts have a good gas sensing response to NH3 at a relative low temperature range (20-100 ℃), and the lowest detect limit is 10 ppm.PbS QDs are uniformly dispersed on the surface of the MoO3 nanobelts, and then the formed heterojunction interface may favor for the separation of electrons and holes, which will greatly improve their electron transfer ability and gas sensing performance.

Key words: PbS quantum dots (QDs) decorated MoO3 nanobelts were prepared by liquid phase method.The composition, structure and morphology of PbS QDs/MoO3 nanobelts were charactered by XRD, FESEM, TEM and EDS measurements.Gas sensors based on MoO3, PbS QDs and PbS QDs/MoO3 nanobelts were assembled using commercial ceramic tubes and their gas sensing properties towards NH3 were tested.The results show that gas sensors based on PbS QDs/MoO3 nanobelts have a good gas sensing response to NH3 at a relative low temperature range (20-100 ℃), and the lowest detect limit is 10 ppm.PbS QDs are uniformly dispersed on the surface of the MoO3 nanobelts, and then the formed heterojunction interface may favor for the separation of electrons and holes, which will greatly improve their electron transfer ability and gas sensing performance.