Synthesis of MoO3 (1D) @SnO2 (2D) core-shell heterostructures for enhanced ethanol gas sensing performance

In this paper, MoO3 (1D) @SnO2 (2D) core-shell heterostructures were synthesized by a simple two-step hydrothermal method for ethanol gas sensor. The porous SnO2 nanosheets were uniformly coated on the surface of MoO3 nanorods, increasing the specific surface area of composite. The MoO3 nanorods act as an electron transport channel and play a bridging role between SnO2 nanosheets, facilitating the transfer of electrons and increasing the base resistance of sensors. The highest response of MoO3@SnO2 (Mo:Sn = 0.9:1) at the optimum operating temperature (200 °C) to 100 ppm ethanol was 48.64, approximately 12 times higher than that of MoO3 (4.04) and 7.8 times higher than that of SnO2 (6.23). In addition, MoO3@SnO2 heterostructure (Mo:Sn = 0.9:1) shows a fast response-recovery, good selectivity and excellent stability among all composites. The test results of UV-Vis, XPS, EPR, UPS and PL illustrated that the enhanced gas sensing mechanism of MoO3@SnO2 was ascribed to its high active sites, narrow band gap, and abundant surface vacancies.