ZnO nanocrystal-coated MoS2 nanosheets with enhanced ultraviolet light gas sensitive activity studied by surface photovoltage technique

In this paper, ZnO nanocrystals and MoS2/ZnO composites were fabricated by a simple sol-gel method and ultrasonic concussion. Several characterization techniques including XRD, TEM, XPS, Raman spectroscopy and surface photovoltage were employed to explore the samples. The doping of MoS2 nanosheet into the ZnO nanocrystal composites was studied for its effect on NO2 gas-sensitivity under UV irradiation at room temperature. Compared to gas sensors developed from pure ZnO, those developed from ZnO/MoS2 exhibited higher sensitivity with a reversible response. Surface photovoltage results suggest that these desirable sensing features can be attributed to MoS2/ZnO heterojunctions and an abundance of diffusion channels which reduce the energy barrier to promote ready transference and target gas adsorption/desorption. These results offer new opportunities to fabricate composite materials for gas sensors.