UV assisted ppb-level acetone detection based on hollow ZnO/MoS_2 nanosheets core/shell heterostructures at low temperature

摘要

It is challenging for current metal oxides based acetone sensors to realize excellent ppb-level acetone sensing properties at low working temperature. Herein, the hollow ZnO/MoS_2 nanosheets (HZnO/MoS_2) core/shell heterogeneous structures are originally produced. Fast gas transport channels and n-p heterojunctions are produced by the decoration of MoS_2 nanosheets on HZnO surface, resulting in high acetone response and fast response/recovery speed. Ultraviolet (UV) light is introduced to further improve acetone response and drastically reduce working temperature. The light diffraction and reflection caused by the decoration of hierarchical MoS_2 nanosheets could significantly enhance light harvesting. Hence, the excellent acetone sensing properties are obtained by the synergistic effect of UV light and HZnO/MoS_2 core/shell heterogeneous structures. Exactly, at 100 °C, the HZnO/MoS_2 possesses a stable response (1.52) to 100 ppb acetone with UV irradiation while it exhibits no response to 100 ppb acetone without UV. Even at room temperature (30 °C), UV activated HZnO/ MoS_2 still exhibits a stable response (～1.33) and fast recovery/recovery time (19s/97s) to 50ppm acetone. Furthermore, the DFT calculations are performed to demonstrate the underlying acetone sensing mechanism. The results demonstrate that UV activated HZnO/MoS_2 heterostructure could achieve trace-acetone detection at low temperature.