UV-activated room temperature single-sheet ZnO gas sensor

Room temperature sensor is a research hot for metal–oxide gas sensors. However, electron activation is a bottleneck to improve sensitivity for room temperature sensors. Here, an ultraviolet (UV)-activated gas sensor based on a single-sheet porous single-crystalline (PSC) zinc oxide (ZnO) sheet has been fabricated instead of heating activation, which works at room temperature. The PSC ZnO nanosheets were first prepared by a one-pot wet-chemical method. Then, the precursors were annealed for 2 h in air to obtain the PSC ZnO nanosheets. They were characterised by scanning electron microscopy, high-resolution transmission electron microscopy and UV–visible spectrum. Finally, the single-sheet ZnO gas sensors were fabricated by focused ion beam technology, which exhibited good responses to 1–300 ppm of ethanol. The single-sheet ZnO UV-activated sensing mechanism was also put forward to explain the excellent sensing property.