Indium selenide nanosheets for photoelectrical NO2 sensor with ultra sensitivity and full recovery at room temperature

The unique properties of two-dimensional (2D) materials afford them significant prospects in the field of chemical sensors. However, these sensors still greatly suffer from the incomplete recovery due to the extremely slow molecular desorption at room temperature (RT). Herein, we demonstrate indium selenide (InSe) nanosheets exhibit excellent performances for detection of toxic NO2 at RT. The sensor delivers high sensitivity and full recovery properties under ultraviolet (UV) illumination, which is found to play an important role in enhancing the sensing performance. Remarkably, an outstanding detection limit of 10 ppb is obtained under UV activation, which is one order of magnitude lower than that (132 ppb) without UV. More importantly, the InSe sensor under UV illumination presents full and fast recovery even on exposure to repeated sensing cycles at RT. Finally, the sensor also exhibits excellent selectivity and stability at RT, indicating its great potential in NO2 detection. This impressive feature is attributed to the enhanced charge transfer and interaction between NO2 molecules and InSe caused by UV illumination. This work provides some new ideas for exploring the high-performance RT sensors based on 2D materials.