UV-enhanced highly sensitive ammonia sensing properties based on 2DPI/In2O3 heterostructure at room temperature

The UV-enhanced sensing performance of the two-dimensional polyimide/indium oxide (2DPI/In 2 O 3 ) based sensor towards NH 3 was investigated at room temperature of 25 °C. The 2DPI/In 2 O 3 composite materials with hydrogen bond were synthesized by hydrothermal method , which is sensitive to NH 3 in the absence or presence of UV illumination. The microstructure, morphology and constituent elements of the prepared samples were characterized by SEM, TEM , XRD , XPS , FT-IR and UV–visible analysis. The as-prepared 2DPI/In 2 O 3 based sensor shows the best sensing performance compared to those of pure 2DPI and pure In 2 O 3 sensors. In terms of the sensitivity of the 2DPI/In 2 O 3 based sensor, the synergistic effect between 2DPI and In 2 O 3 leads to an enhancement of three times response of the composite sensors under UV illumination compared with the response of composite sensors without UV illumination. Particularly, the response time and recovery time of the 2DPI/In 2 O 3 based sensor towards 1 ppm NH 3 are shortened by 10 s and 20 s under 365 nm UV illumination, respectively. The significant enhancement in sensing performance is due to the formation of the heterojunction between 2DPI and In 2 O 3 . Besides, 2DPI acts as photocatalytic promoter in the 2DPI/In 2 O 3 composite. The 2DPI/In 2 O 3 based sensor is a promising candidate for UV-assisted NH 3 detection at room temperature.