Room temperature gas sensor based on rGO/Bi 2 S 3 heterostructures for ultrasensitive and rapid NO 2 detection

Bismuth sulfide (Bi 2 S 3 ) is a promising material for detecting NO 2 molecules at room temperature thanks to its narrow and tunable bandgap. However, pure Bi 2 S 3 suffers from some sensing blemish because of its low electroconductivity and poor charge transfer efficiency. Herein, we synthesized the high sensing response room temperature NO 2 detection materials composed of Bi 2 S 3 nanoflowers and reduced graphene oxide (rGO). The formed conductive network and heterojunctions between Bi 2 S 3 nanoflowers and rGO nanosheets dramatically improve the conductivity and electron transfer efficiency. The excellent rGO/Bi 2 S 3 sensor shows a high sensing response of 9.8 (approximately two times higher than that of the pure Bi 2 S 3 ) and rapid response speed of 22 s (almost half of the pure Bi 2 S 3 ) upon exposure to 1 ppm NO 2 at room temperature. Meanwhile, the rGO/Bi 2 S 3 sensor displays superb humidity-independent, selectivity, and stability. These improved NO 2 sensing behaviors can be attributed to the heterointerfaces and the hybrid effects, which accelerate charge transfer efficiency between NO 2 molecules and the surface of rGO/Bi 2 S 3 heterostructure. To enable on -line detection of ambient hazardous gas, we designed a portable wireless NO 2 detector based on rGO/Bi 2 S 3 heterostructure. This study offer an insightful guidance for improving the NO 2 sensing behaviors of metal chalcogenides.