Room temperature gas sensor based on rGO/Bi2S3 heterostructures for ultrasensitive and rapid NO2 detection

Abstract

Bismuth sulfide (Bi2S3) is a promising material for detecting NO2 molecules at room temperature thanks to its narrow and tunable bandgap. However, pure Bi2S3 suffers from some sensing blemish because of its low electroconductivity and poor charge transfer efficiency. Herein, we synthesized the high sensing response room temperature NO2 detection materials composed of Bi2S3 nanoflowers and reduced graphene oxide (rGO). The formed conductive network and heterojunctions between Bi2S3 nanoflowers and rGO nanosheets dramatically improve the conductivity and electron transfer efficiency. The excellent rGO/Bi2S3 sensor shows a high sensing response of 9.8 (approximately two times higher than that of the pure Bi2S3) and rapid response speed of 22 s (almost half of the pure Bi2S3) upon exposure to 1 ppm NO2 at room temperature. Meanwhile, the rGO/Bi2S3 sensor displays superb humidity-independent, selectivity, and stability. These improved NO2 sensing behaviors can be attributed to the heterointerfaces and the hybrid effects, which accelerate charge transfer efficiency between NO2 molecules and the surface of rGO/Bi2S3 heterostructure. To enable on-line detection of ambient hazardous gas, we designed a portable wireless NO2 detector based on rGO/Bi2S3 heterostructure. This study offer an insightful guidance for improving the NO2 sensing behaviors of metal chalcogenides.