Fabrication and properties of room temperature ammonia gas sensor based on SnO2 modified WSe2 nanosheets heterojunctions

In this work, a room-temperature ammonia sensor based on hydrothermally synthesized tin dioxide/tungsten selenide (SnO2/WSe2) nanostructure was demonstrated. The SnO2 nanorod was decorated on the WSe2 hexagonal nanosheets. The characterization results confirmed that the SnO2/WSe2 composite had unique microstructure, chemical composition and morphology distribution. The experimental results show that the SnO2/WSe2 composite sensor had a response of 87.07% toward ammonia gas of 5 ppm, which was 2.58 times higher than that of pristine WSe2. Meantime, the response/recovery time for the SnO2/WSe2 composite sensor was 24 s/40 s. Besides, the low detection limit of the SnO2/WSe2 sensor could reach 0.1 ppm of ammonia gas. Additionally, the sensor exhibited excellent repeatability, outstanding long-term stability, and anti-humidity interference. The greatly improvement of the SnO2/WSe2 sensor was mainly due to the special structure of the p-n heterojunction between SnO2 nanorod and WSe2 hexagonal nanosheets.