Room temperature ammonia sensor with high selectivity based on the composite materials assembled by CuO nanosheets and WS2 nanoflakes

In this work, CuO nanosheets are synthesized by one-step hydrothermal method and CuO/WS2 heterostructures are fabricated by introducing CuO doping into WS2, the preparation method was employed to enhance the performance of the gas sensor. The CuO/WS2 heterostructure nanocomposite sensor, doped with 5 % CuO, exhibited a pronounced enhancement in its response to 30 ppm of ammonia gas at ambient temperature, increasing the response value from 3.8 observed in pure WS2-based sensors to 4.7. Specifically, the response time of the CuO/WS2 heterostructure-based gas sensor decreased to 180 s, whereas the WS2-based sensor required 350 s for NH3 detection at room temperature. Furthermore, the CuO/WS2 sensor demonstrated outstanding selectivity for ammonia, maintaining stability over a 90-day test with a response fluctuation of less than 5 %. The heterojunction formed by CuO and WS2 showed superior sensitivity to NH3 compared to pristine WS2, owing to a notable enhancement in the surface catalytic effect. It also displayed sensitivity to humidity, with a response value of 6.25 at a 71 % relative humidity. At last, the gas sensing and enhanced gas sensing performance mechanisms of the composites for NH3 were elucidated. This remarkable multi-functional performance offers valuable insights for the advancement of room temperature gas sensors with diverse sensing functionalities.