SnO2 nanoparticles-modified 3D-multilayer MoS2 nanosheets for ammonia gas sensing at room temperature

•SnO2/MoS2 nanocomposite ammonia sensor was prepared by hydrothermal synthesis.•SnO2/MoS2 had a flower-like structure with SnO2 nanocrystals decorated on MoS2 nanosheets.•SnO2/MoS2 exhibited remarkable sensitivity much higher than that of pure MoS2.•SnO2/MoS2 showed rapid response and recovery times and excellent selectivity.•SnO2/MoS2 sensors have potential applications in the NH3 gas-sensing field. In this work, MoS2 nanosheets decorated with SnO2 nanoparticles were prepared via a facile two-step hydrothermal method, which possesses a proposed sensing composite structure of supporting layer/sensitive dots. The SnO2/MoS2 nanocomposites exhibited an excellent sensing response (2080.36) toward 200 ppm NH3, which was ∼27.5 times higher than that of pristine MoS2 films, a fast response/recovery time (23/1.6 s) toward 50 ppm at room temperature (22℃), and outstanding selectivity to NH3 against CH4, H2, CO, H2S, and NO2 and good repeatability. The excellent gas sensing properties could be dominated by the unique thin layers assembled flower-like structures of 2D MoS2, which foster the carrier charge transfer process and the reaction to SnO2/MoS2 and NH3. These results present the SnO2/MoS2 nanocomposites promising candidate materials for high-performance NH3 gas sensing at room temperature.