Development of highly sensitive SnO2@ZnO based chemiresistor for Ammonia sensing

A room temperature (28°C) functional SnO2 supported ZnO (SnO2@ZnO) heterostructure based chemiresistor has been fabricated for sensing low-trace of ammonia (5–35 ppm). The decoration of SnO2 nanospheres on ZnO has been done via low-cost hydrothermal technique. The surface morphological examination done by FE-SEM reiterate the decoration of SnO2 nanospheres on the surface of ZnO. The Rietveld refinement for structural analysis of SnO2@ZnO heterostructure confirmed that both ZnO and SnO2 phases structures are present in prepared SnO2@ZnO. At lowermost concentration of 5 ppm, the sensor response of SnO2@ZnO heterostructure was 25.48 and for the maximum concentration of 35 ppm it was 159.16. The quick response and recovery time at 5 ppm were observed to be 4.05 s and 6.74 s, respectively. The response heightening supported the efficient fabrication of n-n heterojunction between the surface of ZnO and SnO2 spheres, resulting in the improved sensing performance. Also, the SnO2@ZnO chemiresistor verified high long-term stability and selectivity to ammonia as compared to other interfering gases such as methanol, ethanol, aniline, and toluene. This work opens a novel window for the development of devices that are room temperature operatable, highly sensitive and selective for quick detection of ammonia gas for its commercialization.