Boosting room-temperature NO2 detection via in-situ interfacial engineering on Ag2S/SnS2 heterostructures

The effective detection of hazardous gases has become extremely necessary for the ecological environment and public health. Interfacial engineering plays an indispensable role in the development of innovative materials with exceptional properties, thus triggering a new revolution in the realization of high-performance gas sensing. Herein, the rational designed Ag2S/SnS2 heterostructures were synthesized via a facile in-situ cation-exchange method. The coshared S atoms derived from in-situ interfacial engineering enable intimate atomic-level contact and strong electron coupling between SnS2 and Ag2S, which efficiently assist interfacial charge redistribution and transport as confirmed theoretically and experimentally. Benefiting from the high-quality interface of the heterostructures, the resultant Ag2S/SnS2 sensor delivered an ultrahigh response (286%) together with short response/recovery time (17 s/38 s) to 1 ppm NO2. The sensor also demonstrated superior sensing selectivity and reliable repeatability at room-temperature. Such excellent sensing performance could be synergistically ascribed to the junction effect and interfacial engineering of Ag2S/SnS2 heterostructures, which not only modulates the electronic properties of SnS2 but also provides abundant adsorption sites for gas sensing. This study offers guidance for engineering heterostructures with high-quality interface, which might stimulate the exploitation of other novel materials and widen their potential applications.