Dual-Synthesis Ti₃C₂/SnS₂ for NH₃ Detection: High Sensitivity and Fast Response/Recovery

Ammonia (NH₃) poses significant hazards to human health and the environment, making the development of high-performance NH₃ sensors of great importance. This study combines the advantages of SnS₂ (high response to NH₃) and Ti₃C₂ (metal-level electrical conductivity and tunable surface properties) to prepare Ti₃C₂/SnS₂ heterojunctions via two methods: vacuum filtration (denoted as Ti₃C₂/SnS₂-F) and one-pot hydrothermal synthesis (denoted as Ti₃C₂/SnS₂-H) and systematically investigates their NH₃ sensing performance. Gas-sensing tests demonstrate that Ti₃C₂/SnS₂-F has a wide response range of 10-500 ppm toward NH₃. Specifically, it exhibits a response value of 11 to 500 ppm of NH₃, a fast response/recovery time of 15 s/44 s, and excellent long-term stability. Ti₃C₂/SnS₂-H demonstrates a good linear response to 10-300 ppm of NH₃ and low baseline resistance. Both materials display excellent selectivity for NH₃ and solve the problem of incomplete desorption of pure SnS₂. First-principles calculations reveal that electron transfer occurs at the interface of Ti₃C₂ and SnS₂, forming a charge-layered structure. The adsorption of NH₃ regulates the resistance by changing the carrier distribution, thereby enhancing the electrical signal. This study confirms that the Ti₃C₂/SnS₂ heterojunction is an excellent candidate material for high-performance NH₃ sensors, providing a new strategy for the design of gas-sensing materials.