Comparative analysis of Nafion-functionalized few-layered vs. multilayered Ti3C2Tx MXene/SnS2 nanoflowers for ammonia detection with enhanced selectivity

Abstract

Ammonia (NH₃) detection at room temperature under varying humidity conditions is crucial for environmental monitoring, industrial safety, and healthcare. However, ammonia detection remains a challenge due to the lack of sensitivity and selectivity of current room temperature based sensors. In this context, Ti₃C₂T_x MXene and flower-like SnS₂ composites were investigated for NH₃ sensing. A comparative analysis of multilayered and few-layered nanohybrid composites demonstrated that the few-layered configuration displayed a markedly enhanced response to ammonia. Its larger surface area, higher electrical conductivity, and higher number of active sites contribute to its superior gas diffusion and charge transfer properties. The composite was further functionalized with Nafion (NF) to enhance sensitivity and selectivity under humid conditions. In an optimized NF-functionalized few-layered Ti₃C₂T_x/SnS₂ sensor, we achieved a 12.11 response ratio towards 100 ppm NH₃, with a response time of 42 s and a recovery time of 156 s, as well as excellent selectivity towards interfering gases. Reliability tests conducted in humid environments confirmed the excellent operational stability and durability of the proposed sensor. These experimental results demonstrate that the developed few-layered Ti₃C₂T_x/SnS₂/NF nanohybrid composite provides a highly durable, sensitive, and selective platform for NH₃ detection in practical applications at room temperature.