A novel method for rapid in situ preparation of SnS2/Ti3C2Tx composites via microwave-assisted molten salt etching and room-temperature NO2 gas sensing performance

Microwave-assisted molten salt etching enables rapid, green preparation of Ti 3 C 2 T x from Ti 3 AlC 2 in 15 min. • In situ sulfidation achieves one-step construction of SnS 2 /Ti 3 C 2 T x heterojunctions. • SnS 2 /Ti 3 C 2 T x shows a 472% NO 2 response at room temperature, with 39.73 ppb LOD and good stability. • DFT calculations reveal band regulation at heterojunctions, enhancing NO 2 adsorption via p-type channels. MXenes have attracted attention in room-temperature gas sensing due to their high conductivity and tunable surface groups. However, conventional preparation often relies on fluoride-containing etching and stepwise processes, which are not only cumbersome but also hazardous. Herein, a microwave-assisted Lewis acidic molten salt etching strategy was developed to efficiently etch Ti 3 AlC 2 within 15 min, accompanied by the simultaneous in situ growth of Sn nanoparticles on Ti 3 C 2 T x . Subsequent in situ sulfidation formed SnS 2 /Ti 3 C 2 T x heterojunctions. The material exhibits outstanding NO 2 -sensing performance at room temperature: a response of 472% toward 100 ppm NO 2 , together with excellent selectivity, long-term stability, and a low limit of detection (LOD) of 39.73 ppb. The enhancement is ascribed to the SnS 2 /Ti 3 C 2 T x heterointerfaces and abundant adsorption sites derived from the enlarged specific surface area. DFT calculations reveal that band modulation induced by work function differences creates p-type conductive channels, clarifying the sensing mechanism. This study offers a green, rapid fabrication approach for high-performance room-temperature gas sensors. Download: Download high-res image (206KB) Download: Download full-size image