Design of hierarchical SnSe₂for efficient detection of trace NO₂at room temperature

Layered tin diselenide (SnSe₂) has aroused widespread scientific interest by virtue of its exceptional chemical, physical, and electrical characteristics. The distinctive features of SnSe₂enable it to be an ideal candidate for efficient detection of NO₂at room temperature. Herein, hierarchical SnSe₂assembled from thin nanosheets was designed and prepared through a facile solvothermal method. An ultralow detection limit (10 ppb) and considerable NO₂sensing performance were obtained at room temperature. A sensor based on hierarchical SnSe₂demonstrated a high response value of 1200% (triple that of SnSe₂nanosheets) and short response/recovery time of 50/55 s toward 10 ppm NO₂. These remarkable sensing properties are uncommon in two-dimensional (2D) materials at room temperature. Additionally, the sensor exhibited superb selectivity, reliable reproducibility, and excellent long-term stability within 5 months. These enhanced sensing properties could be ascribed to the unique hierarchical structures, which possess large accessible space that enhances the adsorption and diffusion of gas molecules. This study offers a new strategy to improve the sensing performance of SnSe₂through rational morphology and structure design.