SnSe₂/Ag₂Se heterostructures with an accumulation layer for rapid and sensitive detection of NO₂

Tin selenide (SnSe₂) is a potential sensing material for NO₂ detection owing to its large specific surface area and narrow bandgap. However, sensors based on pristine SnSe₂ still suffer from the disadvantages of a low response value and long response/recovery time at room temperature. Herein, SnSe₂/Ag₂Se n-n heterojunctions with an accumulation layer are fabricated via a one-step hydrothermal method. The amounts of the SnSe₂/Ag₂Se heterojunctions are effectively controlled by adjusting the Ag source content. The optimized SnSe₂/Ag₂Se sensor shows a response value of 12 to 5 ppm NO₂ at room temperature, which is 4 times larger than that of the pristine SnSe₂. The SnSe₂/Ag₂Se sensor exhibits a significantly shorter response/recovery time (21/103 s) than most of the reported two-dimensional materials at room temperature. This excellent performance is attributed to the enhanced electron transfer and the increased adsorption sites. In addition, the SnSe₂/Ag₂Se sensor exhibits good selectivity, which makes it highly suitable for practical applications.