2D/2D heterojunction of g-C3N4/SnS2: room-temperature sensing material for ultrasensitive and rapid-recoverable NO2 detection.

Heterojunction engineering plays an indispensable role in improving the gas sensing performance. However, rational heterojunction engineering to achieve a room-temperature NO2 sensing with both high response and rapid recovery is still a challenge. Herein, a 2D/2D heterojunction of g-C3N4/SnS2 is designed to improve the sensing performance of SnS2 and used for ultrasensitive and rapid-recoverable NO2 detection at room temperature. The pristine SnS2 fails to work at room temperature because of its properties of high resistivity and weak adsorption to NO2. After the combination with g-C3N4 nanosheets, the g-C3N4/SnS2-based sensor exhibits extremely high response (503%) and short recovery time (166 s) towards 1 ppm NO2 at room temperature. The improved sensing performance is primarily attributed to the increased adsorption sites and enhanced charge transfer induced by the 2D/2D heterojunctions with large interface contact area. Such achievement of g-C3N4/SnS2 2D/2D heterostructures demonstrates a promising pathway for the design of sensitive gas-sensing material based on 2D/2D heterojunction strategy.