Biomorphic WO3@WS2 heterojunction composites for enhanced NO2 gas-sensing performance at room temperature

[Display omitted] •3D hierarchical WO3@WS2/BC with high specific surface area and porous structure.•Exposed S-termination of WS2 can significantly improve the gas sensitivity and selectivity for NO2.•The gas sensing performance and mechanism of WO3@WS2/BC were studied.•The excellent performance ascribed to a heterojunction and hierarchical structure. The fabrication of heterojunction composites with high activity is an effective way to enhance the room temperature (RT) gas sensing performance. However, it is still challenging for a well-designed heterojunction interface to obtain more excellent sensitivity and response-recovery rate. Herein, the hemp sticks derived from porous carbon were used as bio-templates. WO3@WS2 heterojunction composites with bio-morphology were synthesized via hydrothermal and sulfur vapor transmission methods. 3D hierarchical structure, exposed the S-termination of WS2, and the “SWO” of heterojunction interface WO3@WS2 collectively enhance the WO3@WS2/BC gas sensing performance. The results showed that the WO3@WS2/BC composite sensor exhibited remarkable selectivity to NO2 and reached a response as high as 42.9 toward 100 ppm NO2 at RT, about 3-fold higher than that of pristine WS2 nanosheets, a super-fast response/recovery time (1.6 s/37 s). The WO3@WS2/BC sensor maintained its excellent performance within twelve cycles and three months of storage in air, which has good selectivity for NO2 gas. This study provides a new line of research for developing highly sensitive NO2 detection at RT.