3D MoSe2@MoS2 heterojunction for humidity sensors to improve sensing performance

Recently, 2D heterojunction materials have significant potential for application in humidity sensors due to their sensitive interface current regulation characteristics. Enhancing the contribution of the junction to the conductivity in the material is crucial for optimizing sensing performance. In this study, the n-n heterojunction of MoSe2@MoS2 with a unique 3D interface structure was successfully prepared using a hydrothermal method to increase the heterojunction content. The heterojunction improves the charge transfer at the interface, enhances the sensitivity of the material, and shortens the gas response/recovery time. The sensitivity of MoSe2@MoS2 with 3D heterojunction is one order of magnitude higher than that of single-phase MoSe2, and its response (recovery) time is shortened from 55 s (51 s) to 30 s (33 s) compared with single-phase MoS2. Furthermore, by optimizing the ratio of MoSe2 and MoS2 in the material, the contribution of heterojunctions to conductivity has been increased, thus enhancing the performance of gas sensing. More importantly, the sensing mechanism was deeply analyzed by exploring the changes of energy band and barrier before and after the sensor response.