Wei Guo,Zhiquan He,Jialu Li,Li Yao,Yadong Qiao,Fadi Wang,Yuhang Wang,Fengping Wang
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 MoSe 2 @MoS 2 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 MoSe 2 @MoS 2 with 3D heterojunction is one order of magnitude higher than that of single-phase MoSe 2 , and its response (recovery) time is shortened from 55 s (51 s) to 30 s (33 s) compared with single-phase MoS 2 . Furthermore, by optimizing the ratio of MoSe 2 and MoS 2 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.
Interfacial polarization and geometrical morphology play a significant role in the attenuation of electromagnetic (EM) wave. Herein, the two-dimensional (2D)/2D heterojunction with flower-like geometrical morphology is proposed and produced, which may simultaneously provide a large contact area for achieving strong interfacial polarization and activates more sites for the possible multiple EM wave reflection and scattering. By adopting a simple two-step hydrothermal method, MoSe 2 /MoS 2 and MoS 2 /MoSe 2 inner and outer-interchangeable heterojunctions consisting of 2D MoSe 2 and MoS 2 nanosheets with flower-like geometrical morphology were successfully synthesized. The results revealed that the hydrothermal temperatures significantly impacted the flower-like geometrical morphology and MoS 2 content. By optimizing the microstructures, the designed MoSe 2 /MoS 2 and MoS 2 /MoSe 2 heterojunctions presented enhanced comprehensive EM wave absorption properties (EMWAPs), possessing strong absorption capability, wide absorption bandwidth and thin matching thicknesses. Generally, this work demonstrates that the optimized EMWAPs of designed heterojunctions mainly originate from the special interfaces and morphology configuration, which also paves a new way for the designing and synthesis of transition metal dichalcogenides-based heterojunction as a novel and desirable candidate for high-performance microwave absorbers.
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