Hierarchical WS<sub>2</sub>–WO<sub>3</sub> Nanohybrids with P–N Heterojunctions for NO<sub>2</sub> Detection
Yutong Han, Yang Liu, Su Chen, Xinwei Chen, Bolong Li, Wenkai Jiang, Min Zeng, Nantao Hu, Yanjie Su, Zhihua Zhou, Zhigang Zhu, Zhi Yang
Abstract
Two-dimensional (2D) transition metal dichalcogenide (TMD)-based gas sensors have received much attention due to their high sensitivity at room temperature. However, the long-term stability is limited by their poor stability against oxidation and hydration. This work develops a facile and practical strategy for the construction of reliable WS2-sensing devices under air conditions. A surface functionalization strategy for WS2 nanoflakes has been demonstrated, where WO3 nanosheets are aligned on the surface of WS2 nanoflakes via a facile sonochemical method. The synthesis method and structure–response relationship of the WS2–WO3 nanohybrid are carefully studied. The optimal device displays brilliant long-term stability and relatively stable sensing characteristics under the humidity conditions. Moreover, the WS2–WO3 sensor exhibits a remarkably enhanced response, a quick response time, and an excellent recoverability compared with the WS2 sensor. The impressive NO2-sensing performance of the WS2–WO3 nanohybrid is ascribed to the special hierarchical structure, the strong interlayer electronic coupling, and the formed p–n heterojunctions. This study offers a perspective for the structural design of TMD-based gas sensors, which exhibit not only an enhanced NO2-sensing performance but also an environmental stability.