Low-operating temperature ammonia sensor based on Cu2O nanoparticles decorated with p-type MoS2 nanosheets

Abstract

The high-operating temperature and poor selectivity of metal oxide semiconductor (MOS)-based chemiresistive-type gas sensors severely limit their application in the future Internet of Things (IoT), which need a lower power consumption and a higher accurate molecular recognition ability. Here, a simple and effective modification strategy is proposed for the incorporation of Cu₂O and the two-dimensional (2D) material MoS₂via a facile hydrothermal and wet chemical method. The sensing characteristics of a series of (p–p) Cu₂O/MoS₂ nanohybrids towards ammonia (NH₃) are systematically investigated. The nanohybrid based sensor shows an excellent NH₃ sensing performance compared with the pristine Cu₂O nanoparticles in the 25–325 °C temperature range. Under an optimal low-operating temperature of 75 °C, the sensing performance for 20–100 ppm NH₃ is studied and the sensing response of the Cu₂O/MoS₂ sensor (at ∼872%) with an optimized composition for 100 ppm NH₃ is increased more than 8 times compared with the pristine Cu₂O (∼103%) under the same conditions. Furthermore, excellent selectivity for NH₃ is observed against other interferent gases. The Cu₂O/MoS₂ sensor belongs to a surface-controlled type and the enhanced sensing property of nanohybrid benefits from the superimposed effect of the p–p heterojunction formation and the elevated specific surface area at the interface between Cu₂O and MoS₂.