Switchable operating modes enable low power consumption and improved gas sensing efficiency in MoS2/BP heterojunction

Abstract

Low power consumption and reliable response are two main requirements for gas sensors to be suitable for emerging Internet of Things and Industrial Internet applications. However, state-of-the-art inorganic chemiresistor-type gas sensors have difficulty overcoming the limitations of high-power consumption. Integrating complementary photovoltaic effect and gas sensing functions in a single heterojunction is an alternative approach. Herein, we present diode-type gas sensors based on two-dimensional heterojunction, which can switch the operating modes by adjusting the bias voltage or illumination condition. At forward bias, the sensor has a high response of 310 and good selectivity, while in self-powered mode, it exhibits an open circuit voltage of 0.36 V, a fast recovery rate (27.3 s), and low power consumption (20 nW). Furthermore, the gas sensing mechanism at room temperature was confirmed by energy potential, photoluminescence, Raman spectra measurements, and the DFT calculations before and after NO2 exposure, indicating that the electron transfer between the heterojunction and NO2 molecules was the dominant factor. The proposed gas sensor with the switchable operating modes may open new avenues for the development of advanced energy-efficient, high-efficiency gas sensing devices, and concepts.