Optoelectronic Gas Sensor Based on Few-Layered InSe Nanosheets for NO2 Detection with Ultrahigh Antihumidity Ability.

Abstract

Two-dimensional (2D) transition-metal/metal chalcogenides including MoS2, MoSe2, WS2, SnS2, etc. have shown considerable potential for the fabrication of gas sensors for NO2 detection. However, these sensors usually suffer from sluggish and incomplete recovery at room temperature, and their sensitivities are limited by presorbed O2. In this work, a novel optoelectronic gas sensor based on direct-bandgap InSe nanosheets was demonstrated. Because of the excellent photoelectric and sensing properties in few-layer InSe, detection of NO2 at room temperature was realized. Ultrahigh and reversible responses were obtained under ultraviolet (UV) light illumination, and the limit of detection (0.98 ppb) was ∼40 times lower than that observed without UV light. Furthermore, the effects of O2 and H2O molecules on sensor performance were fully studied through experiments and density functional theory. Some new mechanisms of NO2 detection in high relative humidity conditions under UV illumination were proposed, including regulation of proton transfer and induction of H2O2 reduction. In all, this work not only broadens the application field of 2D InSe, but also demonstrates the potential prospect of detecting ppb-level NO2 in complex circumstances such as human breath by using 2D material-based sensors with light activation.