Self-powered and flexible gas sensor using defect-engineered WS2/G heterostructure

Two-dimensional (2D) Transition Metal Dichalcogenides (TMDCs) are considered leading candidates for ultrathin and wearable gas sensors, owing to their unique properties, including high sensitivity to gas adsorption and flexibility. However, the ongoing Internet of Things (IoT) revolution further puts forward requirements of self-contained power for future gas sensors, and the study of the self-power performance of 2D TMDCs gas sensors to date has lagged behind other characteristics. Here, we demonstrate a photovoltaic self-powered gas sensor based on the defect-engineered WS2/G heterostructure, exhibiting excellent sensing performances, including ultra-sensitivity, and fast response. Defects induced by the ion irradiation engineer the homogeneous WS2/G into a heterogeneous WS2–0.2/G-WS2/G forming a Schottky diode with photovoltaic functions. Driven by the indoor light (500 Lx, 0.9 mW/cm2), this WS2–0.2/G-WS2/G heterostructure identifies NO2 gas by the positive change of the photocurrent and the limit of detection (LOD) toward NO2 is 50 ppb with a response time of 110 s. The sensing performance of the defect-engineered heterostructure remains stable even after 1000 cycles of bending, confirming the application potential as a flexible device. This work presents an efficient strategy for preparing the self-powered gas sensor based on two-dimensional materials, meeting the emerging Internet of Things requirements.