Rolling up of 2D nanosheets into 1D Nanoscrolls: Visible-Light-Activated chemiresistors based on surface modified indium selenide with enhanced sensitivity and stability

Two-dimensional (2D) materials with ultra-thin structure hold much promise for application in constructing gas sensors at room temperature. Unfortunately, the production capacity of ultra-thin 2D materials with high-quality is very limited, and the prepared sensors often suffer from slow/incomplete recovery and poor long-term stability. In this study, a novel gas sensor based on carbon/oxygen functional groups-modified indium selenide (C-InSe) nanoscrolls was demonstrated. First, large-quantity and ultra-thin InSe nanosheets were obtained through electrochemical exfoliation, and assembled into nanoscrolls with heat treatment. Compared with C-InSe nanosheets sensors, the nanoscrolls devices exhibited better response intensity (381% per ppm) and faster recovery speed (∼200 s) for NO2 determination under visible light irradiation. In addition, the sensors possessed excellent selectivity, repeatability and low limit of detection (LOD) of 0.43 ppb. The superior gas-sensing performance and ambient stability can be attributed to the tubular-like framework and surface functional groups of C-InSe, and the mechanisms were investigated through experiments, calculations and simulations. Finally, the sensing chip was integrated into a portable wireless device and fulfilled NO2 monitoring in tail gas samples. This work presents a promising strategy for development of 2D materials-based sensing platform with high performance, miniaturized size, long-term stability as well as low-power consumption.