Nitrogen Dioxide Gas Sensor Based on Liquid-Phase-Exfoliated\nBlack Phosphorus Nanosheets

Abstract

Black\nphosphorus (BP) nanosheets represent a promising class of\ntwo-dimensional (2D) materials for nitrogen dioxide (NO₂) sensing, but its practical application is limited by complex preparation\nprocesses. In this paper, we present an ultrasensitive and selective\nchemiresistive NO₂ sensor based on liquid-phase-exfoliated\nBP nanosheets. The unique combination of probe sonication and ice-water\nbath sonication is capable of producing BP nanosheets of various controllable\nsizes. Sensing characterization shows that the BP nanosheet-based\nsensor exhibits a large sensing response of 88%, a high selectivity,\nand a full recovery toward 100 ppb NO₂ gas at room temperature,\nwhich represents a substantial improvement over recently reported\ndesigns. The proposed preparation method for nanosheets with tunable\ngas-sensing properties is instrumental to the practical applications\nof BP toward high-performance, portable, and ubiquitous NO₂-sensing applications.