One-step co-precipitation method to construct SnO quantum dots modified black phosphorus nanosheets for room-temperature trace NH3 sensing

Abstract

Black phosphorus (BP) which was an appealing two-dimensional (2D) material, had gained considerable recognition in gas sensing due to its large specific surface area, high carrier mobility and small out-plane conductivity, however, most existing studies were focused on the detection of the humidity and strongly oxidizing NOx gas. As a excellent gas sensing material, BP should have great potential in universal gas sensors. To overcome these constraints, this report proposed modifying few-layer BP nanosheets with SnO quantum dots (QDs) to detect trace NH3 at room temperature (25 °C). Compared with the BP sensor, the proposed BP-SnO-4 sensor demonstrated a significant response to 10 ppm NH3 (3.3 vs 0.8, which was among the best-reported case of BP-involving NH3 detection). The theoretical detection limit was as low as 0.8 ppt, demonstrating the considerable potential of the BP-SnO-4 sensor in the detection of NH3. The constituent ratio-optimized BP-SnO sensors exhibited higher response, less baseline drift and stronger long-term stability when compared with pure BP counterparts. Specific adsorption sites, numerous p-n BP-SnO heterojunctions and SnO nanoparticles involved passivation were primarily responsible for these improvements. This work revealed improved NH3 sensing of BP nanosheets through the incorporation of SnO QDs, thus enriching the alternative strategies of developing universal BP-based gas sensors.