No abstract

Black phosphorus (BP) is one of the most attractive graphene analogues, and its properties make it a promising nanomaterial for chemical sensing. However, mono- and few-layer BP flakes are reported to chemically degrade rapidly upon exposure to ambient conditions. Therefore, little is known about the performance and sensing mechanism of intrinsic BP, and chemical sensing of intrinsic BP with acceptable air stability remains only theoretically explored. Here, we experimentally demonstrated the first air-stable high-performance BP sensor using ionophore coating. Ionophore-encapsulated BP demonstrated significantly improved air stability. Its performance and sensing mechanism for trace ion detection were systematically investigated. The BP sensors were able to realize multiplex ion detection with superb selectivity, and sensitive to Pb(2+) down to 1 ppb. Additionally, the time constant for ion adsorption extracted was only 5 s. The detection limit and response rate of BP were both superior to those of graphene based sensors. Moreover, heavy metal ions can be effectively detected over a wide range of concentration with BP conductance change following the Langmuir isotherm for molecules adsorption on surface. The simplicity of this ionophore-encapsulate approach provides a route for achieving air-stable intrinsic black phosphorus sensors that may stimulate further fundamental research and potential applications.

In this paper, we demonstrated a room-temperature acetone gas sensor based on tin dioxide (SnO 2 )-reduced graphene oxide (RGO) hybrid composite film. The SnO 2 -RGO composite film sensor was fabricated on PCB substrate with rectangular-ambulatory-plane interdigital microelectrodes by using a facile hydrothermal method. The presence of small-sized SnO 2 nanoparticles on RGO sheets was 10 characterized by SEM, XRD and BET measurement, demonstrating well-structures without irreversible restacking of sheets and agglomeration. The sensing properties of the SnO 2 -RGO hybrid film sensor were investigated by exposing to various concentration of acetone gas at room temperature. It was found that the presented sensor exhibited not only excellent response to acetone gas, but also fast response-recovery time and good repeatability, exhibiting the unique advantages of SnO 2 -RGO hybrid composite as a 15 building block for sensor fabrication. The gas response of the SnO 2 -RGO hybrid composite was about 2-fold higher than that of the pure RGO film, and the possible sensing mechanism was mainly attributed to the high surface area, three-dimensional porous nanostructure and special interactions between RGO sheets and SnO 2 nanoparticles.