Facile preparation of self-assembled black phosphorus-based composite LB films as new chemical gas sensors

Abstract

In recent years, the researches on the modification and functionalization of black phosphorus (BP) materials have attracted more and more attention. In this study, few-layers BP nanosheets (BPNS) were prepared by a simple liquid exfoliation method. However, BPNS has the disadvantages of easy oxidation and poor stability, which will also affect the performance of BP. Therefore, 4-azidobenzoic acid was used to modify the BPNS to improve the stability of BP. In addition, 4-azidobenzoic acid modified BPNS (f-BPNS) and dye molecules can form a composite Langmuir-Blodgett (LB) film through electrostatic interaction or pi-pi stacking forces. UV-vis, Atomic force microscopy (AFM) and other characterizations were used to prove the successful preparation of the f-BPNS-dye composite LB film. It should be noted that the obtained uniform and dense composite films showed good sensitivity to acid and alkali gas. Moreover, the f-BPNS-dye composite films can still maintain high performance after 10 cycles of acid-alkali tests, indicating that the prepared films have high stability. This work provides a new direction for the preparation of new two-dimensional composite materials and their application in gas sensors.