Facile Preparation of Self-Assembled Black Phosphorus-Dye Composite Films for Chemical Gas Sensors and Surface-Enhanced Raman Scattering Performances

The research studies on the functionalization of two-dimensional (2D) materials (such as black phosphorus) are essential for the development of self-assembled nanomaterials. In this work, the composite films based on black phosphorus (BP) and dyes were prepared by Langmuir-Blodgett (LB) technology. In order to make better use of the characteristics of BP, it was exfoliated to form BP nanosheets (BPNS) and then modified with polyethyleneimine (PEI) to maintain stability. UV-vis, Raman, atomic force microscopy, and other characterizations prove that the composite films are successfully synthesized, which may be attributed to electrostatic forces and pi-pi stacking forces. Interestingly, the obtained BPNS-PEI-TPPS composite LB film shows good sensitivity to acid and alkali gas. In addition, the results of surface-enhanced Raman scattering (SERS) indicated that the BPNS-PEI-TsNiPc composite film had surface-enhanced performance for crystal violet molecules. The current work provides new clues for the preparation and development of BP-based self-assembled film materials for gas sensors and SERS.