Fabrication of Ag − PTFE micro/nano structures through femtosecond laser liquid-phase processing in Ag⁺ solution for SERS sensing

Surface enhancement of Raman scattering (SERS) is a useful microanalytical tool for molecular detection in various areas, and metal − polymer composite substrates become a kind of typical flexible SERS substrates. In this work, Ag − PTFE composite structures are one-step fabricated through femtosecond laser processing PTFE in Ag⁺ solution. It simultaneously enables the fabrication of surface micro-nanostructures of PTFE and the photochemical reduction of Ag⁺ to form Ag nanoparticles decorated on the PTFE surface, finally forming the Ag − PTFE composite structures. The Ag − PTFE composite surfaces reveal foam-like porous structures, and the surface elemental composition and valence state are changed and demonstrate the reduction and decoration of Ag on the structed PTFE. The processed Ag − PTFE substrates are applied as SERS substrates to explore the ability for chemical sensing of organic molecules, indicating sensitive SERS activity, good long-term usability, mechanical flexibility, structural stability, and uniformity. Additionally, the mechanism of SERS is elucidated through FDTD electric field calculation and charge transfer path analysis. The method for fabricating metal − polymer composite structures has the advantages of simple one-step methodology, environmental friendliness, freedom from impurity introduction, and elimination of complex chemical treatments. The SERS performance indicates the great potential of metal − polymer composite structures as excellent flexible substrates for chemobiological sensing.