Silver nanotriangles-loaded filter paper for ultrasensitive SERS detection application benefited by interspacing of sharp edges

The strongly enhanced electromagnetic “hotspots” from the edges and tips of nanoplates are highly preferred to significantly promote the surface enhanced Raman scattering (SERS) activity. Here, Ag nanotriangles with a sharp edge of 20   nm were prepared by the reduction of AgNO 3 using N,N-Dimethylformamide (DMF) with the assistance of Polyvinyl pyrrolidone (PVP). By loading of Ag nanotriangles onto the filter paper, a flexible SERS substrate with good activity and reproducibility was obtained and the ultratrace detection of p -aminothiophenol (pATP) with a concentration as low as 10 −8   M was achieved. The sharp edges and tips boosted SERS activity was proved by the finite element method modeling of the plasmonic properties of Ag nanotriangles with different edge thicknesses (10 − 80   nm), Ag nanosheets with different tip acutances (squares and hexagons) together with Ag nanorods, nanocubes and nanospheres. The experimental and theoretical results confirmed that the interspacing created by filter paper plays an important role in enhancing the overall SERS activity. Furthermore, it is shown that the present silver nanotriangles-loaded filter paper SERS substrate can be employed to sensitive and selective detecting ultratrace military explosives picric acid (PA) of 10 −6   M.