Controllable synthesis of the homogeneous 3D Ag nanoflowers on FTO substrate for ultra-sensitive SERS detection

High-efficient SERS substrates containing dense hot spots were fabricated by assembling 3D Ag nanoflowers (AgNFs)@Au-FTO substrate by using citrate ions as the shape-guiding agent. The vertical growth of 3D AgNFs could be attributed to the synergistic effects of the concentration gradient layer of Ag + and the density gradient of the charge carrier. Combined with the simulation result of FDTD method, the enhanced SERS sensitivity and repeatability of AgNFs@Au-FTO could be attributed to the enlarged specific surface area, and the improved density of hot spots contributed by the overlap between the vertically stacked AgNSs with a high population of sharp edges.