Generalized green synthesis of diverse LnF3-Ag hybrid architectures and their shape-dependent SERS performances

This paper reports the generalized green synthesis of a series of LnF(3)-Ag (Ln = Nd, Sm, Eu, Tb) hybrid architectures with tunable shape, surface features, and composition. These intriguing hybrid structures are formed through the uniform magnetron sputtering of silver (Ag) nanoparticles on LnF(3) micro-supporters. The LnF(3)-Ag surfaces are corrugated with high-density and numerous Ag nanogaps (which can serve as Raman active `hot spots', to amplify the Raman signal), providing the sound reliability and reproducibility of Raman detection. We find that the special spindle structure of TbF3-Ag particles display the highest Raman enhancement efficiency compared to disk-, pancake-, peanut-, and rice- like structures. These experimental observations are in good agreement with the theoretical calculation by using the three-dimensional finite difference time domain (3D-FDTD) method. It is found that the produced LnF(3)-Ag composites are robust and efficient SERS substrates for high sensitivity detection of molecular adsorbates. Raman results show that the limit of detection (LOD) for crystal violet (CV), p-aminothiophenol (PATP) and Rhodamine 6G (R6G) of the optimized TbF3-Ag spindles substrate are as low as 10(-11) M, 10(-10) M and 10(-14) M, respectively, which meets the requirements for ultratrace detection of analytes. In addition, the LnF(3)-Ag substrates are stable and can be produced with high reproducibility, which shows great potential applications for universal SERS substrates in practical SERS detection.