Condensation effect-induced improved sensitivity for SERS trace detection on a superhydrophobic plasmonic nanofibrous mat

Although plasmonic nanofibrous mats have received much attention for SERS detection in recent years, plasmonic nanofibrous mats with superhydrophobicity are rarely reported due to the hydrophilic characteristics of Au and/or Ag nanocrystals. The analyte solution usually spreads randomly over a large area based on this hydrophilic characteristic of Au and/or Ag nanocrystals, which severely restricts the improvement of SERS detection sensitivity. Here, we prepared superhydrophobic polymer nanofibers decorated with noble metal nanoparticles with largerly improved sensitivity for SERS detection. The superhydrophobic characteristic of the polymer/noble metal hybrid nanofibrous mat can overcome the random spreading of the analyte aqueous solution over the substrate and enriches the droplet containing analyte molecules on a very small area where a strong plasmonic electric-field was used to carry out SERS detection. About a 14-fold decrease in spot area on our superhydrophobic substrate leads to a corresponding 8-fold improvement in the lowest detection concentration for rhodamine 6G molecules, as compared to a non-superhydrophobic substrate.