Plasmon-activated water innovatively applicable for improving the performance of surface-enhanced Raman scattering

The effect of surface-enhanced Raman scattering is responsible for its sensibility, and the reproducibility of its corresponding surface-enhanced Raman spectroscopy (SERS) is evaluated using the relative standard deviation (RSD); these are two important performances in sensing. Interestingly, innovative plasmon-activated water (PAW) is a kind of pure water, which features an electron-doping structure with reduced-affinity hydrogen bonds (HBs). This review describes the innovative green applications of PAW to improve SERS performances with higher sensitivity and lower RSDs in sensing model probe molecules of rhodamine 6G (R6G) and pesticides. First, we report a facile one-step fabrication method of SERS-active Au and Ag substrates with improved SERS activity and excellent signal reproducibility using simple oxidation-reduction cycles (ORCs) performed in PAW solutions, compared to deionized water (DIW) solutions. Then, based on the designed in situ PAW, SERS enhancement of two-fold higher intensity of R6G and a corresponding low RSD of 5 %, which was comparable to and even better than those based on complicated processes shown in the literature, are encouraging. Furthermore, for SERS-active substrates with gold/silver (Au/Ag) nanocomposites prepared using galvanic replacement reactions (GRRs) based on the PAW system, the intensity and corresponding RSDs of the SERS signal of R6G were higher and lower, respectively, compared to the DIW system. Moreover, using PAW to dissolve analytes, including pesticides, was effective in improving SERS performances. Finally, environmentally friendly etchants of vapor from in situ PAW to improve SERS sensing of pesticides are discussed.