Low Field Gradient and Highly Enhanced Plasmonic Nanocavity Array for Supersensitive Determination of Multiple Hazardous Chemical Residues

Surface-enhanced Raman scattering (SERS) has become the key technology for identification and quantification of various chemical molecules, biomolecules, viruses, and other pathogens in biology, electro-/photochemistry, clinical medicine, and food and environmental science fields. The great challenge in the SERS field is how to increase the coverage rate of an enhanced electromagnetic field and simultaneously reduce the electric field gradient. Here, two-dimensional Au plasmonic nanostructure arrays with a periodic one-dimensional plasmon nanocavity are fabricated by self-assembly and reactive ion etching technology, which exhibit an appreciable Raman enhancement factor of 1.02 × 108, ultrahigh and uniform EM intensity, and over 50% EM coverage rate (usually less than 10%). Benefiting from these excellent properties and photoinduced charge transfer effect, the SERS sensors not only exhibit outstanding light absorption efficiency (up to 90%) but also demonstrate excellent SERS performance in trace detection of multiple harmful chemicals with excellent limit of detection (up to about 10–10–10–12 M), low relative standard deviation (7.3–9.1%), and good dual-analyte detection ability. This work presents a solid progress toward the fabrication of a highly enhanced plasmon nanocavity with wide-range and low field gradient properties for extensive SERS application.