Environmentally friendly etchant of in situ plasmon-activated water to improve SERS sensing of pesticides

Wet etching, the most commonly used technology in the etching industry, is simple and convenient to use, and is currently the most widely used technical method of etching. However, etching solvents used in etching technology are harmful to living organisms and the environment. Another frequently used etching technique is dry etching. Dry etching is often used to prepare array substrates for surface-enhanced Raman scattering (SERS). However, the disadvantage of dry etching technology is its complicated operation and expensive equipment required. In order to resolve the shortcomings of the above etching technologies, we propose a new technical concept, in situ vapor etching with room-temperature plasmon-activated water (PAW). The vapor of traditional deionized water (DIW) cannot perform etching of SERS-active substrates. In situ PAW vapor has characteristics of high energy and doping electrons which enable in situ PAW vapor to perform nanostructured treatment of SERS-active substrates. In addition, many properties of PAW vapor are also superior to those of DIW. Application of PAW vapor to the rhodamine 6 G (R6G) probe molecule and the imidacloprid (IM), acetamiprid (AC), and flusilazole (FL) pesticides resulted in higher signal acquisitions and lower relative standard deviations (RSDs). In our proposed innovative technique, the limit of detection (LOD) of IM was determined to be 10 ppb. Application of this technique yielded the same or better results than SERS-array substrates. This environmentally friendly etching method is an innovative technology that can provide a wider range of SERS applications.