In situ synthesis of MXene/Ag nanocomposites based flexible SERS substrates on PDMS for detection on fruit surfaces

Pesticides are often overused in production and life, which harms the environment and human health. However, the current tools for detecting pesticides are not effective enough due to lower flexibility and stability. With regards to this, we synthesized a flexible substrate of PDMS modified by MXene (Ti 3 C 2 Tx)/Ag. The MXene-noble metal composite substrate can detect 4-mercaptobenzoic acid (4MBA) at a low concentration of 1.0 × 10 −11 M. Furthermore, MXene can inhibit the oxidation of Ag nanoparticles (NPs) and efficiently localize the molecules to be tested within the hot spots. In particular, the flexibility of the substrate enables the detection of trace amounts of thiabendazole (TBZ) by collecting samples directly from uneven surfaces such as fruits and vegetables. The substrate is also capable of detecting a mixture of TBZ and 4MBA simultaneously. Using intrinsic Raman peak of PDMS as the internal standard can eliminate the influence of environmental factors on the detection results, which makes the detection results more quantitative. The resultant noble metal-semiconductor substrates show great potential applications in food safety and environmental monitoring fields.