Preparation and Application of Two-Dimensional Ta₄C₃ MXene/Gold Nanostar Composite SERS Substrates for Thiram Detection

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Surface-enhanced Raman scattering (SERS) is a novel spectroscopic technique that enables the identification of analytes through analysis of their unique chemical signatures. Its high sensitivity, specificity, and rapid response make it a valuable tool in a range of fields, including biological detection, food safety, and environmental monitoring. However, traditional SERS nanoparticle substrates are susceptible to instability and agglomeration. In this study, Ta 4 C 3 MXene/gold nanostar (AuNSs) hybrids were prepared as SERS substrates. By optimizing the experimental conditions of AuNSs, the optimal preparation method for the Ta 4 C 3 MXene/AuNSs composite structure was identified. The addition of MXene to the Ta 4 C 3 MXene/AuNSs hybrid substrates was found to enhance the sensitivity of the composite for Raman detection, as evaluated using 4-aminothiophenol (PATP) as a Raman molecule. This improvement in sensitivity is attributed to the enhanced electromagnetic properties of the hybrid substrates, which facilitate more efficient charge transfer and enhance the Raman scattering process. The limit of detection (LOD) of Ta 4 C 3 MXene/AuNSs is 10 –9 M for PATP and 10 –7 M for thiram solutions. In addition, good reproducibility and spatial uniformity were obtained for the Raman signals of Ta 4 C 3 MXene/AuNSs. Furthermore, Ta 4 C 3 MXene/AuNSs were combined with filter paper to create paper-based SERS substrates that could be used for detection. By directly wiping the apple peel and subsequently detecting the thiram residues using Ta 4 C 3 MXene/AuNSs, the level of detection of thiram residues on the peel surface was down to 7.8 ng/cm 2 .