Fabrication of 2D titanium carbide MXene/Au nanorods as a nanosensor platform for sensitive SERS detection

As an emerging label-free detection technology, surface-enhanced Raman scattering (SERS) has been used for biological detection, food safety, and environmental pollution owing to its high sensitivity, specificity and rapid response. However, traditional SERS substrates are unstable, prone to agglomeration, and demonstrate low productivity and high production cost. In this work, hybrids of a two-dimensional electron gas (2DEG) Ti3C2Tx monolayer and Au nanorods (AuNRs) were fabricated via self-assembly. Ti3C2Tx:AuNRs ratios were prepared, and each hybrid's SERS activity was evaluated through 4-aminothiophenol (pATP) detection. The Ti3C2Tx/AuNRs-1 substrate exhibited the weakest SERS performance, whereas the Ti3C2Tx/AuNRs-3 substrate had the best SERS activity enhancement, with a pATP limit of detection (LOD) of 10(-9) M. When 30 sites on substrates were selected for SERS detection, the relative standard deviation (RSD) was found to be only 7.18 %, revealing the good performance sensitivity and high reproducibility of the Raman signal. The sensitivity of Ti3C2Tx/AuNRs-3 was also assessed with respect to a hazardous chemical, 1,2-bis (4-pyridyl) ethylene (BPE), revealing an LOD of 10(-12) M. For thiram, the LOD of Ti3C2Tx/AuNRs-3 was 10(-8) M, which is considerably lower than the 1 ppm industry safety standard. A relative standard deviation RSD of 7.94 % indicates the high reproducibility and uniformity of the Raman signal of thiram for Ti3C2Tx/AuNRs-3. Compared with the LODs of 10(-5) M and 10(-6) M for commercial substrates T-SERS and Au nanorod arrays (AuNRAs), respectively, the 10-8 M LOD of our synthesized Ti3C2Tx/AuNRs indicates good sensitivity. Three kinds of pesticides were detected by Ti3C2Tx/AuNRs, and only Raman signal of thiram can be found, revealing the good selectivity for thiram. These results for Ti3C2Tx/AuNRs suggest its potential to serve as a novel SERS platform.