Electrostatic Self-Assembly of Ti₃C₂T_x MXene and Gold Nanorods as an Efficient Surface-Enhanced Raman Scattering Platform for Reliable and High-Sensitivity Determination of Organic Pollutants

A reliable surface-enhanced Raman scattering (SERS) substrate composed of two-dimensional (2D) MXene (Ti₃C₂T_x) nanosheets and gold nanorods (AuNRs) is designed and fabricated for sensitive detection of organic pollutants. The AuNRs are uniformly distributed on the surface of the 2D MXene nanosheets because of the strong electrostatic interactions, forming abundant SERS hot spots. The MXene/AuNR SERS substrate exhibits high sensitivity and excellent reproducibility in the determination of common organic dyes such as rhodamine 6G, crystal violet, and malachite green. The detection limits are 1 × 10^-12, 1 × 10^-12, and 1 × 10^-10 M, and relative standard deviations determined from 13 areas on each sample are 18.1, 10.1, and 15.6%, respectively. In the determination of more complex organic pesticides and pollutants, the substrate also shows excellent sensitivity and quantitative detection, and the detection limits for thiram and diquat of 1 × 10^-10 and 1 × 10^-8 M, respectively, are much lower than the contaminant levels stipulated by the US Environmental Protection Agency. The MXene/AuNR composite constitutes an efficient SERS platform for reliable and high-sensitivity environmental analysis and food safety monitoring.