Large-scale two-dimensional titanium carbide MXene as SERS-active substrate for reliable and sensitive detection of organic pollutants

As a new class of two-dimensional material, MXene not only has the unique planar structure, electronic and optical properties, but also has a large surface area and hydrophilicity, which make them to build as potential SERS substrates with good sensitivity and stability. In this work, we reported a modified method by adjusting the ratio of HCl to LiF and reducing sonicate time to form large-sized monolayer Ti₃C₂T_x nanosheets. SERS performance of Ti₃C₂T_x was demonstrated by detecting dye molecules such as CV, R6G and MG. A remarkable enhanced effect was obtained, and Raman signals up to 10^{− 8} M could be detected. Furthermore, the relationship between SERS effects and illumination laser wavelengths of different probe molecules has been studied, the results showed the selectivity between dye molecules and the excitation wavelengths. Besides, the uniformity and stability of the substrates have been proved by mapping experiments in a large area (80 × 80 μm²). The results demonstrated that Ti₃C₂T_x nanosheets can be built as lager-sized, uniform and stable sensor for ultra-sensitive detection of organic dye pollutant molecules.