Triple-enhanced Raman scattering sensors from flexible MXene/Au nanocubes platform via attenuating the coffee ring effect

Developing substrates that combine sensitivity and signal stability is a major challenge in surface enhanced Raman scattering (SERS) research. Herein, we present a flexible triple-enhanced Raman Scattering MXene/Au nanocubes (AuNCs) sensor fabricated by selective filtration of Ti₃C₂T_x MXene/AuNCs hybrid on the Ti₃C₂T_x MXene membrane and subsequent treatment with 1H,1H,2H,2H-perfluoro-octyltriethoxysilane (FOTS). The resultant superhydrophobic MXene/AuNCs-FOTS membrane not only provides the SERS substrate with environmental stability, but also imparts analyte enrichment to enhance the sensitivity (LOD = 1 × 10⁻¹⁴ M) and reliability (RSD = 6.41%) for Rhodamine 6G (R6G) molecules owing to the attenuation of the coffee ring effect. Moreover, the triple enhancement mechanism of combining plasmonic coupling enhancement from plasmonic coupling (EM) of nearby AuNCs at lateral and longitudinal direction of MXene/AuNCs-FOTS membrane, charge transfer (CT) from Ti₃C₂T_x MXene and target molecules and analyte enrichment function provides the substrate with excellent SERS performance (EF = 3.19 × 10⁹), and allows efficient quantification of biomarkers in urine. This work could provide new insights into MXenes as building blocks for high-performance substrates and fill existing gaps in SERS techniques.