Highly sensitive detection of cationic pollutants on molybdenum carbide (MXene)/Fe2O3/Ag as a SERS substrate

Abstract

Recent studies reported that the two-dimensional transition-metal carbides (MXenes) present promising results for surface-enhanced Raman spectroscopy (SERS) application, permitting sensitive detection of analyte molecules thanks to rich surface chemistries, surface plasmon resonances, and electrical features. However, Mxene materials, especially Mo-based ones, still suffer from low concentrated sensing activity and lack specific sensing suited to surface chemistries. To overcome those issues, for the first time, we propose a simple and scalable approach to fabricate Mo2CTx/Fe2O3/Ag (MFA) hybrid nanostructure via the hydrothermal treatment of MXene and Fe2O3, and subsequent in-situ decorated of Ag NPs via seed-mediated growth processes. As-prepared MFA presents a 1 x 10-9 M detection limit with a 1.46 x 106 enhancement factor for cationic MB molecules. Here, in addition to the contribution of the electromagnetic enhancement mechanism due to the presence of Ag, the chemical enhancement mechanism also comes into play as a result of the specific binding of the cationic molecule, MB, to the negatively charged MXene surface. This result is also observed for harmful cationic molecules found in wastewater such as CTAC and arsenic. MFA exhibits a low detection limit for CTAB, where a very low concentration of 0.075 M was achieved probably owing to its cationic character. Last but not least, the MFA hybrid nanostructure shows promising results for arsenic detection in tap water with 10 & mu;g/L. Overall, an as-prepared MFA is a promising option for creating a SERS-active surface that can be customized for particular uses, due to its adjustable surface chemistries and elevated charge carrier densities, while also being low-cost and simple to manufacture.