Surface structure effect of F<sub>4</sub>TCNQ/MoS<sub>2</sub> nanocomposite heteromaterials on surface-enhanced Raman scattering

Abstract

Surface-enhanced Raman scattering (SERS) has been widely used in food and drug detection, biological and medical sensing. In recent years, the study of non-metallic SERS substrates has gradually become a hot field of SERS. Here, we investigate the modulation effect on SERS activities of 2,3,5,6-tetrafluoro-7,7,8,8-tetrachyanoquindimethylene (F<sub>4</sub>TCNQ) grown on molybdenum disulfide (MoS<sub>2</sub>) films. The different nanostructures of F<sub>4</sub>TCNQ can have an effect on the bound capability of charges transferred from the surface of MoS<sub>2</sub>, which changes the electron density distribution on the surface of the F<sub>4</sub>TCNQ/MoS<sub>2</sub> nanocomposite material. Therefore, the interface exhibits different charge localizations in the F<sub>4</sub>TCNQ/MoS<sub>2</sub> nanocomposite. The charge transfer efficiency between the substrate and the adsorbed probe molecules leads the substrate to show a different SERS sensitivity. The enhancement factor of 4-mercaptobenzoic acid (4-MBA) molecules on the most optimized 7-min F<sub>4</sub>TCNQ/MoS<sub>2</sub> nanocomposite substrate can reach <inline-formula><tex-math id="M2">\begin{document}$ 6.9\times {10}^{4} $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="3-20221958_M2.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="3-20221958_M2.png"/></alternatives></inline-formula>, and the detection limit concentration is as low as 10<sup>–6</sup> mol/L. The result of research on F<sub>4</sub>TCNQ/MoS<sub>2</sub> nanocomposite provides an effective optimization scheme of energy level regulation for SERS based on the chemical enhancement mechanism, and opens up a new way to further exploit its functional applications.