Experimental and theoretical investigation of synthesis and properties of dodecanethiol-functionalized MoS2

Abstract

Herein, we investigate the DDT (1-dodecanethiol) functionalization of exfoliated MoS₂ by using experimental and theoretical tools. For the functionalization of MoS₂, DDT treatment was incorporated into the conventional NMP (N-methyl pyrrolidone) exfoliation procedure. Afterward, it has been demonstrated that the functionalization process is successful through optical, morphological and theoretical analysis. The D, G and 2LA peaks seen in the Raman spectrum of exfoliated NMP–MoS₂ particles, indicate the formation of graphitic species on MoS₂ sheets. In addition, as the DDT ratio increases, the vacant sites on MoS₂ sheets diminish. Moreover, at an optimized ratio of DDT–NMP, the maximum number of graphitic quantum dots (GQDs) is observed on MoS₂ nanosheets. Specifically, the STEM and AFM data confirm that GQDs reside on the MoS₂ nano-sheets and also that the particle size of the DDT–MoS₂ is mostly fixed, while the NMP–MoS₂ show many smaller and distributed sizes. The comparison of PL intensities of the NMP–MoS₂ and DDT–MoS₂ samples states a 10-fold increment is visible, and a 60-fold increment in NIR region photoluminescent properties. Moreover, our results lay out understanding and perceptions on the surface and edge chemistry of exfoliated MoS₂ and open up more opportunities for MoS₂ and GQD particles with broader applications.