Characterization in 2D sulfides and graphene composites for sensing applications
In this work, we have evaluated 2D layered material composites for opto-electro-mechanical sensing applications. In particular, we have focused on TMDCs and graphite and studied the effects of chemical liquid exfoliation on the structural characteristics of the 2D layered materials, through particle size, x-ray diffraction, Raman and surface area analysis. An approach was developed to combine the solution-processed dispersion with organic and inorganic matrix materials for forming the composites. From Raman Spectroscopy of the ultra-sonicated samples, the I2D/I G>2 for graphite, and for MoS2 the difference between the A1g and E2g peak was 22.85cm-1, consistent with few layer 2D MoS2. In terms x-ray diffraction measurements of possible exfoliated materials, TMDCs and graphite, provided similar behavior when stress was induced while ultra-sonication took place, whereas aluminum powder particles, which were also analyzed for comparative purposes, tended to not follow this behavior. Once the characterization was completed, the treated samples were introduced into two dissimilar polymer matrix materials, an elastomer and an acrylic material. The graphite composite samples produced electrical signals on both of the matrices, i.e. the elastomer was combined with the graphite powder and yielded a novel composite that was tested for its opto-electro-mechanical response. The graphite elastomer based composite produced sensitivities of 0.90 V μA-1 at 7 V, 0.65 V μA-1 at 5 V and 0.39 V μA-1 at 3 V. On the other hand, the graphite-acrylic composites were tested in bending mode where the optical and electronic characterization data was gathered as a function of strain and loading density. Tunneling based mechanisms and percolation theory were used to explain the behavior of the composites in terms of the strain response as a function of the loading density. This work forms a solid foundation from which to pursue more advanced studies on the opto-electro-mechanical response of 2D layered material based composites for a wide range of applications, such as strain sensors used in health monitoring and non-destructive evaluation of materials.^
Delgado, Alberto, "Characterization in 2D sulfides and graphene composites for sensing applications" (2016). ETD Collection for University of Texas, El Paso. AAI10118797.