Production of Two-Dimensional Layered Material through Liquid Exfoliation

Layered two-dimensional materials offer a wide range of possibilities due to their unique electrical and thermal properties ranging from semiconducting to superconducting [1]. Two-dimensional materials may be created by exfoliating transition metal dichalcogenides, transition metal oxides, or other layered compounds which include graphite, BN, BiTe3, and Bi2Se3[1]. These properties can be further increased by hybrid dispersions, composites, or single walled carbon nanotubes, allowing the materials to be potentially useful in many electronic, optical, and thermoelectric device applications. We have established, for the first time at Boise State University, the liquid exfoliation of layered materials to synthesize 2-dimensional nanoflakes. Our methods include solvent exfoliation [1], co-solvent exfoliation [2], and surfactant based exfoliation [3] to produce nanoflakes of 2-dimensional crystals. Here we present the use of co-solvent exfoliation to create hybrid nanocomposites, e.g. MoS2 and single wall carbon nanotubes with the purpose of maximizing the thermoelectric power factor (S2σDC)of the dispersion, were S is the Seebeck coefficient and σ is the electrical conductivity. [1] J. Coleman, et al., Science 331,568 (2011); [2] U. Halim, et al. Nature Communications 4, 2213 (2013); [3] R. Smith, et al. Advanced Materials 23, 2934 (2011)