(290h) Synthesizing Few Atom Thick Boron Based Nanostructures Isostructural to Chemically Modified Graphene Sheets

In this talk, we demonstrate a chemical synthetic route that yields a colloidal dispersion of nanosheets constituted from chemically modified boron honeycomb lattice. Such boron-based nanosheets have not been synthesized earlier and thus making available a method that yields such nanosheets forms a foundational step in addition of a new member to the growing family of nanosheets. Here we report a sonochemical method that facilitates functionalization aided layer-by-layer exfoliation of a parent crystalline material and results in an aqueous dispersion of chemically modified boron-based nanosheets. We show that the as-synthesized nanosheets are analogous to the graphene-oxide nanosheets that are formed as a result of the oxidative exfoliation process of graphite. We have utilized this dispersion to lay down the fundamental physico-chemical properties of boron-based nanosheets. This talk will present details of the ultrasonication assisted exfoliation route; morphological characteristics of the nanosheets (average lateral dimensions of 10-50 μm, average thickness of <10 nm, crumpled appearance); optical properties of the colloidal dispersion (maximum extinction coefficient of 1.08 ml mg^-1cm^-1), and the nature of surface chemical functionalization (presence of oxygen containing functional groups). We also use these fundamental properties to divulge the exfoliation mechanism and show that the pH-dependent ionization of chemical functional groups facilitate a net negative charge on the surface of nanosheets to help stabilize the colloidal dispersion.  We further show that these chemically modified boron-based nanosheets exhibit an excitation wavelength dependent fluorescence with emission peaks at ~358 nm and ~411 nm and attribute this to the heterogeneity created by the oxygen-based functional groups. This research pursuit is institutional in its merit as it presents to the scientific community an entirely new and unexplored class of nanosheets. We expect that the quasi-planar nature of these nanosheets, the capability to easily process their aqueous dispersion and the useful properties of boron atoms will open up several avenues for basic and applied research.