The discovery of graphene inspired ground-breaking research in the field of two-dimensional materials. The current decade, however, has seen the 2D materials landscape evolving beyond graphene. Boron, carbon’s neighbor in the periodic table, has been seeking significant attention regarding its existence in planar forms analogous to graphene. 2D Boron has been in the limelight since 2015 when the first reports on the bottom-up synthesis of ‘borophene’ nanosheets were published. Although several theoretical studies predict quasi-planar forms of boron, their experimental realization remains challenging. The apparent absence of a suitable layered 3D precursor has precluded the top-down synthesis of boron sheets by exfoliation. We present a fundamentally new perspective to this growing science of 2D Boron by proposing to use layered metal borides towards the exfoliative synthesis of boron-based nanosheets. Metal borides are layered compounds constituted of (graphene-like) honeycomb planes of boron sandwiched between hexagonal layers of metal atoms. We recently developed a chemical exfoliation strategy in which organic chelators selectively extract metal ions from layered borides in an aqueous medium. This causes delamination of boride crystals into few-layer-thick boron-based nanosheets. Detailed chemical characterization indicated that the nanosheets possessed hydride, hydroxy and oxy based functional groups. The presence of borohydride groups confers a unique chemically active character to the nanosheets to reduce several organic and inorganic molecules. Mixing these nanosheets with gold salt results in a spontaneous formation of ultra-small gold nanoparticles that subsequently anchor onto the nanosheets and form mixed-dimensional (0D-2D) heterostructures in solution. This process neither requires any reducing-stabilizing chemical nor an external inducing aide like sonication, electrochemical or thermal treatment. These nanosheets can also reduce graphene oxide to reduced graphene oxide subsequently forming quasi-2D boron-carbon nanohybrids. We present for the first time the possibility of using a boron-rich 2D material as a nanoscale reducing agent. The concurrence of reducing nature and planarity makes these nanosheets intriguing alternatives over conventional reductants. A wide range of possibilities can be realized by employing these as nanoscale reagents, and as building blocks towards assembling heterostructures with other low-dimensional systems.<br/>

Novel nanohybrids of chemically active boron based nanosheets with gold nanoparticles and graphene: Assembling mixed dimensional heterostructures in solution

2019 Fall National Meeting

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