Exfoliation of black phosphorus in ionic liquids.

We report the characterization and formation of sonication-assisted liquid phase exfoliation of bulk black phosphorus (BP) crystals with the incorporation of two representative ionic liquids (ILs) ([Emim][Tf2N] and [Bmim][Tf2N]) as green dispersing media was attempted, which resulted in stable dispersion of multi-layer BP flakes with unsuspected high oxidation resistance and chemical/structural integrity due to the presence of IL layer on top of BP flakes. There are two unveiled issues for the generation of BP dispersion in ILs. First, thin films of BP flakes can be simply prepared through our approach. Because self-oxidation of BP in ambient condition can be significantly minimized in ILs, vacuum filtration step can be adopted to produce BP thin films in ambient condition. Second, the binding of IL molecules on BP flakes has been firstly demonstrated by the time-of-flight secondary ion mass spectrometry characterization. In addition to the exploitation of ILs as the green solvents with less environmental harmfulness, IL-based exfoliation of BP might be easily scalable because harsh control of atmospheric oxygen and moisture is unnecessary in this approach.

Mussel-inspired synthesis of boron nitride nanosheet-supported gold nanoparticles and their application for catalytic reduction of 4-nitrophenol.

Gold nanoparticle (AuNP)-decorated boron nitride nanosheet (BNNS) was successfully prepared through the simultaneous reduction of Au(3+) ions and the growth of AuNPs on polydopamine (PDA)-grafted BNNS. Both BNNS-AuNP and PDA-BNNS are successfully synthesized in an aqueous buffer solution (pH 8.5) in the absence of any chemical reducing agent and organic reaction, which is therefore environmentally friendly and highly beneficial for the mass production of green catalysts from 2D nanomaterials. BNNS-AuNP showed remarkable dispersion stability in aqueous media and revealed high catalytic efficiency for the reduction of nitrophenol as (4-NP) into 4-aminophenol (4-AP) within 8 min in water. The 2D structural feature of BNNS-AuNP also enables isolation and recycling of catalyst from 4-AP through the ultracentrifugation, which shows the retention of more than 60% of catalytic activity of BNNS-AuNP after five repetitions of the of recycling steps.

Fluorescent carbon nanoparticles derived from natural materials of mango fruit for bio-imaging probes.

Water soluble fluorescent carbon nanoparticles (FCP) obtained from a single natural source, mango fruit, were developed as unique materials for non-toxic bio-imaging with different colors and particle sizes. The prepared FCPs showed blue (FCP-B), green (FCP-G) and yellow (FCP-Y) fluorescence, derived by the controlled carbonization method. The FCPs demonstrated hydrodynamic diameters of 5-15 nm, holding great promise for clinical applications. The biocompatible FCPs demonstrated great potential in biological fields through the results of in vitro imaging and in vivo biodistribution. Using intravenously administered FCPs with different colored particles, we precisely defined the clearance and biodistribution, showing rapid and efficient urinary excretion for safe elimination from the body. These findings therefore suggest the promising possibility of using natural sources for producing fluorescent materials.

Boron nitride nanosheets decorated with silver nanoparticles through mussel-inspired chemistry of dopamine.

Boron nitride nanosheet (BNNS) decorated with silver nanoparticles (AgNPs) was successfully synthesized via mussel-inspired chemistry of dopamine. Poly(dopamine)-functionalized BNNS (PDA-BNNS) was prepared by adding dopamine into the aqueous dispersion of hydroxylated BNNS (OH-BNNS) at alkaline condition. AgNPs were decorated on PDA-BNNS through spontaneous reduction of silver cations by catechol moieties of a PDA layer on BNNS, resulting in AgNP-BNNS with good dispersion stability. Incorporation of PDA on BNNS not only played a role as a surface functionalization method of BNNS, but also provided a molecular platform for creating very sophisticated two-dimensional (2D) BNNS-based hybrid nanomaterials such as metal nanoparticle-decorated BNNS.