Two-dimensional nanosheets have attracted tremendous attention because of their promising practical application and theoretical values. The atomic-thick nanosheets are able to not only enhance the intrinsic properties of their bulk counterparts but also give birth to new promising properties. Herein, we highlight an available pathway to prepare the ultrathin graphitic-phase C(3)N(4) (g-C(3)N(4)) nanosheets by a "green" liquid exfoliation route from bulk g-C(3)N(4) in water for the first time. The as-obtained ultrathin g-C(3)N(4) nanosheet solution is very stable in both the acidic and alkaline environment and shows pH-dependent photoluminenscence (PL). Compared to the bulk g-C(3)N(4), ultrathin g-C(3)N(4) nanosheets show enhanced intrinsic photoabsorption and photoresponse, which induce their extremely high PL quantum yield up to 19.6%. Thus, benefiting from the inherent blue light PL with high quantum yields and high stability, good biocompatibility, and nontoxicity, the water-soluble ultrathin g-C(3)N(4) nanosheet is a brand-new but promising candidate for bioimaging application.

Articles you may be interested inThe effect of ionization on the global minima of small and medium sized silicon and magnesium clusters Energies and spatial features for the rotationless bound states of He 3 + 4 ( Σ g + 2 ) : A cationic core from helium cluster ionization One-photon mass-analyzed threshold ionization spectroscopy of 1,3,5-trifluorobenzene: The Jahn-Teller effect and vibrational analysis for the molecular cation in the ground electronic state Vacuum ultraviolet mass-analyzed threshold ionization spectroscopy of hexafluorobenzene: The Jahn-Teller effect and vibrational analysis Vacuum ultraviolet mass-analyzed threshold ionization spectroscopy of p -, m -, and o -difluorobenzenes. Ionization energies and vibrational frequencies and structures of the cationsWe have performed a systematic ground state geometry search for the singly charged Si n cations in the medium-size range (nр20) using density functional theory in the local density approximation ͑LDA͒ and generalized gradient approximation ͑GGA͒. The structures resulting for nр18 generally follow the prolate ''stacked Si 9 tricapped trigonal prism'' pattern recently established for the lowest energy geometries of neutral silicon clusters in this size range. However, the global minima of Si n and Si n ϩ for nϭ6, 8, 11, 12, and 13 differ significantly in their details. For Si 19 and Si 20 neutrals and cations, GGA renders the prolate stacks practically isoenergetic with the near-spherical structures that are global minima in LDA. The mobilities in He gas evaluated for all lowest energy Si n ϩ geometries using the trajectory method agree with the experiment, except for nϭ18 where the second lowest isomer fits the measurements. The effect of gradient corrections for either the neutral or cationic clusters is subtle, but their inclusion proves to be critical for obtaining agreement with the mobility measurements in the nϭ15-20 range. We have also determined ionization potentials for our Si n neutral geometries and found that all experimental size-dependent trends are reproduced for nр19. This particularly supports our structural assignments for Si 9 , Si 11 , Si 12 , and Si 17 neutrals. The good overall agreement between the measured and calculated properties supports the elucidation of the ''prolate'' family of silicon clusters as stacks of trigonal prisms.

Controlling the synthesis of atomic-thick nanosheets of nonlayered materials is extremely challenging because of the lack of an intrinsic driving force for anisotropic growth of two-dimensional (2D) structures. In that case, control of the anisotropy such as oriented attachment of small building blocks during the reaction process will be an effective way to achieve 2D nanosheets. Those atomic-thick nanosheets possess novel electronic structures and physical properties compared with the corresponding bulk samples. Here we report Co(9)Se(8) single-crystalline nanosheets with atomic thickness and unique lamellar stacking formed by 2D oriented attachment. The atomic-thick Co(9)Se(8) nanosheets were found to exhibit intrinsic half-metallic ferromagnetism, as supported by both our experimental measurements and theoretical calculations. This work will not only open a new door in the search for new half-metallic ferromagnetic systems but also pave a practical way to design ultrathin, transparent, and flexible paperlike spintronic devices.