Polyaromatic cores for the exfoliation of popular 2D materials

Two-dimensional (2D) nanomaterials have attracted interest from the scientific community due to their unique properties. The production of these materials has been carried out by diverse methodologies, the liquid phase exfoliation being the most promising one due to its simplicity and potential scalability. The use of several stabilizers allows to obtain dispersions of these 2D nanomaterials in solvents with low boiling points. Herein we describe a general exfoliation method for different 2D materials employing a biphasic water/dichloromethane system and two different (poly)aromatic hydrocarbons (PAHs). This method allows us to obtain dispersions of the exfoliated 2D materials with high concentrations in the organic solvent. Due to the low boiling point of dichloromethane, and therefore its easy removal, the obtained dispersions can be employed as additives for different composites. We corroborate that the exfoliation efficiency is improved due to the π-π and van der Waals interactions between the PAHs and the layers of the 2D materials.

Ultrasound exfoliation of graphite in biphasic liquid systems containing ionic liquids: A study on the conditions for obtaining large few-layers graphene

Herein we describe a successful protocol for graphite exfoliation using a biphasic liquid system (water/dichloromethane, DCM) containing ionic liquids (ILs; 1,3-dibenzylimidazolium benzoate- and 1-naphthoate). The use of (surface active) IL and sonication led to stable DCM/water (O/W) emulsion, which enhanced graphene formation, suppressed its re-aggregation and decreased shear/cavitation damage. The O/W emulsion stabilization by the ILs was studied by dynamic light scattering (DLS), whereas their interaction with the graphene sheets were described by Density Functional Theory (DFT) calculations. Moreover, a comprehensive investigation on cavitation-based exfoliation in the O/W systems was performed to assess the importance of operational parameters, including, the type of ultrasound processor, ultrasound power and insonation, and the influence of the exfoliation medium.

Twinned Growth of Metal-Free, Triazine-Based Photocatalyst Films as Mixed-Dimensional (2D/3D) van der Waals Heterostructures

Design and synthesis of ordered, metal-free layered materials is intrinsically difficult due to the limitations of vapor deposition processes that are used in their making. Mixed-dimensional (2D/3D) metal-free van der Waals (vdW) heterostructures based on triazine (C₃ N₃ ) linkers grow as large area, transparent yellow-orange membranes on copper surfaces from solution. The membranes have an indirect band gap (E_g,opt = 1.91 eV, E_g,elec = 1.84 eV) and are moderately porous (124 m² g^-1 ). The material consists of a crystalline 2D phase that is fully sp² hybridized and provides structural stability, and an amorphous, porous phase with mixed sp² -sp hybridization. Interestingly, this 2D/3D vdW heterostructure grows in a twinned mechanism from a one-pot reaction mixture: unprecedented for metal-free frameworks and a direct consequence of on-catalyst synthesis. Thanks to the efficient type I heterojunction, electron transfer processes are fundamentally improved and hence, the material is capable of metal-free, light-induced hydrogen evolution from water without the need for a noble metal cocatalyst (34 µmol h^-1 g^-1 without Pt). The results highlight that twinned growth mechanisms are observed in the realm of "wet" chemistry, and that they can be used to fabricate otherwise challenging 2D/3D vdW heterostructures with composite properties.

Swift Heavy Ion Irradiation as a Tool for Homogeneous Dispersion of Nanographite Platelets within the Polymer Matrices: Toward Tailoring the Properties of PEDOT:PSS/Nanographite Nanocomposites

Performance of the polymer nanocomposites is dependent to a great extent on efficient and homogeneous dispersion of nanoparticles in polymeric matrices. The dispersion of nanographite platelets (NGPs) in polymer matrix is a great challenge because of the inherent inert nature of the NGPs, poor wettability toward polymer matrices, and easy agglomeration due to van der Waals interactions. In the present study, attempts have been made to use a new approach involving the irradiation of polymer nanocomposites through swift heavy ion (SHI) to homogeneously disperse the NGPs within the polymer matrices. Poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) (

PEDOT

PSS)/nanographite nanocomposite (NC) films prepared by the solution blending method were irradiated with SHI (Ni ion beam, 80 MeV) at a fluence range of 1 × 10(10) to 1 × 10(12) ions/cm(2). XRD studies revealed that ion irradiation results in delamination and better dispersion of NGPs in the irradiated nanocomposite films compared to unirradiated films, which is also depicted through SEM, AFM, TEM, and Raman studies. In the irradiated polymer nanocomposite films, the conformation of PEDOT chains changes from coiled to extended coiled structure, which, along with homogeneously dispersed NGPs in irradiated NCs, shows an excellent synergistic effect facilitating charge transport. The remarkable improvement in conductivity from 1.9 × 10(-2) in unirradiated NCs to 0.45 S/cm in irradiated NCs is observed with marked improvement in sensing the response toward nitroaromatic vapors at room temperature. The temperature induced conductivity studies have been carried out for

PEDOT

PSS/nanographite NCs to comprehend the charge transport mechanism in NC films using the 3D Mott variable range hopping model also. The study reveals SHI as a novel method, addressing the challenge associated with the dispersion of NGPs within the polymer matrix for their enhanced performance toward various applications.