No abstract

Structural flexibility in a petroleum pitch-derived carbon material has been indirectly evaluated using X-ray diffraction (XRD), immersion calorimetry and inelastic neutron scattering (INS) measurements. Exposure of the carbon material to an organic solvent (e.g., n-nonane) gives rise to a large internal rearrangement, associated with a drastic re-ordering of the graphitic microdomains. These structural changes are also associated with a high flexibility of the internal porous network, as observed by inelastic neutron scattering measurements. The internal rearrangement and the structural flexibility could be responsible for the excellent performance of this kind of activated carbons in a wide variety of adsorption processes. Last but not least, the structural characteristics of these carbon materials composed of graphitic microdomains has been used to synthesize graphene “egg-like” flakes following a simple procedure based on exfoliation with organic solvents

No abstract

This paper focuses on the development of patterned graphene/substrate by means of green nanosecond pulse laser irradiation. Monolayer graphene samples supported on a Si/SiO 2 substrate were patterned using 532 nm laser irradiation under fluence conditions ranging from 31 mJ/cm 2 and to 4240 mJ/cm 2. Raman spectroscopy was used to investigate the effect of laser irradiation on the graphene. It was found that at 356 mJ/cm 2 selective ablation of the graphene occurs. However, at fluence values above 1030 mJ/cm 2 (when damage to the substrate is observed) no ablation of the graphene takes place. In contrast, its graphenic structure was found to have been modified. Only at fluence values where the ablation of the substrate occurs, is graphene eliminated in an area almost equivalent to that of the ablated substrate. In this case, additional damage to the graphene sheet edges is produced. The increment in the number of oxygenated functional groups in these regions, as measured by XPS spectroscopy, suggests that this damage is probably caused by thermal phenomena during the ablation of the substrate.

Dip coating and Layer-by-layer have been proven as effective deposition methods. Uncrosslinked and PPD crosslinked GO membranes have been successfully fabricated. Crosslinker impact is significant in enhanced membrane separation performance. Up to 100% MB contaminant removal was achieved for crosslinked membranes. PPD-GO crosslinked membranes are suitable to reuse for multiple cycles.

This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

No abstract

The hybrid materials resulting from the covalent attachment of iridium NHC complexes, bearing 3-methyl-imidazol-2-ylidene and 3-(propyl-3-sulfonate)-imidazol-2-ylidene ligands to carbon nanotubes through ester functions, efficiently catalyzed water oxidation under chemical and electrochemical conditions. The hybrid catalyst featuring an NHC ligand with a propyl-sulfonate wingtip has shown an improved catalytic performance compared to that of the unfunctionalized material with TOF50 numbers up to 1140 h–1 using ammonium cerium­(IV) nitrate (CAN) as electron acceptor at [CAN]/[Ir] ratios higher than 2000. The positive effect of the presence of a polar sulfonate group in water oxidation has been also observed in related molecular catalysts with compound [Ir­(cod)­{MeIm­(CH2)3SO3}] being more active than [IrCl­(cod)­{MeIm­(CH2)3OH}]. The hybrid catalysts were less active than the molecular catalysts although their productivity has been improved by allowing successive additions of CAN or at least three recycling experiments. The electrochemical water oxidation by CNT-based hybrid materials resulted much more efficient. The positive influence of a water-soluble sulfonate wingtip in the hybrid catalysts has been also identified allowing with TOF values close to 22 000 h–1 at 1.4 V. The local structure around iridium atoms in the heterogeneous catalysts has been determined by means of EXAFS applied before and after water oxidation reactions. The first coordination shell is similar in both fresh and postcatalytic catalysts but a slightly increase in the oxidation state of iridium atoms is observed what can be correlated to the peaks shifts in the XPS spectra for the oxidized materials.