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A proper design of heterogeneous molecular catalysts supported on carbon materials requires a systematic study of “metal–carbon support interactions” and their influence on catalytic activity. In this study, hybrid materials containing covalently anchored iridium N-heterocyclic carbene (NHC) organometallic complexes have been successfully prepared from oxidized and partially reduced carbon nanotubes...
Graphite (natural or synthetic) is the primary source for graphene materials preparation by the top down technology. The preparation of synthetic graphite requires temperatures above 2500°C which represents a high energy cost. Herein we demonstrate that graphene materials can be prepared directly from a pregraphitic material using two of the most widely used procedures (chemical route and solvent...
A multi-step thermal reduction process to produce graphene from graphite oxide was developed to optimize the degree of reduction, its BET surface area and its suitability as electrode in electrochemical energy storage devices. The procedure combines an initial flash pyrolysis to a temperature below 460°C and a subsequent ramp-heating treatment up to the selected final temperature. With this methodology,...
Graphene oxide (GO) and thermally reduced graphene oxide (TRGO) were covalently modified with imidazolium salts through their hydroxyl surface groups. The selective reaction of the –OH groups with p-nitrophenylchloroformate produced labile intermediate organic carbonate functions which were used for the covalent anchoring of a hydroxy-functionalized imidazolium salt. Nanohybrid materials containing...
It is demonstrated that the yield of graphene oxide sheets (GO) obtained by the sonication of graphite oxide (GrO) can be enhanced without detriment to the size of the sheets by using a simple multi step procedure. The procedure increases the total exfoliation yield by up to 15% (regardless of the GO sheet size) compared to continuous sonication and by up to 45% in the case of GO sheets of maximum...
Graphene materials containing different functional groups were prepared from a natural graphite, by means of two different oxidation methods (Hummers and Brodie). It was observed that the differences in the structure of the resultant graphite oxides (GOs) greatly affect the structure of the graphenes resulting from their thermal exfoliation/reduction. Although the oxidation of the graphite was more...
In this paper we demonstrate that the yield and size of the graphene oxide sheets (GO) obtained by sonication of graphite oxide (GrO) can be optimized not only by selecting the appropriate exfoliation conditions but also as a function of the crystalline structure of the parent graphite. A larger crystal size in the parent graphite favors GrO exfoliation and yields larger sheets in shorter sonication...
This study is a critical approach to the widespread use of the first order form of the Langmuir–Hinshelwood (LH) equation for analyzing kinetics in heterogeneous photocatalytic processes. The different kinetic protocols analyzed have been applied to the results, published in the literature, of the photocatalytic degradation of phenol in an aqueous solution by a physical mixture of TiO 2 particles...
We prepared a series of graphene-like materials by thermal exfoliation/reduction of a graphite oxide (GO) at temperatures between 127°C and 2400°C. The extent of the exfoliation and reduction of the GO at different temperatures, as well as the impact on the resultant graphene-like materials (TRGs), were studied through their chemical/structural characterization. The main oxygen loss was observed at...
Two graphene-like materials, obtained by thermal exfoliation and reduction of a graphite oxide at 700 and 1000°C, were studied as active electrodes in the positive half-cell of a Vanadium Redox Flow Battery (VRFB). In particular, that obtained at 1000°C exhibited an outstanding electrochemical performance in terms of peak current densities (30.54 and 30.05mAcm −2 for the anodic and cathodic...
The effect of the parent graphite on the structure of graphene oxide (GO) is investigated using high purity graphites with a uniform crystallite size. Our results provide direct evidence of how the size of the graphite crystal affects the oxidation process and the functionality and sheet size of the resulting GO. The important role of the crystal boundaries in the graphite with smaller crystallites...
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