The study of the structural, sorption, and electrochemical properties of a natural composite shungite

Tarasevich, Yu. I.; Бондаренко, С. В.; Polyakov, V. E.; Zhukova, A. I.; Ivanova, Z. G.; Luk’yanova, V. V.; Malysh, G. N.

doi:10.1134/s1061933x08030137

Cited by 8 publications

(7 citation statements)

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“…The consequent revelation that the fundamental carbon component forming the microstructure of this raw material can also be given by nano-sized agglomerates of graphene-like systems 15 , 17 – 25 , is feeding an increasing scientific and technological interest towards this fascinating natural carbon allotrope. In fact, the SH-derived carbon is nowadays object of many exciting speculations, and high attention is paid to identifying the technological areas in which its properties can be exploited to the best 16 , 26 – 33 .…”

Section: Introductionmentioning

confidence: 99%

Graphene platelets from shungite rock modulate electropolymerization and charge storage mechanisms of soft-template synthetized polypyrrole-based nanocomposites

Politi

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Tamburri

et al. 2018

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We report here on soft-template electropolymerizations of polypyrrole (Ppy)-based nanocomposites triggered by graphene platelets (GP) from shungite (SH) rocks. A properly designed procedure for an efficient extraction of graphene platelets from SH powders is established to produce remarkable graphene materials in a low oxidation state and with a high electrical conductivity (1490 S cm−1). By using positively and negatively charged templating surfactants the role played by the graphene units on the electropolymerization reactions is pointed out by SEM, EDX, TEM, SAED, XPS and Raman spectroscopy. The morphological/structural characterizations highlight that GP from SH have a surface chemistry suitable for selective and mutual interactions with the growing Ppy chains. CV and galvanostatic charge/discharge measurements evidence that GP improve the transport of both electrons and ions within the bulk material by means of a synergistic action with the polymer phase. This cooperative behavior induces an enhancement of the specific capacitance up to 250 F g−1 at 2 A g−1. The Ppy-GP materials produced following the settled protocols result to be appropriate for fabricating multifunctional charge transport and storage electroactive systems.

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Section: Introductionmentioning

confidence: 99%

Graphene platelets from shungite rock modulate electropolymerization and charge storage mechanisms of soft-template synthetized polypyrrole-based nanocomposites

Politi

Carcione

Tamburri

et al. 2018

Sci Rep

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“…A slight step is noted in the initial relative pressure range p/p s = 0-0.3 on the calorimetric curve for the dependence of the differential heat of adsorption on the amount of water adsorbed on the shungite, which corresponds to a differential heat of adsorption of 78 kJ/mol and an interaction of the water molecules with vicinal hydroxyl groups of the silica gel surface. Then, we find a decrease in the differential heat of adsorption due to microswelling of the adsorbent [10]. The smooth rise of the isotherm corresponds to microswelling on the adsorption curve (Fig.…”

Section: Discussion Of the Calculation Resultsmentioning

confidence: 94%

“…A specific interaction is not characteristic for nitrogen molecules. The existence of two types of sites relative to nitrogen adsorption in the initial occupation region may be attributed to the adsorption of nitrogen molecules in micropores with diameter 2 and 3.5 nm, which found in a complex structure-adsorption experiment [10].…”

Section: Discussion Of the Calculation Resultsmentioning

confidence: 99%

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Estimation of the energetic nonhomogeneity of the surface of oxide and carbon materials

et al. 2008

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The molecular statistical method for evaluating the distribution of active sites of various adsorbents relative to their energies has been improved. This method is used not only for the treatment of experimental data on the adsorption of hydrocarbons on various adsorbents, which is the usual procedure, but also data on the adsorption of polar water and methanol molecules on the active sites of adsorbent surfaces. Two types of active sites differing in energy have been shown to exist on the surface of graphitized carbon black, the complex shungite carbon/mineral adsorbent, and modified Silochrom. Chromatographic, calorimetric, and structural adsorption data were used to establish the relationship between the observed maxima of the energy distribution function of the adsorption sites with concrete adsorption sites or pores of the surface, on which the molecules are adsorbed.Adsorbents and catalysts, by their nature, are energetically nonhomogeneous. We distinguish between structural and chemical nonhomogeneity. Structural nonhomogeneity for monophase adsorbents is a consequence, for example, of the energy inequivalence of various crystal faces as, for example, in the case of talc [1], the existence of different types of dislocations on the surface of microcrystals, the existence of surface micropores, a breakdown of orderedness in the deposition of adjacent layers in the structure, and the domain distribution of isomorphic impurities.Complex adsorbents such as alumosilica gels, mountain leather-montmorillonite silicates, and carbon-mineral adsorbents are also commonly used in adsorption and catalytic processes. Each of the phases in these adsorbents has a characteristic set of structural-energetic sites of nonhomogeneity, while the boundary of the two adjacent disperse materials is a special type of structural heterogeneity, which plays a role in heterogeneous catalysis.Chemical heterogeneity is related both to the different chemical composition of the adsorbent, which predetermines the type of active adsorption sites, and to their coordination number. Such heterogeneity is characteristic for silica gels with isolated, vicinal, and silanediol groups on the surface [2], for alumina gels with characteristic tetrahedral and octahedral coordination of the surface aluminum atoms, and, correspondingly, different activity of the bound hydroxy groups [3], and for carbon adsorbents with characteristic carboxyl, phenol, and hydroxyl active sites [4].Various physical chemical methods are employed for studying both structural and chemical nonhomogeneity. However, theoretical thermodynamic analysis based on experimental adsorption and chromatographic data remains the most reliable method permitting determination of the quantitative characteristics of surface nonhomogeneity. Various workers [5][6][7] 0040-5760/08/4405-0325

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“…(7) and (10) two different adsorption systems were chosen. In one the adsorption system described the adsorption of nitrogen at T = 77 K on the natural material shungite [14]. This isotherm was described in terms of Eqs.…”

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Modified equation for the isotherms of multilayer adsorption

2009

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UDC 541.183:543.42 V. V. Kutarov, R. M. Dlubovskii, and V. N. Shevchenko A four-parameter equation for the description of multilayer adsorption isotherms of IUPAC type II classification is proposed. The equation permits the description of the isotherm of multilayer adsorption over the whole range of relative adsorbate pressure in the bulk phase. The equation is obtained strictly analytically within the framework of the basic postulates of BET theory.

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The study of the structural, sorption, and electrochemical properties of a natural composite shungite

Cited by 8 publications

References 1 publication

Graphene platelets from shungite rock modulate electropolymerization and charge storage mechanisms of soft-template synthetized polypyrrole-based nanocomposites

Graphene platelets from shungite rock modulate electropolymerization and charge storage mechanisms of soft-template synthetized polypyrrole-based nanocomposites

Estimation of the energetic nonhomogeneity of the surface of oxide and carbon materials

Modified equation for the isotherms of multilayer adsorption

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