sp amorphous carbons in view of multianalytical consideration: Normal, expeсted and new

Abstract

The suggested approach "Selected set of samples + selected set of analytical tools" occurred quite efficient when applying to sp 2 amorphous carbons, thus providing a transformation of 'amorphous' representation of the issue, based on particulars, into a 'crystalline' one based on a limited set of fixed commonalities. The slogan first part implies a set of different-origin solid samples. The second part concerns analytical tools, the most suitable to achieve the goal. The parts combining means the application of each tool to the whole set of samples. In the current study, two natural sp 2 amorphous carbons, namely, shungite carbon and antraxolite, as well as two engineered products -carbon blacks CB632 and CB624, all of the four bodies belonging to the elitist highest-carbon-content sp 2 species, were subjected to analytical study by using modern structural and compositional analytical techniques. The approach has allowed disclosing the following steady points that are common to the whole class of this carbon allotrope and that may lay the foundation of consolidate, more 'crystalline' representation of what are sp 2 amorphous carbons:1. sp 2 Amorphous carbons are products of particular chemical reactions related to their basic structural units. Further macroscopic agglomeration of the latter plays a subsidiary role. 2. The units represent framed graphene molecules of 1-2 nm and 1-x*10 (x=1-3) nm in size in the case of natural and engineered products, respectively.3. Framing of graphene molecules, predominantly incomplete with respect to the number of vacant places, concerns only edge atoms and is implemented by the related chemical additives, such as hydrogen, oxygen, nitrogen, sulfur and halogens which are attached to the carbon core via chemical bonding. 4. The molecules small size provides a countable number of newly formed chemical bonds.INS and XPS allow attributing the bonds to chemical compositions restricted by number while QCh ensures reliable support. 5. Temperature and pressure as well as physical state and chemical content of surrounding media are the main factors governing geochemistry and technical chemistry of carbon products. 6. Graphene molecules, laying the foundation of sp 2 amorphous carbons, are strongly radicalized due to which the latter acquire a new facet in the space of their properties, being the largest repository of stable radicals.

Graphene Domain Signature of Raman Spectra of sp2 Amorphous Carbons

“…The unique ability of carbon atoms to form three kinds of the bonds, differing by the electronic configurations of the atom valence electrons, provides the presence of sp 3 and sp 2 crystalline and amorphous allotropes that are strictly different concerning their structure and properties [ 19 ]. In the current study, our attention will be concentrated on sp 2 ACs, which according to recent comparative studies [ 17 , 18 ], form a particular class of solids. As turned out, the general architecture of both natural and synthetic species is common and can be characterized as multilevel fractal one [ 20 , 21 ], albeit differing in details at each level.…”

“…Concluding the analysis of one-phonon D-G spectra, one should focus on the connection of widely used parameter with the real size of graphene domains. The advantage of the current study is the availability of independent data on the size of the studied BSUs obtained previously [ 17 , 18 ] and presented in Table 1 . Based on these data, we come to unexpected results.…”

“…According to studies [17,18,23], BSUs of both natural and synthetic sp 2 ACs present graphene molecules, which are based on a honeycomb fragments, or graphene domains. Obeying the general laws of chemistry of nanosize objects [24], the domains edge atoms are terminated by heteroatoms and/or atomic groups, including hydrogen, oxygen, nitrogen, sulfur, halogens mainly, making heteroatom necklaces.…”

Graphene Oxyhydride Catalysts in View of Spin Radical Chemistry

“…According to multitarget character of the spin chemistry of graphene molecules [53,58], implementation of each chemical formula given above can be achieved by different ways due to which a large number of GOH molecules can be suggested for each amorphics. Thus, first six-(CB632) and twelve-(ShC and AnthX) member sets were proposed for each of them [47]. Schematic presentation of a shungite carbon globe, presented in Fig.…”

“…The role of heteroatoms in the BSU structures is discussed in the light of their influence on the radical properties of the molecules. Calculations were performed in the framework of UHF semi empirical AM1 approach (technical details can be found in [47]). The data, part of which were earlier obtained and discussed [47], are complemented by new ones related not only to graphene oxyhydrides, but also to the latter, additionally decorated with nitrogen and sulfur atoms, under the common name graphene oxynitrothiohydrides.…”