Structural analysis of hydrothermal char and its models by density functional theory simulation of vibrational spectroscopy

Brown, Avery B.; McKeogh, Brendan James; Tompsett, Geoffrey A.; Lewis, R.; Deskins, N. Aaron; Timko, Michaël T.

doi:10.1016/j.carbon.2017.09.051

Cited by 42 publications

(36 citation statements)

References 59 publications

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“…The spectra of the heat-treated samples showed an obvious D peak because of the further aromatization during the heat treatment and increase of the ordering. 41 The D and G bands of the MHTCL-modied CFs were similar to those of the by-product CSs and had the same peak positions as previously reported hydrothermal CSs; [42][43][44][45] the Raman spectra differed greatly from those of the CFs. It was veried that the surfaces of the hydrothermal treated CFs were completely covered by the MHTCL, a highly disordered amorphous carbon layer.…”

Section: Sem Analysis Of Mhtcl-modied Cfssupporting

confidence: 74%

A multiscale hydrothermal carbon layer modified carbon fiber for composite fabrication

Chen

Wang

et al. 2018

RSC Adv.

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A novel multiscale hydrothermal carbon layer (MHTCL) for carbon fiber (CF) surface modification was developed. The MHTCL is a multiscale high-disorder amorphous carbon coating with a colored appearance, abundant functional groups, multiscale roughness, a large specific surface area, a high surface energy, and good wetting ability. The O/C atom ratios of the MHTCL-modified CF were in the range of 0.17-0.23, and the functional groups were mainly C-O and C]O groups. During the lowconcentration glucose hydrothermal treatment with the carbon fibers (CFs), the glucose generates furan derivative intermediates, which adsorb on the surface of the CFs and carbonize continuously, finally forming the MHTCL on the CFs. The fracture and rupture of the MHTCL during the forming process produce new nucleation centers on the CF surface, which result in abundant multiscale irregular particles. The MHTCL is a facile method for the modification of CFs. The fabrication of the CF composites demonstrated that the MHTCL obviously increases the interlaminar shear strength of the CF/ polyimide composite and the interfacial interaction of the CF and polyetheretherketone.

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Section: Sem Analysis Of Mhtcl-modied Cfssupporting

confidence: 74%

A multiscale hydrothermal carbon layer modified carbon fiber for composite fabrication

Chen

Wang

et al. 2018

RSC Adv.

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“…Recent work by Brown et al [61] reconciled several disparate models proposed for the structure of hydrochar synthesized from glucose. Previous models inferred from infrared spectroscopy and Raman microscopy [62,64] indicated that hydrochar structures resembled activated carbon and consisted of fused aromatic cores, comprised of many aromatic rings and with OFGs present primarily as side chains.…”

Section: Introductionmentioning

confidence: 96%

“…Density Functional Theory (DFT) is an especially valuable tool for studying the geometry and energetics of sorbate binding to the active site, provided that molecular structures are known that can be used as targets of rational design. Unfortunately, the structural models of hydrochar have only recently converged [61][62][63], making attempts at molecular level design or computational modeling of sorbate-sorbent binding difficult until now.…”

Section: Introductionmentioning

confidence: 99%

Experimental and Computational Evaluation of Heavy Metal Cation Adsorption for Molecular Design of Hydrothermal Char

et al. 2020

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A model hydrochar was synthesized from glucose at 180 °C and its Cu(II) sorption capacity was studied experimentally and computationally as an example of molecular-level adsorbent design. The sorption capacity of the glucose hydrochar was less than detection limits (3 mg g−1) and increased significantly with simple alkali treatments with hydroxide and carbonate salts of K and Na. Sorption capacity depended on the salt used for alkali treatment, with hydroxides leading to greater improvement than carbonates and K+ more than Na+. Subsequent zeta potential and infrared spectroscopy analysis implicated the importance of electrostatic interactions in Cu(II) sorption to the hydrochar surface. Computational modeling using Density Functional Theory (DFT) rationalized the binding as electrostatic interactions with carboxylate groups; similarly, DFT calculations were consistent with the finding that K+ was more effective than Na+ at activating the hydrochar. Based on this finding, custom-synthesized hydrochars were synthesized from glucose-acrylic acid and glucose-vinyl sulfonic acid precursors, with subsequent improvements in Cu(II) adsorption capacity. The performance of these hydrochars was compared with ion exchange resins, with the finding that Cu(II)-binding site stoichiometry is superior in the hydrochars compared with the resins, offering potential for future improvements in hydrochar design.

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“…[22] In fact, some specific aromatic segments (rather than graphitic layers) can generate pronounced signals in both bands. [23] Accordingly, a recent review has concluded that "reliable characterization of the structural CD properties may indeed be a challenge." [11] Nuclear magnetic resonance (NMR) is ideally suited to comprehensively characterize the chemical composition of carbon dots, based on predictable chemical shifts of resonances due to the chemical bonding environment.…”

Section: Introductionmentioning

confidence: 99%

A molecular fluorophore in citric acid/ethylenediamine carbon dots identified and quantified by multinuclear solid‐state nuclear magnetic resonance

Duan

Zhi

Coburn

et al. 2020

Magnetic Reson in Chemistry

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The composition of fluorescent polymer nanoparticles, commonly referred to as carbon dots, synthesized by microwave-assisted reaction of citric acid and ethylenediamine was investigated by 13 C, 13 C{ 1 H}, 1 H─ 13 C, 13 C{ 14 N}, and 15 N solid-state nuclear magnetic resonance (NMR) experiments. 13 C NMR with spectral editing provided no evidence for significant condensed aromatic or diamondoid carbon phases. 15 N NMR showed that the nanoparticle matrix has been polymerized by amide and some imide formation. Five small, resolved 13 C NMR peaks, including an unusual ═CH signal at 84 ppm (1 H chemical shift of 5.8 ppm) and ═CN 2 at 155 ppm, and two distinctive 15 N NMR resonances near 80 and 160 ppm proved the presence of 5-oxo-1,-2,3,5-tetrahydroimidazo[1,2-a]pyridine-7-carboxylic acid (IPCA) or its derivatives. This molecular fluorophore with conjugated double bonds, formed by a double cyclization reaction of citric acid and ethylenediamine as first shown by Y. Song, B. Yang, and coworkers in 2015, accounts for the fluorescence of the carbon dots. Cross-peaks in a 1 H─ 13 C HETCOR spectrum with brief 1 H spin diffusion proved that IPCA is finely dispersed in the polyamide matrix. From quantitative 13 C and 15 N NMR spectra, a high concentration (18 ± 2 wt %) of IPCA in the carbon dots was determined. A pronounced gradient in 13 C chemical-shift perturbations and peak widths, with the broadest lines near the COO group of IPCA, indicated at least partial transformation of the carboxylic acid of IPCA by amide or ester formation.

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Structural analysis of hydrothermal char and its models by density functional theory simulation of vibrational spectroscopy

Cited by 42 publications

References 59 publications

A multiscale hydrothermal carbon layer modified carbon fiber for composite fabrication

A multiscale hydrothermal carbon layer modified carbon fiber for composite fabrication

Experimental and Computational Evaluation of Heavy Metal Cation Adsorption for Molecular Design of Hydrothermal Char

A molecular fluorophore in citric acid/ethylenediamine carbon dots identified and quantified by multinuclear solid‐state nuclear magnetic resonance

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