Structure evolution mechanism of highly ordered graphite during carbonization of cellulose nanocrystals

Eom, Youngho; Son, Sung Min; Kim, Yea Eun; Lee, Jung-Eun; Hwang, Sang-Ha; Chae, Han Gi

doi:10.1016/j.carbon.2019.05.007

Cited by 76 publications

(42 citation statements)

References 61 publications

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“…The intensities of both the G and D1 peaks increase with carbonization temperature, which suggests a transformation towards a more graphitic carbon structure, consistent with the XPS results. But the strong D1 peak also indicates that some defects (such as the edges of the graphite 21 , 34 ) still exist in the carbon matrix. Moreover, the slightly reduced ratio of I D1 / I G and the reduced intensity of the D2 peak (disordered graphitic lattice) indicate that the formed graphitic carbon tends to be more ordered at higher carbonization temperature.…”

Section: Resultsmentioning

confidence: 99%

“…Cellulose, an abundant renewable and low-cost biomaterial, containing only C, H, and O atoms, has recently exhibited particularly promising potential as an effective precursor for CMS membranes with high gas selectivities 19 , 20 . Moreover, microcrystalline cellulose (MCC), which has high crystallinity, is advantageous for forming CMS membranes with a more ordered graphitic structure 21 , and may thus provide high selectivity by molecular sieving. In addition, it was found that the cellulose-derived CMS membrane has shown stable performance for O 2 /N 2 separation under ~80% relative humidity because of its high hydrophilicity that allows water vapor to permeate the membrane easily 20 .…”

Section: Introductionmentioning

confidence: 99%

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Carbon hollow fiber membranes for a molecular sieve with precise-cutoff ultramicropores for superior hydrogen separation

et al. 2021

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Carbon molecular sieve (CMS) membranes with rigid and uniform pore structures are ideal candidates for high temperature- and pressure-demanded separations, such as hydrogen purification from the steam methane reforming process. Here, we report a facile and scalable method for the fabrication of cellulose-based asymmetric carbon hollow fiber membranes (CHFMs) with ultramicropores of 3–4 Å for superior H2 separation. The membrane fabrication process does not require complex pretreatments to avoid pore collapse before the carbonization of cellulose precursors. A H2/CO2 selectivity of 83.9 at 130 °C (H2/N2 selectivity of >800, H2/CH4 selectivity of >5700) demonstrates that the membrane provides a precise cutoff to discriminate between small gas molecules (H2) and larger gas molecules. In addition, the membrane exhibits superior mixed gas separation performances combined with water vapor- and high pressure-resistant stability. The present approach for the fabrication of high-performance CMS membranes derived from cellulose precursors opens a new avenue for H2-related separations.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Carbon hollow fiber membranes for a molecular sieve with precise-cutoff ultramicropores for superior hydrogen separation

et al. 2021

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“…Chou et al [33] reported a multi-step protocol for the conversion of commercial microcrystalline cellulose into carbonized fibers on nanoscale using the freeze drying technique. Recently, Eom et al [34] described the graphitization process of CNCs from 1000 to 2500 °C using spray pyrolysis methodology to obtain fiber structures. Moreover, rounded carbon particles have been successfully used for water purification and environmental remediation [35,36], composites production [37,38] and energy storage [39].…”

Section: Nano-and Microstructured Carbon Materials Have Gainedmentioning

confidence: 99%

“…11a). At higher temperatures, these domains become bigger and ordered with layered graphitic structures [34]. According to Ferrari et al [57], the transition phase from amorphous to nanocrystalline graphite carbon could be monitored through the shift of I G peak position from low to higher Raman shift.…”

Section: Conductivity Measurements Of Carbonized Cncsmentioning

confidence: 99%

Shape tunability of carbonized cellulose nanocrystals

et al. 2019

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Bioderived scaffolds are largely used as template for the synthesis of drugs and materials. Among biomass sources, cellulose has been used as platform for numerous conversions and applications. In this study, we report the use of crystalline microstructured cellulose as feedstock for microstructured carbon production. Different morphologies were produced according to pyrolytic conditions ranging from sphere, needle and carbon-on-carbon-decorated surfaces. All the materials were characterized using spectroscopic techniques (i.e., Raman, FTIR), FESEM and thermogravimetric analysis. Hypothetical reaction pathways were proposed for describing materials shape and properties. In particular, for cellulose nanocrystals, the thermal treatments induced noteworthy electrical properties that could be applied for the production of conductive composites.

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“…Due to inorganic content and high oxygen content, biochar could be classified into non-graphitizable carbon according to Franklin definition but by increasing pyrolysis or carbonization temperature, biochar undergoes a turbostratic rearrangement with massive formation of sp 2 cluster. Those domains are composed by randomly distributed disordered and nanographitic domains that can reached up to 80 nm in size and eventually evolve to graphite-like materials for temperature above 2000 °C as in the case of carbonization of cellulose nanocrystals [ 9 ].…”

Section: Introductionmentioning

confidence: 99%

Introducing the Novel Mixed Gaussian-Lorentzian Lineshape in the Analysis of the Raman Signal of Biochar

et al. 2020

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In this research, an innovative procedure is proposed to elaborate Raman spectra obtained from nanostructured and disordered solids. As a challenging case study, biochar, a bio-derived carbon based material, was selected. The complex structure of biochar (i.e., channeled surface, inorganic content) represents a serious challenge for Raman characterization. As widely reported, the Raman spectra are closely linked to thermal treatments of carbon material. The individual contributions to the Raman spectra are difficult to identify due to the numerous peaks that contribute to the spectra. To tackle this problem, we propose a brand new approach based on the introduction, on sound theoretical grounds, of a mixed Gaussian-–Lorentzian lineshape. As per the experimental part, biochar samples were carbonized in an inert atmosphere at various temperatures and their respective spectra were successfully decomposed using the new lineshape. The evolution of the structure with carbonization temperature was investigated by Raman and XRD analysis. The results of the two techniques fairly well agree. Compared to other approaches commonly reported in the literature this method (i) gives a sounder basis to the lineshape used in disordered materials, and (ii) appears to reduce the number of components, leading to an easier understanding of their origin.

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Structure evolution mechanism of highly ordered graphite during carbonization of cellulose nanocrystals

Cited by 76 publications

References 61 publications

Carbon hollow fiber membranes for a molecular sieve with precise-cutoff ultramicropores for superior hydrogen separation

Carbon hollow fiber membranes for a molecular sieve with precise-cutoff ultramicropores for superior hydrogen separation

Shape tunability of carbonized cellulose nanocrystals

Introducing the Novel Mixed Gaussian-Lorentzian Lineshape in the Analysis of the Raman Signal of Biochar

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