Thermophysical features of carbon nanotubes frameworks formation by spark plasma sintering

Suslova, E. V.; Chernyak, S. A.; Максимов, С. В.; Savilov, S. V.

doi:10.1016/j.carbon.2020.07.026

Cited by 16 publications

(8 citation statements)

References 52 publications

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“…It was previously shown that CNTs could sinter at high temperature and/or pressure of SPS via graphene sheet formation. These graphene sheets link two individual CNTs [ 34 , 37 , 38 ]. Under less severe SPS conditions the improvements in the CNT structure were observed [ 34 , 39 , 40 ].…”

Section: Resultsmentioning

confidence: 99%

“…These graphene sheets link two individual CNTs [ 34 , 37 , 38 ]. Under less severe SPS conditions the improvements in the CNT structure were observed [ 34 , 39 , 40 ]. We believe that SPS conditions selected in our work (1000 °C and 22 MPa) were sufficient for the CNT surface recrystallization and defects «healing».…”

Section: Resultsmentioning

confidence: 99%

“…Previous studies have shown the decrease in the I D 1 /I G ratio with increasing the SPS temperature or pressure in Raman spectra of consolidated CNTs because of the healing of defects during SPS, which improved the perfection of the graphitic structure [ 34 ]. In our case the I D 1 / I G ratio linearly increased with increasing O content under oxidation of sintered CNTs, while the I 2 D 1 / I G ratio showed the opposite trend ( Figure 4 b), which agrees with the previous results [ 46 , 47 ].…”

Section: Resultsmentioning

confidence: 99%

“…CNTs sintered by SPS can be classified as a 3D materials [ 33 , 34 ]. According to the Raman spectroscopy data the structure of carbon layers in CNTs improves under SPS consolidation ( Figure 4 ).…”

Section: Discussionmentioning

confidence: 99%

“…SPS was performed on a Labox-625 (Sinterland, Nagaoka City, Japan) apparatus at 1000–1100 °C for 5 min under the axial pressure of 22–30 MPa in a vacuum of 10 −2 torr as described in [ 26 , 34 ]. Linear shrinkage of the specimen during SPS was continuously monitored.…”

Section: Methodsmentioning

confidence: 99%

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Conversion of Secondary C3-C4 Aliphatic Alcohols on Carbon Nanotubes Consolidated by Spark Plasma Sintering

et al. 2021

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We analyze how the changes in the dimension of carbon nanomaterial (CNM) affect their catalytic conversion of secondary aliphatic alcohols. Carbon nanotubes (CNTs) consolidated by spark plasma sintering (SPS) were inactive in the conversion of secondary C3-C4 aliphatic alcohols because of the «healing» of defects in carbon structure during SPS. Gas-phase treatment of consolidated CNTs with HNO3 vapors led to their surface oxidation without destruction of the bulk structure of pellets. The oxygen content in consolidated CNTs determined by X-ray photoelectron spectroscopy increased from 11.3 to 14.9 at. % with increasing the oxidation time from 3 to 6 h. Despite the decrease in the specific surface area, the oxidized samples showed enhanced catalytic activity in alcohol conversion because of the increased number of oxygen radicals with unpaired electrons, which was established by electron paramagnetic resonance spectroscopy. We conclude that the structure of CNM determines the content and/or ratio of sp2 and sp3-hybridized carbon atoms in the material. The experimental and literature data demonstrated that sp3-hybridized carbon atoms on the surface are probably the preferable site for catalytic conversion of alcohols.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Conversion of Secondary C3-C4 Aliphatic Alcohols on Carbon Nanotubes Consolidated by Spark Plasma Sintering

et al. 2021

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Molybdenum Dioxide Nanoparticles Anchored on Nitrogen‐Doped Carbon Nanotubes as Oxidative Desulfurization Catalysts: Role of Electron Transfer in Activity and Reusability

Zou

Lin

et al. 2021

Adv Funct Materials

153

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Electron transfer between metal-oxides and supports considerably affects the oxidative desulfurization (ODS) performance of catalysts, while this is far from being well understood. Herein, molybdenum dioxide with oxygen vacancies (V O -MoO 2 ) catalysts derived from Mo-based metal-organic frameworks are anchored on electron-rich nitrogen-doped carbon nanotubes (NC) to obtain excellent ODS activity and reusability. Results show that either dibenzothiophene (DBT) or 4,6-dimethyldibenzothiophene (4,6-DMDBT) is removed 100% on the composite catalyst (V O -MoO 2 @NC) within 40 min of reaction when cumene hydroperoxide is chosen as an oxidant. After five cycles of reaction, DBT and 4,6-DMDBT removal still exceeded 99.5 and 95.0%, respectively. Results from density functional theory calculations and characterizations confirm that the strong electron-donating effect of NC on V O -MoO 2 can promote the dispersion of V O -MoO 2 and reduce the bond energy of the MoO bond, leading to exposure of active sites and enrichment of oxygen vacancies (V O ).Furthermore, the strong interfacial electrostatic interaction caused by the electron transfer from NC to V O -MoO 2 can reduce the leaching of active sites of the catalyst. This study provides a versatile strategy of constructing strong electronic interaction between metal-oxide and support via anchoring on NC for the design of high-performance ODS catalysts.

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Embedding Metal–Organic Frameworks for the Design of Flexible Hybrid Supercapacitors by Electrospinning: Synthesis of Highly Graphitized Carbon Nanofibers Containing Metal Oxide Nanoparticles

Zhu²,

et al. 2022

Small Structures

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Electrospun carbonaceous fibers have emerged as promising electrode materials for application in energy storage devices. However, their relatively poor electrical conductivity (due to their amorphous carbon structures) and low capacitive performance lead to poor prospects for their further application. Herein, a universal synthesis of highly graphitized carbon nanofibers, containing various metal oxide nanoparticles (e.g., Fe2O3, NiO), by the pyrolysis of metal–organic framework (MOF)‐embedded electrospun nanofibers, is reported. The resulting carbon nanofibers exhibit large mesopore volumes, contain large quantities of Faradic metal oxide nanoparticles, and are highly graphitized. The fibers also have excellent mechanical flexibility, provide fast ion transfer characteristics, and a large pseudocapacitance combined with excellent electrical conductivity, leading to large specific capacitances. Consequently, asymmetric flexible hybrid supercapacitors assembled from Fe2O3‐embedded highly graphitized carbon nanofibers (FOCNF) and NiO‐embedded highly graphitized carbon nanofibers (NOCNF) exhibit a high energy density of 43.1 Wh kg−1 at a power density of 412.5 W kg−1 and possess excellent flexibility (capacitance retention of 94.4% at 180° bending and 96.2% at 30° twisting) with superior cycling stability. This strategy provides a new MOF‐based approach for the design and synthesis of multifunctional flexible carbonaceous materials and might lead to their further application in flexible energy storage devices.

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Thermophysical features of carbon nanotubes frameworks formation by spark plasma sintering

Cited by 16 publications

References 52 publications

Conversion of Secondary C3-C4 Aliphatic Alcohols on Carbon Nanotubes Consolidated by Spark Plasma Sintering

Conversion of Secondary C3-C4 Aliphatic Alcohols on Carbon Nanotubes Consolidated by Spark Plasma Sintering

Molybdenum Dioxide Nanoparticles Anchored on Nitrogen‐Doped Carbon Nanotubes as Oxidative Desulfurization Catalysts: Role of Electron Transfer in Activity and Reusability

Embedding Metal–Organic Frameworks for the Design of Flexible Hybrid Supercapacitors by Electrospinning: Synthesis of Highly Graphitized Carbon Nanofibers Containing Metal Oxide Nanoparticles

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