Atomic scale investigations of catalyst and catalytic graphitization in a silicon and titanium doped graphite

Lin, Qingyun; Feng, Zhihai; Guo, Quangui; Hu, Zhiqiang; He, L. L.; Ye, Hengqiang

doi:10.1016/j.carbon.2015.03.001

Cited by 37 publications

(19 citation statements)

References 32 publications

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“…The third is the dissolution-precipitation sequence that occurs by the carbide formation. Many researchers reported that titanium reacts readily with carbon to form carbide following the third mechanism [7,34].…”

Section: Catalytic Mechanism Of Rare-earth Elementsmentioning

confidence: 99%

Catalytic effect of praseodymium oxide additive on the microstructure and electrical property of graphite anode

Wang

Qiao

et al. 2015

Carbon

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Based on the revealed interactions (dissociation energy) between several typical metals (transition and rare-earth elements) and carbon atoms through the DFT quantum mechanics method, Pr can be predicted to possibly be a new potential catalyst. Indeed, Praseodymium oxide (Pr 6 O 11 ) was insightfully found to catalyze the graphitization more efficiently than the other selected additives. The effects of Pr 6 O 11 catalyst on the microstructure of the graphite anode were investigated by XRD, Raman spectroscopy, SEM, and TEM. The results indicate that Pr 6 O 11 addition remarkably improves the formation of crystallites, thereby largely enhancing the electrical property of graphite anode. The graphite anode with a low electrical resistivity of 5.0 μΩ·m was successfully available by adding 3 wt. % Pr 6 O 11 at 2800 °C. Finally, the catalytic graphitization mechanism of rare-earth element was proposed based on the experimental results.

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Section: Catalytic Mechanism Of Rare-earth Elementsmentioning

confidence: 99%

Catalytic effect of praseodymium oxide additive on the microstructure and electrical property of graphite anode

Wang

Qiao

et al. 2015

Carbon

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“…GEINs are the main product in the solid residues of catalytically graphitized biomass when iron is used as the transition metal [ 15 ]. Two possible mechanisms have been proposed to explain the formation of ordered carbon materials from solid carbon resources over transition metal catalysts: the dissolution–precipitation theory [ 31 , 32 ] and the metal carbide formation–decomposition process [ 33 , 34 ]. In the dissolution–precipitation theory, the carbon atoms in the disorder carbons diffuse and dissolve into the metal and/or metal carbide with elevated temperature.…”

Section: Resultsmentioning

confidence: 99%

A Study of the Key Factors on Production of Graphene Materials from Fe-Lignin Nanocomposites through a Molecular Cracking and Welding (MCW) Method

2021

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In this work, few-layer graphene materials were produced from Fe-lignin nanocomposites through a molecular cracking and welding (MCW) method. MCW process is a low-cost, scalable technique to fabricate few-layer graphene materials. It involves preparing metal (M)-lignin nanocomposites from kraft lignin and a transition metal catalyst, pretreating the M-lignin composites, and forming of the graphene-encapsulated metal structures by catalytic graphitization the M-lignin composites. Then, these graphene-encapsulated metal structures are opened by the molecule cracking reagents. The graphene shells are peeled off the metal core and simultaneously welded and reconstructed to graphene materials under a selected welding reagent. The critical parameters, including heating temperature, heating time, and particle sizes of the Fe-lignin composites, have been explored to understand the graphene formation mechanism and to obtain the optimized process parameters to improve the yield and selectivity of graphene materials.

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“…The graphitization of amorphous carbon with the aid of transition metal catalysts was discussed in several studies. − ,,, There are mainly two kinds of mechanisms: one is the dissolution of carbon into molten metal, and then the metal and graphite crystals precipitate from the saturation; another is the formation of an intermediate productmetal carbide, which then decomposes and recrystallizes to the metal and graphite crystals. , Ti and Fe were proved to follow different paths to affect carbon materials owing to their different interactions with carbon. Previously, Ti was confirmed to catalyze the graphitization of natural graphite flake followed by both catalytic mechanisms, whereas Fe catalyzed such graphitization followed just by the former mechanism. , On the basis of these mechanisms, the catalytic effects of light rare earth elements (La, Ce, and Pr) were investigated along with those of Ti and Fe for comparison.…”

Section: Resultsmentioning

confidence: 99%

“…In a narrow sense, high temperature becomes the limitation of investigation with in situ techniques. Recently, Lin et al studied the catalytic graphitization process of graphite blocks that were heat-treated at 2700 °C with Ti as the catalyst, whose raw materials were natural graphite flake and mesophase pitch . Through TEM images and selected-area electron diffraction (SAED) analysis, they confirmed that silicon carbide exhibited the catalytic effect with carbide formation–decomposition process, whereas both carbide formation–decomposition and dissolution–precipitation were involved in the formation process of graphite doped with Ti.…”

Section: Introductionmentioning

confidence: 99%

Catalytic Graphitization of Coal-Based Carbon Materials with Light Rare Earth Elements

Wang

Qiao

et al. 2016

Langmuir

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The catalytic graphitization mechanism of coal-based carbon materials with light rare earth elements was investigated using X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, selected-area electron diffraction, and high-resolution transmission electron microscopy. The interface between light rare earth elements and carbon materials was carefully observed, and two routes of rare earth elements catalyzing the carbon materials were found: dissolution-precipitation and carbide formation-decomposition. These two simultaneous processes certainly accelerate the catalytic graphitization of carbon materials, and light rare earth elements exert significant influence on the microstructure and thermal conductivity of graphite. Moreover, by virtue of praseodymium (Pr), it was found that a highly crystallographic orientation of graphite was induced and formed, which was reasonably attributed to the similar arrangements of the planes perpendicular to (001) in both graphite and Pr crystals. The interface between Pr and carbon was found to be an important factor for the orientation of graphite structure.

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Atomic scale investigations of catalyst and catalytic graphitization in a silicon and titanium doped graphite

Cited by 37 publications

References 32 publications

Catalytic effect of praseodymium oxide additive on the microstructure and electrical property of graphite anode

Catalytic effect of praseodymium oxide additive on the microstructure and electrical property of graphite anode

A Study of the Key Factors on Production of Graphene Materials from Fe-Lignin Nanocomposites through a Molecular Cracking and Welding (MCW) Method

Catalytic Graphitization of Coal-Based Carbon Materials with Light Rare Earth Elements

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