The X-ray, Raman and TEM Signatures of Cellulose-Derived Carbons Explained

Mubari, Petros Kasaira; Beguerie, Théotime; Monthioux, Marc; Weiss-Hortala, Elsa; Nzihou, Ange; Puech, Pascal

doi:10.3390/c8010004

Cited by 21 publications

(13 citation statements)

References 51 publications

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“…With the benefit of hindsight, both interdigitated fringes and screws are present in the literature, albeit at lower resolution. For example, TEM by Oberlin 1 and others [5][6][7] show textures and general features matching our observations. Screws are a well known defect in graphite and can be observed on the surface of graphite using optical microscopy, electron microscopy and atomic force microscopy 8,9 .…”

Section: Main Textsupporting

confidence: 89%

Graphite forms via annihilation of screw dislocations

Martin¹,

Fogg²,

J.³

et al. 2022

Preprint

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Graphite is the thermodynamically stable form of carbon, and yet is remarkably difficult to synthesise. A key step in graphite formation is the removal of defects at high temperature (>2300 • C) that allow graphenic fragments to rearrange into ordered crystallites 1 . We find the critical defect controlling graphitisation is a screw dislocation that winds through the layers like a spiral staircase, inhibiting lateral growth of the graphenic crystallites (L a ) and preventing AB stacking of Bernal graphite. High-resolution transmission electron microscopy (HRTEM) identifies screws as interdigitated fringes with narrow focal depth in graphitising polyvinyl chloride (PVC). Molecular dynamics simulations of parallel graphenic fragments confirm that screws spontaneously form during heating, with higher annealing temperature driving screw annihilation and crystallite growth. The time evolution of graphitisation is tracked via X-ray diffraction (XRD), showing the growth of L a and reduction of the interlayer spacing consistent with molecular dynamics of screw annihilation. This mechanistic insight raises opportunities to lower the barrier for graphitisation as well as broadening the range of carbonaceous materials that can turn into graphite, thereby lowering the cost of synthetic graphite used in lithium-ion batteries, carbon fibre, and electrodes for smelting.

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Section: Main Textsupporting

confidence: 89%

Graphite forms via annihilation of screw dislocations

Martin¹,

Fogg²,

J.³

et al. 2022

Preprint

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“…5 a) showed highly disorganized graphene fringes, grouped into small graphenic structures long of few nanometers with a poor stacking (< 4 graphene fringes). The graphene fringes were randomly oriented and highly curved, highlighting a weak structuration typical of hard carbons 78 . The strong curvature and short length (implying lot of edges) of the graphene fringes may explain the significant shift of the Raman D band of the non-impregnated cellulose biochar sample from the D band position of graphite, as well as the broad and asymmetric 10 and 11 bands in the XRD spectra.…”

Section: Resultsmentioning

confidence: 99%

Calcium as an innovative and effective catalyst for the synthesis of graphene-like materials from cellulose

Beguerie

Weiss-Hortala

Nzihou

2022

Sci Rep

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Pyrolysis of lignocellulosic biomass (hard carbon) produces poorly graphitic biochar. In this study, nano-structured biochars were produced from microcrystalline cellulose using calcium as a non-conventional catalyst. Calcium is abundant, environmental-friendly and widely accessible. Graphitization of calcium-impregnated cellulose was carried out at 1800 °C, a temperature below 2000 °C where the graphitization usually occurs. XRD, Raman spectroscopy, high-resolution TEM together with the in-house numerical tool developed enable the quantification of the graphene fringes in the biochars. The non-impregnated cellulose biochar was composed of short and poorly stacked graphene fringes. The impregnation with 2 wt.% of calcium led to the conversion of the initial structure into a well-organized and less defective graphene-like one. The graphene-like structures obtained were composed of tens of stacked graphene fringes with a crystallite size up to 20 nm and an average interlayer spacing equal to 0.345 nm, close to the reference value of standard hexagonal graphite (0.3354 nm). The increase of the calcium concentration did not significantly improve the crystallite sizes of the graphene-like materials but rather drastically improved their rate. Our results propose a mechanism and provide new insights on the synthesis of graphene-like materials from bio-feedstocks using calcium where the literature is focused on transition metals such as iron and nickel among others. The decrease of the graphitization temperature below 2000 °C should lower the production cost as well as the environmental impact of the thermal graphene-like materials synthesis using biomass. This finding should stimulate further research in the field and broaden the application perspectives.

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“…Curve fitting was performed using the Pick Analyzer tool in OriginPro software. The resulting A D1 / A G and A D3 / A G area ratios, which are commonly used to characterize the degree of disorder of biomass chars, − are also listed in Table . From the values of both area ratios, it can be deduced that the higher the impregnation ratio at a given temperature, the higher the degree of disorder.…”

Section: Resultsmentioning

confidence: 99%

Waste Hemp Hurd as a Sustainable Precursor for Affordable and High-Rate Hard Carbon-Based Anodes in Sodium-Ion Batteries

et al. 2023

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The present study reports the promising potential of waste hemp-hurd-derived carbons as anodes in sodium-ion batteries (SIBs). Carbons were produced through an easily scalable process consisting of pyrolysis of raw biomass at 500 °C followed by mild chemical activation of the resulting char through wet impregnation with K2CO3 and subsequent heating of the solid phase (after filtration and drying) up to 700 or 800 °C under nitrogen. The best electrochemical performance was observed for the hard carbon activated at a char-K2CO3 mass ratio of 1:4 and heated up to 800 °C, which exhibited an excellent initial coulombic efficiency (73%) and achieved reversible charge capacities of 267 and 79 mAh g–1 at 0.03 and 1 A g–1, respectively. This material also exhibited an impressive cyclic stability and rate capability, with a capacity retention of 96% after 300 cycles at a current density of 2 A g–1. This more than satisfactory performance could be related to the textural and structural features of the hard carbon, which include moderate interconnected microporosity (with pore sizes below 1 nm), an appropriate concentration of defects in the carbon structure, relatively large interplanar distances, and a certain number of closed pores.

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The X-ray, Raman and TEM Signatures of Cellulose-Derived Carbons Explained

Cited by 21 publications

References 51 publications

Graphite forms via annihilation of screw dislocations

Graphite forms via annihilation of screw dislocations

Calcium as an innovative and effective catalyst for the synthesis of graphene-like materials from cellulose

Waste Hemp Hurd as a Sustainable Precursor for Affordable and High-Rate Hard Carbon-Based Anodes in Sodium-Ion Batteries

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