The design and preparation of new carbon materials (CMs) has long been of interest in the field of materials science. Various novel nanostructured CMs with unique structure and morphology usually exhibit a variety of potential applications owing to their outstanding chemical and physical properties.¹⁻³

Recently, CMs were synthesized through the chemical reactions between calcium carbide (CaC₂) and halogenated hydrocarbons or chlorine gas, which demonstrated promising applications for energy storage like supercapacitors.⁴ The as-prepared porous CMs with low degree of graphitization and high specific surface area are somehow different from the highly-graphitic carbon nanospheres prepared by the reaction of CaC₂ with aluminum chloride hexahydrate or copper dichloride hydrate in sealed stainless steel autoclaves.^5,6 The onion-like carbon nanospheres exhibited good cycling performance as anode materials for lithium-ion batteries (LIBs), delivering a high reversible capacity of 391 mAh/g after 60 cycles at a current density of 37.2 mA/g.⁶

In this work, we report, for the first time, a new one-step approach to prepare CMs by selective thermo-chemical etching the calcium from CaC₂ by sulfur at 550 ^oC. By the comprehensive analysis on structure and morphology by X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), N₂ adsorption−desorption isotherm analysis, scanning electron microscopy (SEM) and transmission electron microscopy (TEM), the prepared CMs reveal a mesoporous structure with high graphitization degree and a specific surface area of 159.5 m²/g. Most of the carbon product displays micron-scale mesoporous frameworks (4–20 um) with distinct layered structure, and the others are the agglomerates of highly-graphitic carbon nanosheets with thickness about 10 nm and lateral size of 1–10 μm (Figure 1a). When tested as anode materials for LIBs, the as-prepared CMs exhibit an excellent cycling performance and rate capabilities, delivering a high reversible capacity of 561.3 mAh/g at 0.1C (1C = 372 mA/g) after 120 cycles (Figure 1b), thus demonstrating intensive potential in electrochemical energy storage. The present study provides a perspective approach to fabricate CMs by the simple, cost-effective, and efficient synthetic route using CaC₂ and sulfur as reactants.

References:

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