Direct fabrication of few-layer graphene via molten salt-assisted magnesiothermic reduction

Abstract

Graphene materials like turbostratic graphene exhibit remarkable promise for an array of applications, spanning from electronic devices to aerospace technologies. It is essential to develop a fabrication method that is not only economical and efficient, but also environmentally sustainable. In this study, the molten salt-assisted magnesiothermic reduction (MSAMR) method is proposed for the synthesis of few-layer turbostratic graphene. K₂CO₃ serves as both the carbon source and the catalyst for graphitization, facilitating the formation of the graphene structure, while in-situ generated MgO nanoparticles exert confinement and templating effects on the growth of graphene. The molten salts used effectively prevent the aggregation and the Bernal stacking of graphene sheets, ensuring the few-layer and turbostratic structure. The synergistic effects of K₂CO₃, in-situ generated MgO, and molten salts guarantee the formation of few-layer turbostratic graphene at a relatively low temperature, characterized with 4–8 stacking layers, a mesopore-dominated microstructure, and a high degree of graphitization.

Graphical abstract

Keywords

few-layer turbostratic graphene / magnesiothermic reduction / molten salt / potassium carbonate / graphitization / mesopore-dominated microstructure

References

[1] Luong D X, Bets K V, Algozeeb W A, . Gram-scale bottom-up flash graphene synthesis.Nature, 2020, 577(7792): 647–651

[2] Oh M, Nuckolls K P, Wong D, . Evidence for unconventional superconductivity in twisted bilayer graphene.Nature, 2021, 600(7888): 240–245

[3] Yang J, Li M, Fang S, . Water-induced strong isotropic MXene-bridged graphene sheets for electrochemical energy storage.Science, 2024, 383(6684): 771–777

[4] Carrasco D F, Álvarez-Rubiera E, Villar-Rodil S, . Chemically tuning graphene via anodic exfoliation for enhanced performance in aqueous zinc-based electrochemical energy storage applications.Carbon, 2024, 228: 119293

[5] Shen C, Qing F, Li X . The etching effect of oxygen during the cooling process of graphene CVD synthesis.Carbon, 2024, 230: 119654

[6] Xing Z, Wang B, Halsted J K, . Direct fabrication of nanoporous graphene from graphene oxide by adding a gasification agent to a magnesiothermic reaction.Chemical Communications, 2015, 51(10): 1969–1971

[7] Wang J, Xu X, Cheng T, . Dual-coupling-guided epitaxial growth of wafer-scale single-crystal WS₂ monolayer on vicinal a-plane sapphire.Nature Nanotechnology, 2022, 17(1): 33–38

[8] Moreno C, Vilas-Varela M, Kretz B, . Bottom-up synthesis of multifunctional nanoporous graphene.Science, 2018, 360(6385): 199–203

[9] Zhang Q, Yan B, Feng L, . Progress in the use of organic potassium salts for the synthesis of porous carbon nanomaterials: microstructure engineering for advanced supercapacitors.Nanoscale, 2022, 14(23): 8216–8244

[10] Li X J, Wang X J, Hu X S, . Direct conversion of CO₂ to graphene via vapor‒liquid reaction for magnesium matrix composites with structural and functional properties.Journal of Magnesium and Alloys, 2023, 11(4): 1206–1212

[11] Yin H, Chen P, Xu C, . Shock-wave synthesis of multilayer graphene and nitrogen-doped graphene materials from carbonate.Carbon, 2015, 94: 928–935

[12] Zhao J, Guo Y, Li Z, . An approach for synthesizing graphene with calcium carbonate and magnesium.Carbon, 2012, 50(13): 4939–4944

[13] Tang H, Gao P, Liu X, . Bio-derived calcite as a sustainable source for graphene as high-performance electrode material for energy storage.Journal of Materials Chemistry A: Materials for Energy and Sustainability, 2014, 2(38): 15734–15739

[14] Dyjak S, Kiciński W, Norek M, . Hierarchical, nanoporous graphenic carbon materials through an instant, self-sustaining magnesiothermic reduction.Carbon, 2016, 96: 937–946

[15] Fechler N, Fellinger T P, Antonietti M . “Salt templating”: a simple and sustainable pathway toward highly porous functional carbons from ionic liquids.Advanced Materials, 2013, 25(1): 75–79

[16] Fechler N, Zussblatt N P, Rothe R, . Eutectic syntheses of graphitic carbon with high pyrazinic nitrogen content.Advanced Materials, 2016, 28(6): 1287–1294

[17] Du X, Lin Z, Zhang Y, . Microstructural tailoring of porous few-layer graphene-like biochar from kitchen waste hydrolysis residue in molten carbonate medium: structural evolution and conductive additive-free supercapacitor application.Science of the Total Environment, 2023, 871: 162045

[18] Zhu L, Zhu Z, Zhou J, . Kirkendall effect modulated hollow red phosphorus nanospheres for high performance sodium-ion battery anodes.Chemical Communications, 2020, 56(79): 11795–11798

[19] Ye B, Fan C, Han Y, . Synthesis of high-entropy diboride nanopowders via molten salt-mediated magnesiothermic reduction.Journal of the American Ceramic Society, 2020, 103(9): 4738–4741

[20] Fang Z Z, Middlemas S, Guo J, . A new, energy-efficient chemical pathway for extracting Ti metal from Ti minerals.Journal of the American Chemical Society, 2013, 135(49): 18248–18251

[21] Athanasiou M, Samartzis N, Sygellou L, . High-quality laser-assisted biomass-based turbostratic graphene for high-performance supercapacitors.Carbon, 2021, 172: 750–761

[22] Wu Y, Ren N, Wang T, . Experimental study on optimized composition of mixed carbonate salt for sensible heat storage in solar thermal power plant.Solar Energy, 2011, 85(9): 1957–1966

[23] Pang Z Y, Li G S, Xiong X L, . Molten salt synthesis of porous carbon and its application in supercapacitors: a review.Journal of Energy Chemistry, 2021, 61: 622–640

[24] Yan J, Wang Q, Wei T, . Template-assisted low temperature synthesis of functionalized graphene for ultrahigh volumetric performance supercapacitors.ACS Nano, 2014, 8(5): 4720–4729

[25] Jayaramulu K, Dubal D P, Nagar B, . Ultrathin hierarchical porous carbon nanosheets for high-performance supercapacitors and redox electrolyte energy storage.Advanced Materials, 2018, 30(15): 1705789

[26] Ferrari A C, Meyer J C, Scardaci V, . Raman spectrum of graphene and graphene layers.Physical Review Letters, 2006, 97(18): 187401

[27] Roscher S, Hoffmann R, Ambacher O . Determination of the graphene‒graphite ratio of graphene powder by Raman 2D band symmetry analysis.Analytical Methods, 2019, 11(9): 1224–1228

[28] Zhang Y, Fang Z Z, Sun P, . Kinetically enhanced metallothermic redox of TiO₂ by Mg in molten salt.Chemical Engineering Journal, 2017, 327: 169–182

[29] Yaokawa J, Oikawa K, Anzai K . Thermodynamic assessment of the KCl‒K₂CO₃‒NaCl‒Na₂CO₃ system.Calphad, 2007, 31(2): 155–163

[30] Nanaji K, Sarada B V, Varadaraju U V, . A novel approach to synthesize porous graphene sheets by exploring KOH as pore inducing agent as well as a catalyst for supercapacitors with ultra-fast rate capability.Renewable Energy, 2021, 172: 502–513

[31] Hao P, Zhao Z H, Leng Y H, . Graphene-based nitrogen self-doped hierarchical porous carbon aerogels derived from chitosan for high performance supercapacitors.Nano Energy, 2015, 15: 9–23

[32] Xia M, Chen W, Wu J, . The critical role of anions in the porous biochar structure and potassium release during the potassium-assisted pyrolysis process.Green Chemistry, 2021, 23(23): 9589–9599

RIGHTS & PERMISSIONS

Higher Education Press