Elsevier

Carbon

Volume 161, May 2020, Pages 277-286
Carbon

Millimeter-scale laminar graphene matrix by organic molecule confinement reaction

https://doi.org/10.1016/j.carbon.2020.01.075Get rights and content

Abstract

Application of the graphene-based composites in practice was hampered due to the lack of the controllable synthesis strategy. To solve the problem, we envisaged the organic nanodroplets as a nano-reaction environment to obtain the organic nanoframes by photo-polymerization, then to directly graphitize for the graphene-based materials. In such strategy, two-dimensional laminar matrix of graphene nanosheets (2DLMG) was obtained with millimeter-scale surface, which rendered the matrix high electron conductivity. Thanks to the confinement effect of the nanodroplets, the composited materials were homogeneously dispersed in the organic nanoframes. Then, the organic nanoframes converted directly to 2DLMG-based composites after calcination. In this paper, the transformation from organic nanoframes to 2DLMG has been revealed in detail by comprehensive analyses from SEM, XRD and XPS. To demonstrate the versatility of 2DLMG, the superiority in lithium ion battery has been indicated by the high specific capacity (565 mA h g−1), high cycling performance after 500 cycles and the 100% retention capacity in rate measurement. For the synthesis of the composites, Sn nanoparticles and γ-Fe2O3 nanoparticles were distributed in 2DLMG without the aggregation with high loading. The proposed organic molecule confinement reaction strategy was expected to point out a promising direction for the preparation of graphene-based materials.

Introduction

Graphene have been prevalent over the past two decades due to the surreal properties of the graphene such as high mechanic strength, electronic conductivity [1]. A plant of strategies have been developed to produce a single layer graphene with high quality and large area, such as mechanical exfoliation, reduction of the graphene oxide, synthesis on silicon carbide (SiC), liquid-phase exfoliation, chemical vapor deposition (CVD), bottom-up synthesis by organic molecule or a few layer graphene, such as Hummers’ method [2].

For the attainment of graphenes’ application in practice, especially in energy storage or catalysis, the synthesis of the graphene-based composites is crucial. A single layer graphene was not inherently suitable for the composites due to the trend of cluster formation by repulsive force between the composited materials cations [[3], [4], [5]]. Reversely, a few-layers graphene-based composites supported a possibility to overwhelm the embarrassment.

Thus, the graphene-based composites were generally obtained from the reduction of graphite oxide (GO) with aid by hummers’ method in practice [6,7]. In this strategy, the single atomic layer of sp2 carbon is exfoliated and dispersed in water by the introduction of intercalants between layers of the graphite, such as epoxides, alcohols, ketone carbonyls, and carboxylic groups [8]. The intercalants not only expend the d-spacing of layers but also improve the interaction between the surface of graphene and the composited materials at same time. Then, the composited materials, usually metallic salts, were added in to the suspension to obtain metal/metal oxide nanoparticles on the surface of graphene by hydrothermal reaction or calcination. Finally, the composites require to be reduced to render the properties of graphene again. The procedure not only involve the use of hazard solvent for intercalants viz. H2SO4/KMnO4, carboxylic acid, and formic acid and high energy procedure for exfoliation [9,10], but also is labor-intensive and inefficient [11]. In addition, based on such top-down strategy, the local position of the intercalants on the surface of the GO can’t be controlled. When the graphene combines the other materials, it results in a heterogeneous growth and aggregation of composite materials on the GO surface. It is fatal for the performance of materials in applications.

Therefore, developing a controllable synthesized strategy for the graphene-based materials is crucial for the application of the graphene-based materials. The bottom-up strategy starting from organic molecular precursors have been reported for the production of the graphene. The thermolysis of the polymer starting from well-defined carbon-rich precursors is so simple that more favorable for application. Such strategy supports the exact controllability of the molecules in carbon backbone and homogeneous distribution of the composited materials on the surface of the graphene. However, It was well known that such bottom-up method generally involved the expensive and complex hardware to create the single-atom layer [12,13] such as the ultra-vacuum equipment. Moreover, to easily obtain the hexagonal lattice structure, the aromatic molecular precursor is essential [[14], [15], [16]]. Thus, the conventional bottom-up strategy results in the high cost and non-friendly environment at same time. These limit the superiority exhibition of such methods for the production of the graphene-based materials.

To end the circumstances, we proposed a novel bottom-up strategy to synthesize a 2D laminar matrix of graphene nanosheets (2DLMG) in this context. To create a monolayer molecular layer and avoid the use of special and expensive equipment during synthesis. The organic nanodroplets obtained by the spontaneous nano-emulsification sourcing from biomass (Labrafac WL 1349, An oily vehicle in pharmaceutics [17]) was designed as a nano reaction environment to photo-polymerize acrylic monomer (Tripropylene Glycol Diacrylate, TPGDA) for forming an organic nanoframes, which does not cause toxicity to internal organs [18]. Finally, the organic nanoframes were transformed to be the 2DLMG thanks to the confinement effect of nanodroplets during calcination. The synthesized 2DLMG have a millimeter-scale surface, which is important to obtain the high electronic conductivity and application in electronic device. On the other hand, the composited materials can be simply mixed in the nanoemulsion before calcination for the composites. Due to the confinement of nanodroplets, the metal or metal oxide nanoparticles should be homogeneously distributed in matrix. Thus, the proposed strategy supported an eco-friendly, cost effective, controllable and easily functionalized 2DLMG. It is expected the proposed organic molecule confinement reaction strategy will spread the 2DLMG to graphene-based composite materials, and promote their applications in practice.

Section snippets

Materials

Labrafac® WL 1349 (Gattefossé S.A., Saint-Priest, France), Medium chain triglyceride, was used in the preparation of nano-droplets, which is a mixture of capric and caprylic acid triglycerides as a model of parenteral-grade oil. Nonionic surfactant Kolliphor ELP® (BASF, Ludwigshafen, Germany) is a polyoxyethylated- 35 castor oil, HLB = 12–14, used as a surfactant. Tri(propylene glycol) diacrylate (TPGDA), 1-Hydroxycyclohexyl phenyl ketone (HCPK, as photoinitiator, 99% purity), SnCl4·5H2O,

Results and discussion

2D Laminar Matrix of Graphene nanosheets (2DLMG) (Fig. 1e), a graphene-based materials, have been synthesized by a completely novel bottom-up strategy. Distinguished from conventional bottom-up methods, it does not involve the use of hazard organic molecule (Benzenoids), expensive equipment and rigorous reaction environment. In proposed strategy, the nanodroplets provide the nano-reaction environment to generate an organic nanoframes (Fig. 1b) by photo-polymerization. Then, such organic

Conclusion

The novel graphene-based 2DLMG have been prepared successfully by an organic molecule confinement reaction strategy. Distinguished from the use of special aromatic molecules and expensive devices in rigorous condition during the conventional bottom-up method, the route adopts the non-toxicity biomass to create nanodroplets as the nano-reaction environment for the formation of organic nanoframes by the UV polymerization of acrylic monomer. Then the organic nanoframes self-assemble to the 3D

CRediT authorship contribution statement

Shukai Ding: Conceptualization, Methodology, Writing - original draft. Wei Cheng: Investigation, Formal analysis. Gaohui Du: Supervision, Writing - review & editing. Qingmei Su: Methodology. Linjuan Guo: Methodology. Xiaojuan Chen: Investigation. Shuai Zhang: Investigation. Lin Shang: Investigation. Xiaodong Hao: Investigation. Bingshe Xu: Writing - review & editing. Christophe A. Serra: Writing - review & editing.

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgments

The authors would like to acknowledge the funding from the National Natural Science Foundation of China (No. 11574273), the Youth Innovation Team of Shaanxi University, Foundation of ShaanXi University of Science and Technology (Grant No. 126021823), Natural Science Foundation of Shaanxi Province China (Grant No. 2018JQ5164), Natural Science Foundation of Educational Department in ShaanXi Province, China (Grant No. 18JK0114).

References (42)

  • D. Zhan et al.

    Electronic structure of graphite oxide and thermally reduced graphite oxide

    Carbon

    (2011)
  • F.S. Alhumaidan et al.

    Changes in asphaltene structure during thermal cracking of residual oils: XRD study

    Fuel

    (2015)
  • P. Lian et al.

    Large reversible capacity of high quality graphene sheets as an anode material for lithium-ion batteries

    Electrochim. Acta

    (2010)
  • R. Raccichini et al.

    The role of graphene for electrochemical energy storage

    Nat. Mater.

    (2015)
  • William S. Hummers et al.

    Preparation of graphitic oxide

    J. Am. Chem. Soc.

    (1957)
  • E. Pollak et al.

    The interaction of Li + with single-layer and few-layer graphene

    Nano Lett.

    (2010)
  • E. Lee et al.

    Li absorption and intercalation in single layer graphene and few layer graphene by first principles

    Nano Lett.

    (2012)
  • X. Wang et al.

    A new high-performance metallic carbon anode material for lithium-ion batteries

    Carbon

    (2018)
  • D.C. Marcano et al.

    Correction to improved synthesis of graphene oxide

    ACS Nano

    (2018)
  • L. Zhi et al.

    A bottom-up approach from molecular nanographenes to unconventional carbon materials

    J. Mater. Chem.

    (2008)
  • J. Cai et al.

    Atomically precise bottom-up fabrication of graphene nanoribbons

    Nature

    (2010)
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