Synthesis of graphene quantum dots for their supramolecular polymorphic architectures
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Synthesis of graphene quantum dots for their supramolecular polymorphic architectures Weifeng Chen, Guo Lv, Qiyun Zhou, Jialu Shen, Jie Cao, Xiang Liu (), and Zhongxu Dai () Key Laboratory of Inorganic Nonmetallic Crystalline and Energy Conversion Materials, College of Materials and Chemical Engineering, China Three Gorges University, Yichang 443002, China © Tsinghua University Press and Springer-Verlag GmbH Germany, part of Springer Nature 2020 Received: 9 July 2020 / Revised: 22 October 2020 / Accepted: 9 November 2020
ABSTRACT How to regulate the supramolecular structures in the assembly of graphene quantum dots (GQDs) is still a great challenge to be overcome. Herein, the GQDs of 1–3 layers with high quality are synthesized from the new precursor m-trihydroxybenzene in a green method. More importantly, a strategy for designing the supramolecular structures of GQDs is demonstrated, and the novel supramolecular morphologies of GQDs have been constructed for the first time. Moreover, the supramolecular morphologies of GQDs can be well controlled by regulating the preparation conditions, and the formation mechanism of the branch-like supramolecular structure has been explained by the the diffusion-limited aggregation (DLA) model. This work not only develops a new precoursor to synthesize GQDs, but also opens up an effective route to form the polymorphic supermolecules, thus greatly facilitating their potential applications.
KEYWORDS graphene quantum dots, supermolecule, m-trihydroxybenzene, synthesis, the diffusion-limited aggregation
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Introduction
Graphene quantum dots (GQDs) are attracting the tremendous interest in many science fields, due to their outstanding chemical and physical performances [1–3]. GQDs can be regarded as the small pieces of graphene (less than 100 nm), with a graphene-like structural framework of sp2 hybridized carbon [4–6]. The band gap energy of GQDs can be regulated from 0 to 6 eV by controlling the nanoscale sizes or changing the surface functional groups. Meanwhile, GQDs exibit excellent hydrophilicity, low biotoxicity, and stable photoluminescence (PL) [7–9]. All of these advantages endow GQDs with the better potential applications in sensors, biological fields, optoelectronic and energy devices [10–12]. Moreover, due to the coexistence of the oxygen-containing groups and aromatic structure, there are secondary forces, i.e., π–π, hydrogen bonding, and electrostatic interactions among the GQDs, making them high possible to build blocks for constructing the supramolecular structures [13, 14]. However, the GQDs often have to be chemically modified before self-assembling, which increases the difficulty and complexity of the preparation process [15]. In addtion, the organic solvents are often to be used to regulate the morphologies in the self-assembly of GQDs [16]. Furthermore, it is difficult to achieve the tunable morphologies and controllable supramolecular structures of GQDs, leading to very few researches reported in the literatures [15, 16]. Therefore, how to facilely and eff
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