Abstract The chemical exfoliation of graphite in liquids is the choice method to produce few-layer graphenes with versatility and scalability. While physical mechanisms have been described, the understanding of the graphene-medium interactions at the molecular level is still a challenge. Here, a systematic experimental and theoretical investigation of factors that control the chemical exfoliation of graphite into graphene was performed using 1-cyclohexyl-2-pyrrolidone (CHP)/water mixtures as model systems. The “molecular wedge” structure of CHP and the reduction of graphene-CHP interfacial energy are critical factors in the exfoliation of graphite, but they are not sufficient for the stabilization of the isolated graphene sheets. We propose that such stabilization occurs by steric forces with the formation of a sandwich-like structure on the surface of graphene with two layers of water molecules interleaved with a monolayer of CHP, and by electrostatic forces resulting from the hybrid surface polarization due to the CHP/H2O-graphene interaction. This stabilization is hampered in CHP/H2O mixtures containing above 10 wt% CHP due to the formation of CHP–CHP aggregates.

中文翻译：

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“在 N-环己基吡咯烷酮 + 水混合物中生产少层石墨烯的分子见解”

摘要 石墨在液体中的化学剥离是制备具有多功能性和可扩展性的少层石墨烯的选择方法。虽然已经描述了物理机制，但在分子水平上理解石墨烯-介质相互作用仍然是一个挑战。在这里，使用 1-环己基-2-吡咯烷酮 (CHP)/水混合物作为模型系统，对控制石墨化学剥离成石墨烯的因素进行了系统的实验和理论研究。CHP 的“分子楔”结构和石墨烯-CHP 界面能的降低是石墨剥离的关键因素，但它们不足以稳定孤立的石墨烯片。我们提出这种稳定是通过空间力发生的，在石墨烯表面形成夹心状结构，两层水分子与单层 CHP 交错，以及由 CHP 引起的混合表面极化产生的静电力/H2O-石墨烯相互作用。由于 CHP-CHP 聚集体的形成，这种稳定性在含有超过 10 wt% CHP 的 CHP/H2O 混合物中受到阻碍。