Carbon nano‐onions with concentric fullerene‐like carbon shells were synthesized by hydrothermal carbonization of citric acids at 180 °C and formed through the intermediates of graphene quantum dots, graphitic nano‐sheets and graphitic hollow polyhedrons. The graphene quantum dots were firstly formed by the dehydration of citric acids and then grew and stacked into graphitic nano‐sheets, which curved into graphitic hollow polyhedrons due to the interface energy. The graphitic hollow polyhedrons eventually transformed into spherical carbon nano‐onions with the lowest interface energy in the hydrothermal solution by disordering and rearrangement of the carbon shell.

中文翻译：

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从柠檬酸水热合成碳纳米洋葱。

通过在180°C下对柠檬酸进行水热碳化来合成具有同心富勒烯状碳壳的碳纳米洋葱，并通过石墨烯量子点，石墨纳米片和石墨空心多面体的中间体形成。石墨烯量子点首先通过柠檬酸的脱水形成，然后生长并堆叠成石墨纳米片，由于界面能而弯曲成石墨空心多面体。石墨中空多面体最终通过碳壳的无序排列和重排，转变成在水热溶液中具有最低界面能的球形碳纳米洋葱。