Key Laboratory of Nanodevices and Applications, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou, Jiangsu, 215123, P. R. China.
Small. 2014 Apr 9;10(7):1421-9. doi: 10.1002/smll.201302730. Epub 2013 Dec 9.
A facile and high-yield approach to the preparation of few-layer graphene (FLG) by electrochemical intercalation exfoliation (EIE) of expanded graphite in sulfuric acid electrolyte is reported. Stage-1 H2SO4-graphite intercalation compound is used as a key intermediate in EIE to realize the efficient exfoliation. The yield of the FLG sheets (<7 layers) with large lateral sizes (tens of microns) is more than 75% relative to the total amount of starting expanded graphite. A low degree of oxygen functionalization existing in the prepared FLG flakes enables them to disperse effectively, which contributes to the film-forming characteristics of the FLG flakes. These electrochemically exfoliated FLG flakes are integrated into several kinds of macroscopic graphene structures. Flexible and freestanding graphene papers made of the FLG flakes retain excellent conductivity (≈24,500 S m(-1)). Three-dimensional (3D) graphene foams with light weight are fabricated from the FLG flakes by the use of Ni foams as self-sacrifice templates. Furthermore, 3D graphene/Ni foams without any binders, which are used as supercapacitor electrodes in aqueous electrolyte, provide the specific capacitance of 113.2 F g(-1) at a current density of 0.5 A g(-1), retaining 90% capacitance after 1000 cycles.
本文报道了一种在硫酸电解质中通过电化学插层剥离（EIE）膨胀石墨来制备少层石墨烯（FLG）的简便高产方法。阶段 1 的 H2SO4-石墨插层化合物被用作 EIE 中的关键中间体，以实现有效的剥离。相对于起始膨胀石墨的总量，具有大的横向尺寸（数十微米）的 FLG 片（<7 层）的产率超过 75%。在制备的 FLG 薄片中存在的低程度的氧官能化使它们能够有效地分散，这有助于 FLG 薄片的成膜特性。这些电化学剥离的 FLG 薄片被集成到几种宏观石墨烯结构中。由 FLG 薄片制成的柔性和自立的石墨烯纸保留了优异的导电性（≈24,500 S m(-1)）。通过使用 Ni 泡沫作为自牺牲模板，从 FLG 薄片制备了具有轻重量的三维（3D）石墨烯泡沫。此外，作为超级电容器电极在水性电解质中使用的无任何粘结剂的 3D 石墨烯/Ni 泡沫在 0.5 A g(-1)的电流密度下提供了 113.2 F g(-1)的比电容，在 1000 次循环后保留了 90%的电容。
