Hidden Second Oxidation Step of Hummers Method

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• 作者：Jong Hun Kang ; Taehoon Kim ; Jaeyoo Choi ; Jisoo Park ; Yern Seung Kim ; Mi Se Chang ; Haesol Jung ; Kyung Tae Park ; Seung Jae Yang ; Chong Rae Park
• 刊名：Chemistry of Materials
• 出版年：2016
• 出版时间：February 9, 2016
• 年：2016
• 卷：28
• 期：3
• 页码：756-764
• 全文大小：749K
• ISSN：1520-5002

文摘

Hummers method has been used for 50 years to prepare graphene oxide (GO) by oxidizing graphite using Mn₂O₇. In this work, a new angle on Hummers method is described. The oxidation procedure before the addition of water, which has been respected as the main oxidation step of Hummers method, is named step I oxidation, and the widely ignored further oxidation step after the addition of water is named step II oxidation. The chemical and structural evolutions during step II oxidation was demonstrated for the first time using various techniques including atomic force microscopy (AFM), dynamic light scattering (DLS), X-ray photoelectron spectroscopy (XPS), ultraviolet–visible light (UV–vis) spectroscopy, Fourier-transform infrared spectroscopy (FT-IR), ¹³C nuclear magnetic resonance (NMR), and zeta-potentiometry. Step II oxidation influences the size of GO, defects within the layers, and functional groups on the surface, which affect the thermal stability of GO and the properties of resultant thermally reduced GO. This work provides new chemical insights into GO and guidelines for preparation of tailor-fitted GO.