Fully Converting Graphite into Graphene Oxide Hydrogels by Preoxidation with Impure Manganese Dioxide

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• 作者：Jiaojiao Sun ; Ningxin Yang ; Zhe Sun ; Mengqi Zeng ; Lei Fu ; Chengguo Hu ; Shengshui Hu
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2015
• 出版时间：September 30, 2015
• 年：2015
• 卷：7
• 期：38
• 页码：21356-21363
• 全文大小：510K
• ISSN：1944-8252

文摘

Potassium permanganate (KMnO₄) has been proved to be an efficient oxidant for converting graphite into graphite oxide, but its slow diffusion in the interlayer of graphite seriously restricts the production of graphene oxide (GO). Here, we demonstrate that the preoxidation of graphite by impure manganese dioxide (MnO₂) in a mixture of concentrated sulfuric acid (H₂SO₄) and phosphorus pentoxide (P₂O₅) can efficiently improve the synthesis of GO when KMnO₄ is employed as the oxidant. The prepared honey-like GO hydrogels possess a high yield of single-layer sheets, large sizes (average lateral size up to 20 渭m), wide ranges of stable dispersion concentrations (from dilute solutions, viscous hydrogels, to dry films), and good conductivity after reduction (鈭?.9 脳 10⁴ S/m). The mechanism for the improved synthesis of GO by impure MnO₂ was explored. The enhanced exfoliation and oxidation of graphite by oxidative Mn ions (mainly Mn³⁺), which are synergistically produced by the reaction of impure MnO₂ with H₂SO₄ and P₂O₅, are found to be responsible for the improved synthesis of such GO hydrogels. Particularly, preoxidized graphite (POG) can be partially dispersed in water with sonication, which allows the facile construction of flexible and highly conductive graphene nanosheet film electrodes with excellent electrochemical sensing properties.