磷酸在GO插层阶段的功能化调控及机理

Functional Regulation and Mechanism of Phosphoric Acid in GO Intercalation Stage

针对氧化石墨烯(GO)制备过程中插层阶段的调控及机理研究对GO功能化应用于电极材料具有重要的研究意义.本文在改进Hummers法的基础上,向H_(2)SO_(4)插层剂中加入不同体积的H_(3)PO_(4),制备了不同氧化程度的GO.利用扫描电子显微镜(SEM)、X射线光电子能谱(XPS)和傅里叶变换红外光谱(FTIR)等表征手段,分析了不同氧化程度的GO的微观形貌、元素组成、氧化程度,以探究H_(3)PO_(4)在插层石墨过程中的作用机理;并采用循环伏安法(CV)和交流阻抗法(EIS)对不同H_(2)SO_(4)/H_(3)PO_(4)体积比下的GO进行电化学性能测试,分析了H_(3)PO_(4)对GO电化学性能的影响,以达到调控石墨的插层氧化从而提升GO导电性的目的.结果表明,单一的H_(2)SO_(4)使GO基面上的邻位二醇过度氧化造成孔洞,H_(3)PO_(4)的加入会扩大石墨层间距,使氧化剂更易进入石墨层间,并与1,2-二醇反应生成环状结构以起到保护基面的作用,从而提高GO的导电性.H_(3)PO_(4)作为辅助酸会协助H_(2)SO_(4)制备基面更加完整且氧化程度更高的GO,但其酸性较弱,不可完全代替H_(2)SO_(4)在氧化过程中的作用.

The research on the regulation and mechanism of the intercalation stage in the preparation of graphene oxide(GO)is of great significance for the functionalization of GO and its application in electrode materials.On the basis of the improved Hummers method,different volumes of H_(3)PO_(4)were added to the H_(2)SO_(4)intercalation agent to prepare GO with different oxidation degrees.Scanning electron microscopy(SEM),X-ray photoelectron spectroscopy(XPS),Fourier transform infrared spectroscopy(FTIR)and other characterization methods were used to analyze the microstructure,elemental composition and oxidation degree of different GO to explore the mechanism of H_(3)PO_(4)in the process of intercalation of graphite.The electrochemical properties of GO under different volumes of H_(3)PO_(4)were tested by cyclic voltammetry(CV)and electrochemical impedance spectroscopy(EIS).The effect of H_(3)PO_(4)on the electrochemical properties of GO was analyzed to achieve the purpose of improving the conductivity of GO by regulating the intercalation oxidation of graphite.The results show that the single H_(2)SO_(4)causes the excessive oxidation of the ortho-diol on the GO base surface to cause holes.The addition of H_(3)PO_(4)will expand the graphite layer spacing and make the oxidant easier to enter the graphite layer and react with 1,2-diol to form a ring structure to protect the base surface,thereby improving the conductivity of GO.As an auxiliary acid,H_(3)PO_(4)will assist H_(2)SO_(4)to prepare GO with more complete base surface and higher oxidation degree,but its acidity is weak and cannot completely replace the role of H_(2)SO_(4)in the oxidation process.The research results provide experimental support and theoretical support for the subsequent development of functionalized GO and its application in energy storage.