(湘潭大学 化工学院，湘潭 411105)
摘 要: 利用X射线衍射(XRD)、傅里叶变换红外光谱(FT-IR)、零电荷点pHPZC、循环伏安(CV)和电化学阻抗(EIS)等手段，研究镁铁水滑石(MgFe-LDHs)的表面化学性质，揭示其表面酸碱性与电化学性能的关系。结果表明：当Mg与Fe的摩尔比(n(Mg)/n(Fe))为3时MgFe-LDH (LDH-3)的结晶度最高，碱性最强，且远强于n(Mg)/n(Fe)为2的MgFe-LDH (LDH-2)和n(Mg)/n(Fe)为4的(LDH-4)的碱性。LDH-2的碱性略强于LDH-4的，但差异微小。层间CO32–与LDH层板金属离子主要形成单齿和双齿配位，其中，单齿配位体与强碱位点配位，形成Lewis碱位。表面碱性取决于Lewis强碱性位(CO32–单齿配位)的含量。用镁铁水滑石煅烧产物 (MgFe-LDOs) 修饰玻碳电极来研究其电化学性能。碱性越强(如LDO-3)，其氧化还原可逆性及导电性能越好。
关键字: 镁铁水滑石；表面酸碱性；配位；电化学性能；结晶度
（School of Chemical Engineering, Xiangtan University, Xiangtan 411105, China）
Abstract:The surface chemical characteristics of the Mg-Fe hydrotalcites (MgFe-LDHs) were determined using X-ray diffractometry (XRD), Fourier transform-infrared spectrometer (FT-IR), point of zero charge (pHPZC), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The relationship between the surfaceacid-base and electrochemical properties of the MgFe-LDHs was clarified. The results show that the MgFe-LDH with molar ratio of Mg to Fe (n(Mg)/n(Fe)) being 3 (LDH-3) has the highest crystallity structure with symmetrical crystals, indicating that the surface basicity of the LDH-3 is the strongest. And its basicity is much higher than those of ones with n(Mg)/n(Fe) of 2 (LDH-2) and 4 (LDH-4). The basicity of LDH-2 is slightly stronger than that of LDH-4. The monodentate and bidentate coordinations are formed by the interlayer CO32– anions coordinating with the metal ions in the brucite-like layers. The monodentate ligand coordinates with the strong basic sites, then Lewis basic sites form. The basicity depends on the content of Lewis basic sites. Mg-Fe hydrotalcite calcined samples (MgFe-LDOs) were used to modify glassy carbon electrode to study its electrochemical properties. The stronger the basicity (such as those of the LDO-3) is, the better the oxidation-reduction reversibility and conductivity are.
Key words: Mg-Fe hydrotalcite; urfaceacid-base property; coordination; electrochemical property; crystallinity
