Ti／IrO2-Ta2O5阳极的制备及其析氧电催化性能研究

通过热氧化技术在500℃条件下制备了一系列Ti／IrO2-Ta2O5阳极。采用线性扫描和循环伏安技术分析了不同铱钽比阳极涂层的析氧电流、电位和伏安电荷的变化规律，并结合扫描电镜（SEM）及X射线衍射（XRD）技术研究了Ti／IrO2-Ta2O5阳极的表面形貌、组成、结构对析氧电催化性能的影响。研究表明，在IrO2-Ta2O5涂层中，铱钽由于存在一定的互溶度而形成固溶体结构，铱钽互溶度与涂层中铱钽比有关且影响IrO2晶胞的大小。随着涂层组元IrO2含量的增加，涂层表面细小的IrO2晶体聚集体增多，析氧电催化活性增强；但当IrO2含量过多时，涂层附着力的下降和机械强度的降低对析氧电催化性能产生负面影响。IrO2-Ta2O5涂层的活性表面积不仅取决于活性组元IrO2的含量，还与涂层的结构有关。适宜的铱钽比才具有最大的催化活性。其原因可能在于涂层中加入的适量惰性元素钽与IrO2晶胞形成部分固溶体结构，增强了涂层附着力与机械强度，同时形成了多裂纹的网状表面结构，增加了涂层活性表面积，提高了电极的析氧电催化活性与电解稳定性。

Preparation and Characterization of Ti/IrO2-Ta2O5 Anodes for Oxygen Evolution Used to Sulfate Electrolysis

In this paper, Ti/IrO2-Ta2O5 anodes with different ratios of IrO2 were prepared by thermolytic decomposition method for sulfate electrolysis. The structure and morphologies of the oxide films were determined by XRD and SEM, respectively. Linear Sweep Voltammetry, Tafel Plot and Cyclic Voltammetry were used to characterize their electrochemical activities of oxygen evolution. Test results show that the iridium and tantalum could form solid solution structure. The mutual solubility between iridium and tantalum is affected by the ratio of Ir/Ta in coating solution and influences the dimension parameters of IrO2 crystals. The finer IrO2 crystallites increase on the coating surface and the electrocatalytic capability of oxygen evolution is strengthened with the increasing of IrO2 content in the coatings. When the content of IrO2 is too high, the coating adhesion and rigidity would decrease which affect electrochemical activity of the anode. The electrochemically active surface area is determined not only by the content of IrO2, but also the structure and morphology of the anode coatings. It is probably due to the existence of proper quantities of inert Ta2O5, resulting in a typical morphology of cracks and solid solution structure. The solid solution structure is helpful to prolong the anode service life. The morphology of cracks could perhaps improve the anode active surface area and the electrocatalytic activity of oxygen evolution.