含氟电解液中钛基铱钽氧化物电极的稳定性

Stability of Titanium-based IrO2-Ta2O5 Electrode in Electrolyte Containing Fluorine

目的分析钛基铱钽氧化物电极在含氟电解液中的应用前景。方法采用热分解法制备出钛基铱钽氧化物电极,借助扫描电镜分析了氟元素对钛基铱钽氧化物电极表面形貌的影响。应用循环伏安、稳态极化和电化学阻抗等方法,研究了氟元素对铱钽氧化物电极在硫酸溶液中电催化性能的影响。结果当溶液中的氟含量高于5mg/L时,铱钽氧化物电极在2A/cm^2下强化电解72h后,表面开始出现裂纹,且裂纹尺寸和数量随溶液中氟含量的增加而增加。强化电解72h下,氟含量低于10mg/L时,氟对钛基铱钽氧化物电极循环伏安特性的影响较小,但氟含量高于10mg/L时,电极伏安面积可增大24%。强化电解过程中,氟元素可增加电极的电荷转移电阻,增大电极的析氧电位,降低电极的双电层电容。结论电解液中的氟元素可加速钛基铱钽氧化物电极的失效。氟元素虽可提高电极表面的粗糙度,改善电催化性能,但活性成分氧化铱的溶解损失更大,导致电极的析氧电催化性能降低。钛基铱钽氧化物电极在氟含量低于5mg/L的酸性电解液中具有应用前景。

The work aims to analyze the application prospect of titanium-based IrO2-Ta2O5 oxide electrodes in the electrolyte containing fluorine.The titanium-based Ir-Ta oxide electrodes were prepared by thermal decomposition.The effect of fluorine on morphology of titanium-based IrO2-Ta2O5 oxide electrodes was analyzed via scanning electron microscopy.The effect of fluorine on electrocatalysis of IrO2-Ta2O5 mixed oxide electrodes in H2SO4 solution was also studied by cyclic voltammetry,stable polarization,and electrochemical impedance spectroscopy.Based on experiment results,the cracks appeared in the IrO2-Ta2O5 mixed oxide electrodes after accelerated electrolysis at 2 A/cm^2 for 72 h when fluorine content was higher than 5 mg/L,and the size and amount of crack increased with increasing fluorine content.When fluorine content was below 10 mg/L, it had little influence on CV feature of IrO2-Ta2O5 mixed oxide electrodes during accelerated electrolysis for 72 h,but fluorine content of 10 mg/L lead to increase of cyclic voltammetry area by 24%.Fluorine could increase potential of oxygen evolution and charge transfer resistance,and reduce the double layer capacitance.Fluorine in the electrolyte may accelerate the failure of titanium-based Ir-Ta oxide electrodes.Although fluorine can improve the surface roughness and electrocatalytic performance of the electrodes,the electrocatalytic property of the electrode for oxygen evolution decreases in view of high dissolution of iridium oxide of the electrodes.Titanium-based IrO2-Ta2O5 mixed oxide electrodes have application prospect in acidic electrolyte with fluorine content less than 5 mg/L.