Ti基IrO_2+Ta_2O_5涂层阳极的析氧电催化活性

ELECTROCATIALIC ACTIVITY FOR OXYGEN EVOLU- TION OF TITANIUM BASED IrO_2+Ta_2O_5 ANODES

通过极化曲线与电化学阻抗谱测试研究了Ｔｉ基ＩｒＯ２＋Ｔａ２Ｏ５阳极的析氧电催化活性．结果表明， ＩｒＯ２含量为７０％（摩尔分数）时，混合氧化物阳极表面具有最高的析氧活性．这缘于该成分含量阳极中活性组元ＩｒＯ２的真实表面浓度达到最大；而且，由于表面析出晶粒的最细化，在析氧电位下受析出氧气的冲击，该成分阳极表面的活性点数目得到最大程度的提高．由此提出决定氧化物阳极析氧电催化活性的热力学及动力学判据．

The electrocatalytic activity of titanium based IrO2+Ta2O5 anodes for oxygen evolution has been investigated by polarization and electrochemical impedance spectroscopy (EIS) techniques. It was shown that the mixed oxide anodes exhibited the highest activity at 70% (mole fraction) IrO2 content. Th-is result was interpreted by the maximum surface concentration of active component IrO2 with the corresponding composition and by the most significant increase of the amount of surface active site after attacking by the evaluated oxygen. Accordingly, the thermodynamic and kinetic criterions determining the electrocatalytic activity of oxide anodes for oxygen evolution have been proposed.