P_2O_8^（4－）离子阳极形成动力学与机理以及添加剂的影响

KINETICS AND MECHANISM OF P_2O_8￣(4-) ANODIC FORMATION PROCESSES AND EFFECT OF ADDITIVES ON THE ANODIC PROCESSES AT Pt ELECTRODE

本文用分极化曲线法研究了Ｐｔ电极上ＨＰＯ阳极氧化为Ｐ２Ｏ的动力学与机理．由分解得到的Ｏ２和Ｐ２Ｏ的极化曲线的Ｔａｆｅｌ斜率，低极化区两者均为２．３０３ＴＲ／βＦ；而高极化区两者分别为２．３０３ＲＴ／２βＦ和２．３０３ＲＴ／βＦ（其中β≈０．５）．两者的动力学方程分别为：低极化区：高极化区：此外，还研究了Ｆ－、Ｃｌ－、ＳＣＮ－和（ＮＨ２）２ＣＳ等添加剂对上述两过程分别的影响．发现Ｆ－离子在低极化区对两者均有加速作用，但对ｉ（Ｏ２）的加速作用要大于对ｉ（Ｐ２Ｏ）的加速作用，故使电流效率降低；在高极化区，Ｆ－离子对两者均有阻滞作用，当［Ｆ－］＜２ｍｏｌ／Ｌ时，由于对ｉ（Ｏ２）的阻滞作用要大于对ｉ（Ｐ２Ｏ）的阻滞作用，故使电流效率提高．

The kinetic data related respectively to P2O anodic formation and O2 anodic evolution at Pt electrode in mixed K2 HPO4-KOH-KF solutions were obtained by method of resolving the steady-state polarization curve.Stead-state～log i relationships for P2O anodic formation and O2 evolution reaction Tafel slope are close to 2.303 RT/βF in the low polarization region.However,in the high polarization region,the Tafel slope for P2O anodic formation is close to2.303 RT/βF,whereas for O2 anodic evolution it is close to 2. 303 RT /2βF(with β=0.5).It is shown by experiments that the anodic formation of P2O and O2 anodic evolution atPt electrode in the low polarization region and in the high polarization region are described bythe equation:and respectively.In addition to that,the influences of F-,CI-,SCN-,(NH2),CS on the above-mentionedprocesses were investigated.The results indicate that in the low polarization region (>1.9 V,vs.SCE),F- ions accelerate the both processes,but inhibit the both processes in the high po-larization region(>1.9V,vs. SCE)