钛基导电氧化物电极上氧的阳极析出动力学与机理研究

本文通过在碱溶液中Ti/RuO_2+TiO_2(A)和Ti/SnO_2+CuCo_2O_4(B)电极上氧阳极析出动力学的对比研究, 表明这两类电极上氧的极化曲线均有两Tafel区。低极化区的Tafel斜率为0.039V(简称b_1区); 高极化区为0.120V(简称b_2区)。在A电极上b_1区i～a_W·a_(OH~-); b_2区i～a_W(浓碱溶液)或i～a_(OH)~(0.1～0.5)(稀碱溶液),在B电极上b_1区i～a_(OH~-); b_2区i～a_(OH~-)~(0.39)(浓碱溶液);或i～a_(OH~-)(稀碱溶液), 实验结果表明, 虽然这两类电极上氧阳极析出过程都由第二电子转移步骤控制, 但其机理不同, 前者是由水分子参加, 控制步骤为RuO_2·OH_(ads)+H_2O ~(rds)→ RuO(OH)~+_3+e后者则为 (SOH)~(n+)_(ads) ~(rds)→ (SOH)~((n+1)+)_(ads)+e它们与PbO_2、Pt和低碳钢上机理有些不同~1,2]。

KINETICS AND MECHANISM OF OXYGEN ON CONDUCTIVE METALLIC OXIDES-COATED TITANIUM ANODES IN ALKALINE SOLUTION

Ti/RuO_2+TiO_2 and Ti/SnO_2+CuCo_2O_4 anodes were used to study oxygen evolution in alkaline solutions and to compare the kinetics on both electrodes.On both electrodes the existence of two Tafel regions are confirmed. At low cd's ψ/lgi=2.303RT/(1+β)F and at high cd's it is 2.303RT/βF.On Ti/SnO_2+CuCo_2O_4 electrodes the reaction order with respect to α_(OH)- is 1 in the/low cd region. For the high cd region the reaction orders are 0.33 and 1 in concentrated alkaline and dilute alkaline solutions respectively.On Ti/RuO_2+TiO_2 electrodes, the reaction order with respect to a_W a_(OH~-) is 1 in the low cd region. For the high cd region, the reaction order with respect to a_W is 1 in concentrated alkaline solutions, and the reaction order with respect to a_(OH~-) is 0.1~0.5 in dilute alkaline solutions.The kinetic data obtained show that the rate determing stept of anodic evolution of oxygen areRuO_2·OH_(ads)+H_2O→RuO(OH)~+_3+eand (SOH)~(n+)_(ads)→(SOH)~((n+1)+)_(ads)+eon Ti/RuO_2+TiO_2 electrode and Ti/SnO_2+CuCo_2O_4 electrode, respectively.