【摘要】 结合线性电位扫描、开路计时电位和交流阻抗技术研究了Fe在硼酸盐缓冲溶液(pH=8 4)中不同电位区间的界面性质.在氮气气氛下,电位低于-0 77V,界面发生析氢反应,反应受电子转移步骤控制,同时存在氢原子的表面吸附过程;-0 77V至0 60V间,Fe氧化成2价Fe而发生活性溶解,同时2价Fe进一步氧化成3价Fe,二步反应均受电子转移步骤控制;至0 60V,形成具有保护作用的单层Fe3O4;-0 60V至-0 50V间,Fe氧化成2价Fe的反应随电位升高而变慢,表现为负的反应电阻;-0 50V至0 90V间,Fe进入钝化区,较低电位下主要是Fe3O4转化成Fe2O3的过程,受电子转移步骤和OH-在钝化膜中的扩散步骤混合控制,较高电位下Fe直接氧化成3价Fe,受电子转移步骤和3价Fe离子在钝化膜中的扩散步骤混合控制;电位高于0 90V,界面发生析氧反应和氧化膜溶解,反应受电子转移步骤控制,反应过程中有中间产物吸附.更多还原

【Abstract】 The interface performances of iron/borate buffer sloution (pH=84) are investigated by using linear potential sweep voltammetry, open circuit chronopotentiometry, and alternative current (AC) impedance spectroscopy. At the potential lower than -077 V under nitrogen atmosphere, hydrogen evolution reaction controlled by electron transfer step takes place on the iron surface, accompanied with the hydrogen adsorption. At the potential from -077 to -060 V, iron is in its active state and dissolves forming Fe (Ⅱ), accompanied with the formation of Fe(Ⅲ). Both the formations of Fe(Ⅱ) and Fe(Ⅲ) are controlled by the electron transfer step. At -066 V, monolayer Fe3O4 forms, which can prevent iron from active dissolution. At the potential from -066 V to -050 V, iron is in its active-passive region; the Fe(Ⅱ) formation is inhibited with increasing anodic potential, which can be shown by the appearance of negative resistance. At the potential from -050 V to 090 V, iron is in its passive state. At the lower potential in the passive region, Fe3O4 is oxidized to form Fe2O3, which is controlled by the electron transfer and the transport of OH- in the passive film. At the higher potential in the passive region, iron is oxidized directly to Fe2O3, which is controlled by the electron transfer and the transport of Fe(Ⅲ) in the passive film. At the potential higher than 090 V, oxygen evolution and passive film dissolution reactions controlled by electron transfer step take place, accompanied with an adsorption process of the reaction intermediate.更多还原