歧化
电子转移
化学
电化学
循环伏安法
无机化学
氧化还原
水溶液
吸附
反应机理
速率决定步骤
扩散
电极
光化学
物理化学
催化作用
有机化学
热力学
物理
作者
Wei Jin,Michael S. Moats,Shili Zheng,Hao Du,Yi Zhang,Jan D. Miller
标识
DOI:10.1016/j.electacta.2011.06.110
摘要
The electrochemical oxidation of aqueous Cr(III) was examined using cyclic voltammetry with a polycrystalline Au electrode in KOH solutions of varying pH and Cr(III) concentration. The mechanism and kinetics for the oxidation of Cr(III) is a quasi-reversible diffusion-controlled reaction and is largely dependent on the solution pH. The reaction mechanism is initiated by an irreversible electrochemical electron transfer to form Cr(IV) which is the rate-determining step (RDS). Following the RDS, subsequent oxidation of Cr to its hexavalent state occurs by the disproportionation of Cr(IV) at low KOH concentrations and electron transfer at high KOH concentrations due to the involvement of OH− in the disproportionation reaction. As the solution pH increases, the Cr(III) oxidation peak potential shifts negatively owing to the involvement of OH− in the RDS. The competitive adsorption of OH− and CrO2− on the electrode surface also plays an important role in the oxidation behavior.
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