铅于旋转银盘电极上欠电位沉积的计时库仑法研究

Investigation of Underpotential Deposition of Lead on Rotating Silver Disk Electrode by Chronocoulometry

用计时库仑法研究了Ｐｂ２＋于旋转Ａｇ盘电极（Ａｇ－ＲＤＥ）上的欠电位沉积（ＵＰＤ）性质。实验证明，支持电解质（０．０１ｍｏｌ／Ｌ ＨＮＯ３＋０．０１ ｍｏｌ／Ｌ ＮａＣＩ）中Ｃｌ－离子的存在有利于取得稳态条件下ＵＰＤ Ｐｂ的电量值。其氧化过程电量（Ｑａ），代表Ｐｂ２＋吸附单层被定量转化为ＵＰＤ Ｐｂ单层的量，Ｑａ的平均值为３９３．３μＣ／ｃｍ２，相应于２×１０－９ｍｏｌ／ｃｍ２Ｐｂ２＋表面复盖量。

The monolayer charge of lead underpotential deposition (UPD) was studied by chronocoulometry. On the rotating silver disk electrode (Ag-RDE), the monolayer charge of UPD lead could reaches steady state at different Pb2+ concentration levels by changing reduction time of UPD Pb2+. A supporting electrolyte solution of 0.01 mol/L HNO3 + 0.01 mol/L NaCl was used. The steady state charge measured was 393.3 muC/cm(2), which corresponded to a surface cover of 2 x 10(-9) mol/cm(2) Pb2+ on the electrode surface.