Simulation of two-electron homogeneous electrocatalysis for steady-state voltammetry at hemispherical microelectrodes.
Simulation of two-electron homogeneous electrocatalysis for steady-state voltammetry at hemispherical microelectrodes.
复制标题
DOI：
10.1021/ac00202a009
复制
发表时间：
1990-02
影响因子：
7.4
通讯作者：
C. Miaw;J. Rusling;A. Owlia
中科院分区：
文献类型：
--
作者：
C. Miaw;J. Rusling;A. Owlia
将二阶双电子均相电催化的扩展空间网格数字模拟扩展到半球形微电极慢扫描伏安法。在一定的均相催化速率常数（k1）和电极半径范围内，对催化剂的可逆和准可逆非均相电荷转移进行了模拟预测。在扩散系数相等的条件下，得到了催化效率与长k1的工作曲线。当电极半径在小于10微米范围内减小时，需要更大的均相催化速率来产生分析上显著的极限电流放大。采用半球形半径为（2/pi）rd的模拟可用于预测半径为rd的微盘电极的催化效率。利用模拟的工作曲线估计，在碳微盘电极上获得的稳态催化效率中，电子从9,10-二苯基的阴离子自由基转移到4,4'-二溴联苯的对数k1为3.88 +/- 0.55 （M-1 s-1）。该值与先前循环伏安法测得的3.90 +/- 0.16 M-1 s-1相吻合。
Expanded space grid digital simulation of second-order, two-electron homogeneous electrocatalysis was extended to slow scan voltammetry at hemispherical microelectrodes. Predictions of the simulations are examined for reversible and quasireversible heterogeneous charge transfer of catalyst for a range of homogeneous catalytic rate constants (k1) and electrode radii. Working curves of catalytic efficiency vs long k1 were generated assuming reacting species with equal diffusion coefficients. As electrode radii in the less than 10-microns range decrease, progressively larger homogeneous catalytic rates are needed to yield analytically significant amplification of limiting currents. Simulations using hemispherical radii of (2/pi)rd can be used to predict catalytic efficiencies for microdisk electrodes with radii rd. Simulated working curves were used to estimate a log k1 of 3.88 +/- 0.55 (M-1 s-1) for electron transfer from the anion radical of 9,10-diphenylanthracene to 4,4'-dibromobiphenyl from steady-state catalytic efficiencies obtained at carbon microdisk electrodes. This value was in good agreement with 3.90 +/- 0.16 M-1 s-1 found previously by cyclic voltammetry.