Dynamics of charge transport through osmium tris dimethoxy bipyridyl solid deposits
Dynamics of charge transport through osmium tris dimethoxy bipyridyl solid deposits
复制标题
三二甲氧基联吡啶固体沉积物的电荷传输动力学
作者：
L. Keane;C. Hogan;R. Forster
在铂微电极上形成了[Os（OMe-bpy）_3]（PF_6）_2固体沉积物，其中OMe-bpy为4，4 ′-二甲氧基，2- 2 ′-联吡啶.与Os 2 + / 3 +氧化还原过程的伏安法是接近理想的支持电解质是0. 1 M的HClO 4，并建议，在沉积物内的氧化还原中心溶剂化。扫描电子显微镜显示，在伏安循环之前，沉积物作为微观颗粒的阵列存在。相反，在高氯酸中伏安循环后，存款变成薄片形式的微晶。当沉积物在中性电解液中循环时，没有观察到电结晶，这表明甲氧基的质子化在该过程中起着重要作用。当支持电解质为HClO 4时，在半无限线性扩散条件下进行的伏安法测得0.1 ≤ [HClO 4 ] ≤ 0.6 M时的均匀电荷传输扩散系数DCT为1.5 ′ 0.1 × 10 - 9 cm 2 s - 1。相比之下，高于0.6 M HClO 4时，D C T显著增加，在1.0 M HClO 4中达到13 ′ 1 x 10 - 9 cm 2 s - 1。根据Dahms-Ruff方程对这些数据进行分析，得出自交换速率常数为5.7 x 10 6 M - 1 s - 1。用高扫描速率伏安法（5 ≤ 100 V s - 1）测定了标准非均相电子转移速率常数k°，固相为1.0 ′ 0.05 × 10 - 4，溶液为6.1 ′ 0.2 × 10 - 5 cm s - 1。
Solid deposits of [Os(OMe-bpy) 3 ](PF 6 ) 2 have been formed on a platinum microelectrode, where OMe-bpy is 4,4'-dimethoxy, 2-2'-dipyridyl. The voltammetry associated with the Os 2 + / 3 + redox processes is nearly ideal where the supporting electrolyte is 0.1 M HClO 4 and suggests that the redox centers within the deposits are solvated. Scanning electron microscopy reveals that prior to voltammetric cycling, the deposits exist as an array of microscopic particles. In contrast, after voltammetric cycling in perchloric acid the deposit becomes microcrystalline in the form of thin plates. Electrocrystallization is not observed when the deposits are cycled in neutral electrolyte suggesting that protonation of the methoxy groups plays an important role in the process. Where the supporting electrolyte is HClO 4 , voltammetry conducted under semi-infinite linear diffusion conditions yields a homogeneous charge transport diffusion coefficient, D C T , of 1.5 ′ 0.1 x 10 - 9 cm 2 s - 1 for 0.1 ≤ [HClO 4 ] ≤ 0.6 M. In contrast, above 0.6 M HClO 4 D C T increases significantly reaching 13 ′ 1 x 10 - 9 cm 2 s - 1 in 1.0 M HClO 4 . Analysis of these data according to the Dahms-Ruff equation yields a self-exchange rate constant of 5.7 x 10 6 M - 1 s - 1 . High scan rate voltammetry, 5 ≤ υ ≤ 100 V s - 1 , has been used to determine the standard heterogeneous electron transfer rate constant, k°, as 1.0 ′ 0.05 x 10 - 4 and 6.1 ′ 0.2 x 10 - 5 cm s - 1 for solid and solution phase, respectively.