Electron Hopping of Tris (2,2 ′ -bipyridyl) Transition Metal Complexes M(bpy) 2/3 3 in Nafion
Electron Hopping of Tris (2,2 ′ -bipyridyl) Transition Metal Complexes M(bpy) 2/3 3 in Nafion
复制标题
Nafion 中 Tris (2,2 – 联吡啶) 过渡金属配合物 M(bpy) 2/3 3 的电子跳跃
DOI：
10.1149/2.1121607jes
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发表时间：
2016
影响因子：
3.9
通讯作者：
Leddy, Johna
中科院分区：
文献类型：
--
作者：
Gellett, Wayne L.;Knoche, Krysti L.;Rathuwadu, Nadeesha P.;Leddy, Johna
电极上薄膜中过渡金属络合物的伏安电流随着电子自交换（跳跃）速率 k 11 的增加而增加。在薄膜中，扩散系数 D f∝ k 11 c* f，其中 k 11 设置电子跳跃尝试的频率，c* f 薄膜浓度设置探针之间的距离。对六个探针、三 (2, 2'-联吡啶) 络合物 M (bpy) z+ 3 的电极上的 Nafion 薄膜进行循环伏安法，其中 M z+ 是 Ru 2+、Os 2+、Fe 2+、Cr 3+、Co 3+ 和 Co 2+，证明 D f 随 k H 2 O 11 线性变化，文献 k 11 在水中测量。根据 Ru (bpy) 2+ 3 交换 Nafion 的密度 1.95 g/cm 3 和标称当量 1100，几何形状为所有 M (bpy) z+ 3 建立体积受限、z 独立的 c* f。对于 HNO 3 中 Ru (bpy) 2+ 3 的浓度，其中 Ru (bpy) 2+ 3: HNO 3 比率固定或 Ru (bpy) 2+ 3 为 1 mM和 HNO 3 变化，c* f 统计上不变。基于水滴定和足以支持离子的介电常数，电子跳跃被限制在 Nafion 的水合区域。根据c* f，Nafion 中的k 11 k Naf 11 估计为，与Nafion 中较高的离子浓度一致。对于 Ru (bpy) 2+ 3 和 Os (bpy) 2+ 3，测得的 D f 为 2× 10− 9 cm 2/s； Fe (bpy) 2+ 3 和 Cr (bpy) 3+ 3 为 1× 10− 10 cm 2/s； Co (bpy) 2+ 3 和 Co (bpy) 3+ 3 为 1.5× 10− 12 和 5× 10− 12 cm 2/s。物理扩散 D p≲ 10− 12 cm 2/s。概述了 Nafion 中 M (bpy) z+ 3 自交换的自洽观点。对于Os (bpy) 2/3 3，k H 2 O 11 ≈ 4.5× 10 8/Ms。
Voltammetric currents of transition metal complexes in films on electrodes increase with electron self exchange (hopping) rate k 11. In films, diffusion coefficients D f∝ k 11 c* f, where k 11 sets frequency of electron hopping attempts and c* f film concentration sets distance between probes. Cyclic voltammetry of Nafion films on electrodes for six probes, tris (2, 2'-bipyridyl) complexes, M (bpy) z+ 3 where M z+ is Ru 2+, Os 2+, Fe 2+, Cr 3+, Co 3+, and Co 2+, demonstrates D f varies linearly with k H 2 O 11, literature k 11 measured in water. From density of Ru (bpy) 2+ 3 exchanged Nafion 1.95 g/cm 3 and nominal equivalent weight 1100, geometry establishes volume limited, z-independent c* f for all M (bpy) z+ 3. For concentrations of Ru (bpy) 2+ 3 in HNO 3 where either Ru (bpy) 2+ 3: HNO 3 ratio is fixed or Ru (bpy) 2+ 3 is 1 mM and HNO 3 varies, c* f is statistically invariant. Based on aqueous titrations and dielectric constant sufficient to support ions, electron hopping is confined to hydrated domains of Nafion. From c* f, k 11 in Nafion k Naf 11 is estimated as, consistent with higher ion concentration in Nafion. Measured D f is 2× 10− 9 cm 2/s for Ru (bpy) 2+ 3 and Os (bpy) 2+ 3; 1× 10− 10 cm 2/s for Fe (bpy) 2+ 3 and Cr (bpy) 3+ 3; and 1.5× 10− 12 and 5× 10− 12 cm 2/s for Co (bpy) 2+ 3 and Co (bpy) 3+ 3. For physical diffusion D p≲ 10− 12 cm 2/s. A self consistent view of M (bpy) z+ 3 self exchange in Nafion is outlined. For Os (bpy) 2/3 3, k H 2 O 11≈ 4.5× 10 8/Ms.