Adsorption and Electron-Transfer Mechanisms of Ferrocene Carboxylates and Sulfonates at Highly Oriented Pyrolytic Graphite
Adsorption and Electron-Transfer Mechanisms of Ferrocene Carboxylates and Sulfonates at Highly Oriented Pyrolytic Graphite
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DOI：
10.1002/celc.201901664
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发表时间：
2019-11-18
期刊：
影响因子：
4
通讯作者：
Amemiya, Shigeru
中科院分区：
文献类型：
--
作者：
Kurapati, Niraja;Pathirathna, Pavithra;Amemiya, Shigeru
二茂铁衍生物被认为是代表性的外层氧化还原对，不专门与电极表面相互作用。然而，要在实验上明确地证明它们的外层性质是非常具有挑战性的。在此，我们采用定量循环伏安法来评估是否二茂铁羧酸盐和磺酸盐介导的高取向热解石墨（HOPG）的外层电子转移（ET）。我们发现伏安法，只有还原形式的ferroceneacetate，ferrocenecarboxylate，和ferrocenesulfonate专门吸附在HOPG表面介导的外层ET没有内球ET，这需要吸附的还原和氧化形式的氧化还原对。相比之下，1，1 '-二茂铁二羧酸盐和1，1'-二茂铁二磺酸盐的吸附伏安特征不明显，这妨碍了我们根据Laundry-Amatore悖论确定外层ET、内层ET以及两者的独特机理。
Ferrocene derivatives are considered as representative outer-sphere redox couples that do not specifically interact with the electrode surface. It, however, is highly challenging to unambiguously prove their outer-sphere character experimentally. Herein, we employ quantitative cyclic voltammetry to assess whether ferrocene carboxylates and sulfonates mediate only outer-sphere electron transfer (ET) at highly oriented pyrolytic graphite (HOPG). We find voltammetrically that only reduced forms of ferroceneacetate, ferrocenecarboxylate, and ferrocenesulfonate are specifically adsorbed on the HOPG surface to mediate outer-sphere ET without inner-sphere ET, which requires the adsorption of both reduced and oxidized forms of a redox couple. By contrast, no voltammetric feature of adsorption is observed for 1,1 '-ferrocenedicarboxylate and 1,1 '-ferrocenedisulfonate to prevent us from identifying the unique mechanism among outer-sphere ET, inner-sphere ET, and both owing to the Laviron-Amatore paradox.