Voltammetric Responses of Surface-Bound and Solution-Phase Anthraquinone Moieties in the Presence of Unbuffered Aqueous Media
Voltammetric Responses of Surface-Bound and Solution-Phase Anthraquinone Moieties in the Presence of Unbuffered Aqueous Media
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DOI：
10.1021/jp1096585
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发表时间：
2011-01-27
影响因子：
3.7
通讯作者：
Compton, Richard G.
中科院分区：
文献类型：
--
作者：
Batchelor-McAuley, Christopher;Kozub, Barbara R.;Compton, Richard G.
已知涉及质子转移的溶液相氧化还原物质的伏安法在非缓冲介质的条件下定性地改变（Quan，M.等.美国2007，129，12847 -12856）。我们现在首先报告在有限浓度的质子存在下，溶液相蒽醌单磺酸盐在金大电极上的伏安响应;此外，我们提供了在非缓冲条件下的伏安法的定量分析，由此可以通过模拟来证明，在某些条件下，与本体溶液相比，电极处的pH可以改变高达5-6个pH单位。电极附近的局部环境的这种变化是由电化学过程中质子的消耗引起的。因此，在低缓冲条件下，电化学还原受到质子可用性的限制，导致测量的伏安信号具有两个伏安波。第二，在有限质子浓度条件下研究了蒽醌修饰热解石墨电极。我们实验演示了如何发生类似的分裂波结果的表面限制的物种。这些结果提供了在电化学过程中质子消耗的物理见解，并强调如何使用氧化还原修饰电极表面的pH测量方法是非被动的。
The voltammetry of solution-phase redox species involving proton transfer are known to be qualitatively altered under conditions of nonbuffered media (Quan, M. et al. J. Am. Chem. Soc. 2007, 129,12847-12856). We now report first the voltammetric response of solution-phase anthraquinone monosulphonate on a gold macroelectrode in the presence of a limited concentrations of protons; further we provide quantitative analysis of the voltammetry under unbuffered conditions whereby it is possible to demonstrate through simulation that in some conditions the pH at the electrode may alter by up to 5-6 pH units as compared to that of the bulk solution. This change in local environment adjacent to the electrode is caused by the consumption of protons during the electrochemical process. As a result, in conditions of low buffering the electrochemical reduction is limited by the availability of protons, leading to a measured voltammetric signal with two voltammetric waves. Second the work is developed through the study of an anthraquinone modified pyrolytic graphite electrode under conditions of finite proton concentration. We demonstrate experimentally how analogous split wave results occur for surface confined species. These results provide physical insight into the consumption of protons during the electrochemical process and highlight how methods of pH measurement based upon the use of redox modified electrode surfaces are nonpassive.