Abstract

In this work we have tested the Fe(III)/(II) redox potential of the catalysts as a reactivity descriptors of iron macrocyclic complexes (FeN4) adsorbed on multi-walled carbon nanotubes (MWCNTs) and deposited on ordinary pyrolytic graphite (OPG). The reaction examined is the oxidation of glutathione (GSH) a biologically important molecule. The experiments were conducted in 0.1 M NaOH and kinetic measurements were performed on MWCNT previously modified with FeN4 macrocycle complexes. This modified FeN4–MWCNTs were deposited on pristine OPG electrodes. From previous work it is known that for FeN4 complexes directly adsorbed on OPG, the activity as (log i)_E plotted versus the Fe(II)/(I) redox potential follows a volcano correlation for the oxidation of glutathione. We wanted to test these correlations on hybrid electrodes containing MWCNTs and essentially the carbon nanotubes have no influence in these correlations and the redox potentials a are good reactivity descriptors, regardless of the way the FeN4 catalysts are attached to the electrode. Further, we find volcano correlations when using the Fe(II)/(I) and the Fe(III)/(II) redox potentials as reactivity descriptors. The volcano correlation when using the Fe(III)/(II) redox potential exhibits a maximum at E° = –0.26 V vs SCE which is close to the potential for comparing the different activities. This interesting result seems to indicate that the maximum cannot be explained only in terms of the Sabatier principle where θ_RS, the surface coverage of adsorbed intermediate is close to 0.5 but instead to a surface coverage of active sites θ_Fe(II) equal to 0.5, which occurs at the Fe(III)/(II) formal potential.

中文翻译：

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测试反应性描述符对铁大环配合物和MWCNT修饰的OPG杂化电极在碱性介质中氧化还原型谷胱甘肽的电催化活性

抽象的

在这项工作中，我们测试了催化剂的Fe（III）/（II）氧化还原电势作为吸附在多壁碳纳米管（MWCNT）上并沉积在普通热解石墨（OPG）上的铁大环络合物（FeN4）的反应性指标。 。检查的反应是谷胱甘肽（GSH）的氧化，这是生物学上重要的分子。实验在0.1 M NaOH中进行，动力学测量是在预先用FeN4大环配合物修饰的MWCNT上进行的。这种改性的FeN4-MWCNTs沉积在原始的OPG电极上。从以前的工作中可以知道，对于直接吸附在OPG上的FeN4络合物，其活性为（log  i）_E绘制的曲线与Fe（II）/（I）的氧化还原电位遵循了谷胱甘肽氧化的火山相关性。我们希望在包含MWCNT的混合电极上测试这些相关性，并且基本上碳纳米管对这些相关性没有影响，并且氧化还原电势a是良好的反应性描述子，而与FeN4催化剂与电极的连接方式无关。此外，当使用Fe（II）/（I）和Fe（III）/（II）氧化还原电势作为反应性描述符时，我们发现了火山的相关性。使用Fe（III）/（II）氧化还原电位时的火山相关性在E处表现出最大值°= –0.26 V vs SCE，接近比较不同活动的电势。这个有趣的结果似乎表明，最大可以不仅在沙巴提耶原则来解释其中θ _RS，吸附中间表面覆盖率接近0.5而代之以活性位点θ的表面覆盖度_{的Fe（II）}等于0.5 ，它以Fe（III）/（II）形式势发生。