Molecular conductance versus inductive effects of axial ligands on the electrocatalytic activity of self-assembled iron phthalocyanines: The oxygen reduction reaction
Molecular conductance versus inductive effects of axial ligands on the electrocatalytic activity of self-assembled iron phthalocyanines: The oxygen reduction reaction
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DOI：
10.1016/j.electacta.2019.134996
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发表时间：
2019-12-10
影响因子：
6.6
通讯作者：
Ponce, Ingrid
中科院分区：
文献类型：
--
作者：
Gutierrez-Ceron, Cristian;Onate, Ruben;Ponce, Ingrid
在自组装单分子膜修饰的金电极上构建酞菁铁（FePc）体系是一种获得氧还原反应（ORR）电催化分子构件的有趣策略。在这项工作中，我们在单分子水平上测量了吡啶鎓轴向配体的电导，使用基于扫描隧道显微镜的断裂结方法（STM-Break Junction）来研究轴向配体对自组装FePc体系在金电极表面的活性的作用。吡啶鎓轴向配体的电子拉动效应是已知的，以提高铁酞菁的氧还原反应（ORR）的电催化活性。我们已经使用这些系统作为一个平台进行比较研究，了解近端轴向配体的真实的影响。此外，这些配体作为金电极表面和FePc分子之间的分子导线。吡啶鎓分子是使用基本分子骨架在一系列结构变化之后合成的。从每个吡啶鎓分子获得的电导测量，可以确定通过每个吡啶鎓的电子传输不影响FePc在碱性介质中ORR的活性。此外，DFT计算表明，FePc中的轴向配体通过降低O-2与Fe位的结合能来改变其催化活性. (C)2019爱思唯尔有限公司版权所有。
The construction of self-assembled iron phthalocyanine (FePc) systems on gold electrodes modified by self-assembled monolayers (SAMs) is becoming an interesting strategy for obtaining electrocatalytic molecular building blocks for the oxygen reduction reaction (ORR). In this work, we have measured the conductance of pyridiniums axial ligands at the single molecule level using the scanning tunneling microscope-based break-junction method (STM-Break Junction) to study the role of the axial ligand on the activity of the self-assembled FePc systems on a gold electrode surface. The electron-pulling effect of pyridinium axial ligands is known to increase the electrocatalytic activity of FePc for the oxygen reduction reaction (ORR). We have used these systems as a platform for carrying out a comparative study for understanding the real influence of the proximal axial ligands. Further, these ligands act as molecular wires between the gold electrode surface and the FePc molecule. The pyridinium molecules were synthesized following a series of structural variations using a basic molecular backbone. From conductance measurements obtained for each pyridinium molecule, it was possible to establish that electron transport through each pyridinium does not influence the activity of FePc for ORR in alkaline media. In addition, the DFT calculations shows that the axial ligand in FePc modifies its catalytic activity by decreasing the binding energy of O-2 to the Fe site. (C) 2019 Elsevier Ltd. All rights reserved.