Adsorption-Coupled Electron-Transfer Mode of Scanning Electrochemical Microscopy: Voltammetric Simulation
Adsorption-Coupled Electron-Transfer Mode of Scanning Electrochemical Microscopy: Voltammetric Simulation
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DOI：
10.1016/j.electacta.2023.141973
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发表时间：
2023-01
影响因子：
6.6
通讯作者：
Donald C. Janda;K. Barma;Moghitha Parandhaman;Xindi Sun;Kevin C. Leonard;S. Amemiya
中科院分区：
文献类型：
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作者：
Donald C. Janda;K. Barma;Moghitha Parandhaman;Xindi Sun;Kevin C. Leonard;S. Amemiya
在许多重要的电极反应中，电子转移和氧化还原活性分子的特异性吸附之间的耦合是普遍存在的，也是至关重要的。实际上，吸附耦合电子转移（ACET）反应在电沉积和电插层中产生不可逆吸附产物，在电催化和光电催化中产生可逆吸附中间体。从根本上说，由于协同机制和非协同机制并存，ACET反应是高度复杂的。本文从理论上模拟了扫描电化学显微镜（SECM）的ACET模式，以实验和定量研究ACET反应的动力学和机理。具体来说，在衬底上的ACET反应是伏安驱动的，并在针尖上进行安心监测，以模拟针尖电流与循环衬底电位的伏安图。在负ACET模式下，可逆吸附的反应物通过协同或非协同机理产生不可逆吸附物。此外，在正ACET或正反馈模式下，非吸附反应物分别通过协同或非协同机制产生可逆吸附，并辅之以两种机制的底物生成/尖端收集模式。我们预测，当可逆吸附步骤得到动力学控制时，可以确定ACET的机理。通过对各种底物反应的分析，证明了该模型的有效性和适用性。这些反应包括氢电催化、金属电沉积、锂电插层、金属氧化物的类乙酰形成，甚至导电聚合物薄膜与离子转移耦合的氧化还原反应。强大的ACET模式将补充基于预成型吸附物定量的表面询问模式。
The coupling between the electron transfer and specific adsorption of a redox-active molecule is ubiquitous and crucial in many important electrode reactions. Practically, adsorption-coupled electron-transfer (ACET) reactions generate irreversibly adsorbed products in electrodeposition and electrointercalation and reversibly adsorbed intermediates in electrocatalysis and photoelectrocatalysis. Fundamentally, ACET reactions are highly complex owing to the co-existence of concerted and non-concerted mechanisms. Herein, we model the ACET mode of scanning electrochemical microscopy (SECM) theoretically to experimentally and quantitatively investigate the dynamics and mechanism of ACET reactions. Specifically, an ACET reaction at the substrate is driven voltammetrically and monitored amperimentrically at the tip to simulate the voltammogram of the tip current versus the cycled substrate potential. In the negative ACET mode, irreversible adsorbates are produced from reversibly adsorbed reactants through the concerted or non-concerted mechanism. Moreover, reversible adsorbates are produced from non-adsorbing reactants through the concerted or non-concerted mechanism in the positive ACET or positive feedback mode, respectively, as complemented by the substrate generation/tip collection mode of both mechanisms. We predict that the ACET mechanism can be identified when a reversible adsorption step is kinetically controlled. The validity and application of our model are demonstrated by considering various substrate reactions reported previously. These reactions include hydrogen electrocatalysis, metal electrodeposition, lithium electrointercalation, the ACET-like formation of metal oxides, and even the redox reaction of a conducting polymer film coupled with ion transfer. The powerful ACET mode will complement the surface-interrogation mode based on the quantitation of preformed adsorbates.