基于二甲基亚砜（DMSO）的电解液中金电极表面上的氧还原反应的原位原子力显微镜（AFM）研究,The Journal of Physical Chemistry C

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基于二甲基亚砜（DMSO）的电解液中金电极表面上的氧还原反应的原位原子力显微镜（AFM）研究
The Journal of Physical Chemistry C ( IF 3.3 ) Pub Date : 2016-10-26 00:00:00 , DOI: 10.1021/acs.jpcc.6b08718
Can Liu ₁ , Shen Ye ₁

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在本研究中，使用电化学原子力显微镜（EC-AFM）研究了基于二甲基亚砜（DMSO）的电解液中氧还原（ORR）和氧释放反应（OER）过程中金电极的形貌变化。）借助振动光谱测量。EC-AFM直接证实了ORR产物在电极表面的生长，该产物主要归因于过氧化锂（Li ₂ O ₂）。发现溶液中的水浓度显着影响ORR产物的形态。各向异性Li ₂ O ₂的生长已证实金电极表面上的颗粒是电化学过程。没有证据支持歧化生长机制。这些ORR产物在随后的OER过程中以高达4.4 V（vs Li ⁺ / Li）的电位完全分解，比通过表面增强拉曼光谱（SERS）测量确定的电位更强。结合红外吸收光谱和SERS测量，我们提出Li ₂ O ₂的氧化分解沉积首先在其与金电极表面的界面处发生，而其余颗粒的沉积则在较高的超电势下发生。相反，当溶液中包含四硫富富瓦烯（TTF）时，ORR沉积物可以在低至3.6 V的电位下完全分解。我们通过EC-AFM证实，电化学生成的TTF ⁺可以通过均相氧化机制在较低电势下介导Li ₂ O ₂的分解。

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In Situ Atomic Force Microscopy (AFM) Study of Oxygen Reduction Reaction on a Gold Electrode Surface in a Dimethyl Sulfoxide (DMSO)-Based Electrolyte Solution

In the present study, the morphological changes on a gold electrode during the oxygen reduction (ORR) and oxygen evolution reaction (OER) processes in a dimethyl sulfoxide (DMSO)-based electrolyte solution were investigated using an electrochemical atomic force microscope (EC-AFM) with the help of vibrational spectroscopy measurements. The growth of the ORR products on the electrode surface, which was mainly assigned to lithium peroxide (Li₂O₂), was directly confirmed by the EC-AFM. It was found that the water concentration in the solution significantly affects the morphology of the ORR products. The growth of anisotropic Li₂O₂ particles on the gold electrode surface has been confirmed to be an electrochemical process. No evidence was found to support the disproportionation growth mechanism. These ORR products were fully decomposed at a potential as high as 4.4 V (vs Li⁺/Li) in the subsequent OER process, more positive than that determined by a surface-enhanced Raman spectroscopy (SERS) measurement. Combined with infrared absorption spectroscopy and SERS measurements, we propose that the oxidation decomposition of the Li₂O₂ deposits first occurs at its interface with the gold electrode surface, while that of the remaining particles takes place at a higher overpotential. On the contrary, the ORR deposits could be fully decomposed at a potential as low as 3.6 V when tetrathiafulvalene (TTF) was included in the solution. We confirmed by EC-AFM that the electrochemically generated TTF⁺ can mediate the decomposition of the Li₂O₂ at a lower potential through a homogeneous oxidation mechanism.

更新日期：2016-10-26

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