Simultaneous Opto- and Spectro-Electrochemistry – Reactions of Individual Nanoparticles Uncovered by Dark-Field Microscopy,Journal of the American Chemical Society

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Simultaneous Opto- and Spectro-Electrochemistry – Reactions of Individual Nanoparticles Uncovered by Dark-Field Microscopy
Journal of the American Chemical Society ( IF 14.4 ) Pub Date : 2018-07-11 , DOI: 10.1021/jacs.8b02367
Kevin Wonner ₁ , Mathies V. Evers ₁ , Kristina Tschulik ₁

Affiliation

Despite the frequent use of silver nanoparticles in consumer products and medical treatments, their reactivity and degradation in aqueous suspensions are still under debate. Here we elucidate this reactivity by an in situ opto- and spectro-electrochemical approach. Using dark-field microscopy coupled to a spectrophotometer and to an electrochemical cell, redox reactions of individual silver nanoparticles are studied in the presence of chloride. The intensity and spectral position of the plasmon resonance of an individual particle are tracked simultaneously in real time during cyclic voltammetry. They both change almost instantaneously with the detected current in a chemically reversible way. Thus, it is evidenced that the intensity decrease of the optical signal at the silver peak position is caused by the reversible formation of silver chloride and not by dissolution of silver. Moreover, at large positive potentials, further transformation to silver oxide or chlorite is revealed spectroscopically, although the electrochemical current is hidden by water and chloride oxidation. Thus, the combination of electrochemistry with dark-field microscopy and hyperspectral imaging is introduced as a new tool for real-time analysis of (electro-)chemical reactions of nanoparticles on a single-entity level.

中文翻译：

同时进行光化学和光谱电化学——暗场显微镜发现的单个纳米粒子的反应

尽管银纳米粒子在消费品和医疗中经常使用，但它们在水悬浮液中的反应性和降解性仍存在争议。在这里，我们通过原位光和光谱电化学方法阐明了这种反应性。使用与分光光度计和电化学电池耦合的暗场显微镜，在氯化物存在下研究单个银纳米粒子的氧化还原反应。在循环伏安法期间，可以实时同时跟踪单个粒子的等离子体共振的强度和光谱位置。它们都以化学可逆的方式随着检测到的电流几乎瞬间发生变化。因此，有证据表明，银峰位置的光信号强度降低是由氯化银的可逆形成引起的，而不是由银的溶解引起的。此外，在较大的正电位下，光谱学显示出进一步转化为氧化银或亚氯酸盐，尽管电化学电流被水和氯化物氧化所掩盖。因此，电化学与暗场显微镜和高光谱成像的结合被引入作为在单个实体水平上实时分析纳米粒子的（电化学）化学反应的新工具。

更新日期：2018-07-11

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