Single Particle Electrochemical Oxidation of Polyvinylpyrrolidone-Capped Silver Nanospheres, Nanocubes, and Nanoplates in Potassium Nitrate and Potassium Hydroxide Solutions
Single Particle Electrochemical Oxidation of Polyvinylpyrrolidone-Capped Silver Nanospheres, Nanocubes, and Nanoplates in Potassium Nitrate and Potassium Hydroxide Solutions
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DOI：
10.1149/1945-7111/ac63f3
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发表时间：
2022-05-01
影响因子：
3.9
通讯作者：
Fritsch, Ingrid
中科院分区：
文献类型：
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作者：
Sikes, Jazlynn C.;Niyonshuti, Isabelle I.;Fritsch, Ingrid
研究了微盘电极上聚乙烯吡咯烷酮封端的银纳米颗粒的单颗粒电化学氧化与硝酸钾和氢氧化钾溶液中颗粒形状（球体、立方体和板）的函数关系。在硝酸钾中，需要极高的阳极电位（相对于 Ag/AgCl (3 M KCl) >= 1500 mV）才能实现氧化，而氢氧化钾则需要较低的阳极电位（相对于 Ag/AgCl（饱和 KCl）>= 900 mV）。氧化后，形成氧化银，很容易催化水氧化，产生尖峰阶跃电流响应。每个颗粒的尖峰持续时间用于探测颗粒形状对氧化机制的影响，并且在大过电势的硝酸盐溶液中比在氢氧化物溶液中短得多。电流尖峰的积分表明氧化为混合价复合物。在两种电解质中，银氧化速率很大程度上取决于纳米颗粒的银含量，而不是取决于形状的可变表面积。反映水氧化速率的台阶高度也比形状更能追踪银含量。在这些阳极条件下，在硝酸盐和氢氧化物溶液中，还比较了较少保护的柠檬酸盐封端颗粒对银氧化的反应性与聚合物封端颗粒的反应性。
Single particle electrochemical oxidation of polyvinylpyrrolidone-capped silver nanoparticles at a microdisk electrode is investigated as a function of particle shape (spheres, cubes, and plates) in potassium nitrate and potassium hydroxide solutions. In potassium nitrate, extreme anodic potentials (>= 1500 mV vs Ag/AgCl (3 M KCl)) are necessary to achieve oxidation, while lower anodic potentials are required in potassium hydroxide (>= 900 mV vs Ag/AgCl (saturated KCl)). Upon oxidation, silver oxide is formed, readily catalyzing water oxidation, producing a spike-step current response. The spike duration for each particle is used to probe effects of particle shape on the oxidation mechanism, and is substantially shorter in nitrate solution at the large overpotentials than in hydroxide solution. The integration of current spikes indicates oxidation to a mixed-valence complex. In both electrolytes, the rate of silver oxidation strongly depends on silver content of the nanoparticles, rather than the shape-dependent variable-surface area. The step height, which reflects rate of water oxidation, also tracks the silver content more so than shape. The reactivity of less-protected citrate-capped particles toward silver oxidation is also compared with that of the polymer-capped particles under these anodic conditions in the nitrate and hydroxide solutions.