Single-Nanoparticle Electrochemistry through Immobilization and Collision.
Single-Nanoparticle Electrochemistry through Immobilization and Collision.
复制标题
通过固定和碰撞通过单纳米颗粒电化学。
DOI：
10.1021/acs.accounts.6b00334
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发表时间：
2016-11-15
影响因子：
18.3
通讯作者：
Zhang B
中科院分区：
文献类型：
--
作者：
Anderson TJ;Zhang B
金属纳米颗粒在基础电子转移研究、电化学传感和电化学表面增强拉曼光谱(SERS)等多种电化学应用中是重要的电极材料。金属纳米粒子由于具有高催化活性和较大的比表面积，近年来也被广泛应用于电催化过程中。由于金属纳米粒子的催化活性往往高度依赖于它们的尺寸、形状、表面配体等，因此检测和更好地了解粒子结构和功能之间的关系的方法对于开发更有效的催化体系是非常有用的。尽管在这一领域取得了长足的进展，但由于传统系综测量的局限性，在基于纳米粒子的电化学和电催化中，对结构-活性关系的理解仍然具有挑战性。其中一个主要问题是电催化反应的整体平均，这发生在大量大小和形状不同的纳米粒子上。此外，电化学响应也会受到系综本身的性质的很大影响，例如粒子间距。在结构良好的单个纳米粒子上直接测量电化学反应动力学的能力为许多重要领域开辟了新的可能性，包括纳米级电化学、电化学传感和纳米粒子电催化。当宏观电极置于含有氧化还原分子和金属纳米颗粒的溶液中时，当电极上存在合适的电位时，除了氧化还原反应外，纳米颗粒在电极表面还会发生随机碰撞和吸附。在颗粒比底物更具催化活性的特殊情况下，颗粒表面的法拉第信号可以被极大地放大，并且由于电极上吸附了许多颗粒，预计基线电流将稳定移动。采用超微电极(UME)作为记录电极，可以实现对单粒子事件的时间分辨。UME的使用不仅降低了碰撞频率，而且大大降低了基线噪声，从而使单次碰撞事件的分辨率清晰。近年来，单粒子碰撞迅速发展成为一种流行的电分析技术。或者，人们可以使用纳米电极固定单个纳米颗粒，以便在电化学和电催化中单独研究它们。纳米粒子的固定化还使人们能够获得相同粒子的详细结构信息，并为更全面地了解纳米粒子基电催化剂的结构与功能关系提供了巨大的潜力。本文总结了我们小组最近使用这两种方案进行的单金属纳米颗粒的电化学实验。
Metal nanoparticles are key electrode materials in a variety of electrochemical applications including basic electron-transfer study, electrochemical sensing, and electrochemical surface enhanced Raman spectroscopy (SERS). Metal nanoparticles have also been extensively applied to electrocatalytic processes in recent years due to their high catalytic activity and large surface areas. Because the catalytic activity of metal nanoparticle is often highly dependent on their size, shape, surface ligands, and so forth, methods for examining and better understanding the correlation between particle structure and function are of great utility in the development of more efficient catalytic systems. Despite considerable progress in this field, the understanding of the structure–activity relationships remains challenging in nanoparticle-based electrochemistry and electrocatalysis due to limitations associated with traditional ensemble measurements. One of the major issues is the ensemble averaging of the electrocatalytic response which occurs over a very large number of nanoparticles of various sizes and shapes. Additionally, the electrochemical response can also be greatly affected by properties of the ensemble itself, such as the particle spacing. The ability to directly measure kinetics of electrochemical reactions at structurally well-characterized single nanoparticles opens up new possibilities in many important areas including nanoscale electrochemistry, electrochemical sensing, and nanoparticle electrocatalysis. When a macroscopic electrode is placed in a solution containing redox molecules and metal nanoparticles, random collision and adsorption of nanoparticles occurs at the electrode surface in addition to redox reactions when a suitable potential is present on the electrode. In a special case where particles are catalytically more active than the substrate, the faradaic signals can be greatly amplified on particle surfaces and a steady shift in the baseline current would be expected due to many particles adsorbing on the electrode. Single particle events can be temporally resolved when an ultramicroelectrode (UME) is used as the recording electrode. The use of an UME not only reduces the collision frequency, but also greatly decreases baseline noise, thereby resulting in clear resolution of single collision events. Single particle collision has quickly grown into a popular electroanalytical technique in recent years. Alternatively, one can use nanoelectrodes to immobilize single nanoparticles so that they can be individually studied in electrochemistry and electrocatalysis. Nanoparticle immobilization also allows one to obtain detailed structural information on the same particles and offers enormous potential for developing more comprehensive understanding of the structure–function relationship in nanoparticle-based electrocatalysts. This Account summarizes recent electrochemical experiments of single metal nanoparticles which have been performed by our group using both of these schemes.
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