Jiang Dan, Sun Linlin, Liu Tao, Wang Wei
State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University , Nanjing 210093, China.
Anal Chem. 2017 Nov 7;89(21):11641-11647. doi: 10.1021/acs.analchem.7b03061. Epub 2017 Oct 18.
Electrochemical behaviors of Prussian blue (PB) have been intensively studied for decades because it not only serves as a model electro-active nanomaterial in fundamental electrochemistry but also a promising metal-ion storage electrode material for developing rechargeable batteries. Traditional electrochemical studies are mostly based on bulk materials, leading to an averaged property of billions of PB nanoparticles. In the present work, we employed surface plasmon resonance microscopy (SPRM) to resolve the optical cyclic voltammograms of single PB nanoparticles during electrochemical cycling. It was found that the electrochemical behavior of single PB nanoparticles nicely followed a classical thin-film electrochemistry theory. While kinetic controlled electron transfer was observed at slower scan rates, intraparticle diffusion of K ions began to take effect when the scan rate was higher than 60 mV/s. We further found that the electrochemical activity among individual PB nanoparticles was very heterogeneous and such a phenomenon has not been previously observed in the bulk measurements. The present work not only demonstrates the thin-film electrochemical feature of single electro-active nanomaterials for the first time, it also validates the applicability of SPRM technique to investigate a variety of metal ion-storage battery materials, with implications in both fundamental nanoelectrochemistry and electro-active materials for sensing and battery applications.
几十年来，普鲁士蓝（PB）的电化学行为一直受到深入研究，因为它不仅是基础电化学中的一种典型电活性纳米材料，而且是开发可充电电池的一种有前景的金属离子存储电极材料。传统的电化学研究大多基于块状材料，这导致了数十亿个PB纳米颗粒的平均性质。在本工作中，我们采用表面等离子体共振显微镜（SPRM）来解析单个PB纳米颗粒在电化学循环过程中的光学循环伏安图。结果发现，单个PB纳米颗粒的电化学行为很好地遵循经典的薄膜电化学理论。在较慢的扫描速率下观察到动力学控制的电子转移，而当扫描速率高于60 mV/s时，K离子的颗粒内扩散开始起作用。我们进一步发现，单个PB纳米颗粒之间的电化学活性非常不均匀，这种现象在块状测量中以前未曾观察到。本工作不仅首次证明了单个电活性纳米材料的薄膜电化学特性，还验证了SPRM技术在研究各种金属离子存储电池材料方面的适用性，这对基础纳米电化学以及用于传感和电池应用的电活性材料都有重要意义。
