Department of Chemistry, University of Warwick, Coventry, UKCV4 7AL.
Chem Commun (Camb). 2009 Dec 7(45):6886-901. doi: 10.1039/b909734a. Epub 2009 Sep 23.
Electrochemistry at carbon nanotubes (CNTs) is a large and growing field, but one in which there is still uncertainty about the fundamental activity of CNTs as electrode materials. On the one hand, there are many reports which focus on the favourable electrochemical properties of CNT electrodes, such as enhanced detection sensitivity, electrocatalytic effects and reduced fouling. On the other hand, other studies suggest that CNTs may be no more electroactive than graphitic powder. Furthermore, it has been proposed that the catalytic nanoparticles from which CNTs are formed may dominate the electrochemical characteristics in some instances. A considerable body of the literature presumes that the CNT sidewall is inert and that edge-plane-graphite-like open ends and defect sites are responsible for the electron transfer activity observed. In contrast, studies of well characterised single-walled nanotube (SWNT) electrodes, either as individual tubes or as two-dimensional networks, suggest sidewall activity. This review highlights how the various discrepancies in CNT electrochemistry may have arisen, by taking a historical view of the field and identifying crucial issues that still need to be solved. When assessing the behaviour of CNT electrodes, it is vitally important that careful consideration is given to the type of CNT used (SWNT or multi-walled), the quality of the material (presence of impurities), the effect of chemical processing steps in the fabrication of electrodes and the experimental arrangements adopted. Understanding these key features is an essential requirement to develop a fundamental understanding of CNT electrochemistry, to allow a wide range of electroanalytical applications, and to move the field forward rationally. As part of this process, high resolution electrochemical and electrical imaging techniques are expected to play a significant role in the future, as well as theoretical developments which examine the fundamentals of electron transfer at different types of CNTs and their characteristic surface sites.
电化学在碳纳米管（CNTs）是一个庞大且不断发展的领域，但对于 CNT 作为电极材料的基本活性仍存在不确定性。一方面，有许多报道集中在 CNT 电极的有利电化学性质上，例如增强的检测灵敏度、电催化效应和减少的污垢。另一方面，其他研究表明，CNTs 的电化学活性可能并不比石墨粉末高。此外，有人提出，CNTs 形成的催化纳米颗粒可能在某些情况下主导电化学特性。大量文献假设 CNT 的侧壁是惰性的，而边缘平面类似石墨的开口端和缺陷位负责观察到的电子转移活性。相比之下，对经过良好表征的单壁碳纳米管（SWNT）电极的研究，无论是作为单个管还是二维网络，都表明侧壁具有活性。通过对该领域的历史回顾，并确定仍需解决的关键问题，本综述强调了 CNT 电化学中的各种差异是如何产生的。在评估 CNT 电极的行为时，至关重要的是要仔细考虑所使用的 CNT 类型（SWNT 或多壁）、材料的质量（是否存在杂质）、电极制造过程中化学处理步骤的影响以及所采用的实验安排。了解这些关键特征是发展对 CNT 电化学的基本理解、允许广泛的电分析应用以及合理推动该领域前进的必要条件。作为这个过程的一部分，高分辨率电化学和电学成像技术有望在未来发挥重要作用，以及理论发展，这些理论研究考察了不同类型的 CNT 及其特征表面位的电子转移的基本原理。
