The Use of Conducting Diamond in Electrochemistry

Boron incorporated during a chemical vapor deposition (CVD) process is now proving to be the most popular means of imparting electrical conductivity on the diamond lattice for use in electrochemistry, both from a research perspective and commercially, for reasons that will be discussed later. There have been many reviews since 1983, both in journals [2-9] and books [10] on the use of diamonds in electrochemistry. This chapter aims to review the field and provide a comprehensive discussion on the current understanding of the fundamental factors controlling the response of boron-doped diamond (BDD) electrodes. Latest developments (as of 2014) are also highlighted. 

Edited by Richard C. Alkire, Philip N. Bartlett and Jacek LipkowskL 

High electronic mobility 4500 cm V i s i (electron), 3800cm V l s i (hole) 

Growth of Synthetic Boron-Doped Diamond for Electrochemical Applications 

There are several challenges associated with the synthesis of BDD suitable for electrochemistry. Since diamond is a semiconductor with exceptional properties, precise control of dopant impurities and extended defects is required to dope the diamond lattice with sufficient boron to make the material conduct. However, as the boron levels increase, it can be harder to maintain crystallinity and control the amount of nondiamond carbon (NDC) both within crystal defects and at grain boundaries. While NDC can increase material conductivity, it is be detrimental to a diamond electrochemist, as the widely recognized electrochemical properties of BDD (wide solvent window, low background currents, reduced susceptibility to electrode fouling, corrosion resistance) are impaired and the electrochemical response becomes more akin to glassy carbon. If the presence of NDC is unaccounted for, electrical resistivity measurements will mislead the user into believing that there is more boron than actually present in the matrix. 

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In 1983, Japanese scientists at the Institute of Physical and Chemical Research (RIKEN) in Saitama reported the use of ion-implanted diamond as an electrochemical electrode [l]. Their electrode had a wider potential window in the cathodic direction and lower background than glassy carbon. However, their diamond was made conductive by ion implantation of Zn, which resulted in a damaged surface. Although this was the first report on diamond electrochemistry, it did not lead to other work. 

Highly boron-doped diamond films, which have been widely studied in electrochemistry, can be grown by chemical vapor deposition (CVD) and are electrically conductive. Different electrochemical properties of boron-doped diamond films have been studied, such as reactivity [133] and electronic structure [134]. Different characterization techniques have been used to study the electrochemistry of diamond, such as scanning electron microscopy [123, 135] and Raman spectroscopy [125,136]. 

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