The Influence of Doping Levels and Surface Termination on the Electrochemistry of Polycrystalline Diamond

Abstract

The influence of surface chemistry and boron doping density on the redox chemistry of Fe(CN) 3À=4À 6 at CVD polycrystalline diamond electrodes is considered. It is demonstrated that for this couple both the doping density and the surface chemistry are important in determining the rate of charge transfer at the electrode/electrolyte interface. For hydrogen terminated CVD diamond metallic electrochemical behavior is always observed, even at boron doping densities as low as 7 Â 10 18 cm À3. In contrast, the electrochemical behavior of oxygen terminated CVD diamond varies with doping density, a metallic response being observed at high doping density and semiconductor behavior at low doping density. It is shown that the results attained may be explained by a surface state mediated charge transfer mechanism, thus demonstrating the importance of controlling surface chemistry in electroanalytical applications of diamond.

Investigation on Electrochemically Cathodic Polarization of Boron-Doped Diamond Electrodes and Its Influence on Lead Ions Analysis

“…This might be a typical character of all BDD with low B-dopant. 21 Unlike 700 ppm BDD where no reduction peaks appeared in cases of cathodic pretreatment durations from 5 to 30 min, both 2500 and 8000 ppm BDD presented their redox peaks (Figure 4b and 4c), regardless of the polarization duration. To compare the influence of the applied cathodic pretreatments on the surface activity of BDDs, Figure 4d shows their peak-peak potential differences varying with the cathodic polarization duration.…”

“…In general, a high boron doping level always renders the BDD electrode highly conductive, 21,41 thereby promoting redox reactions occurring on its surface. Our tests on BDDs with boron doping level from 700, 2500 to 8000 ppm also confirmed this point.…”

“…[16][17][18][19][20] The change in surface carbon atom termination alters undoubtedly the kinetics of redox reactions occurring on the BDD surface due to a distinct difference in electronic structure and surface energy between H-terminated and O-terminated surface. [21][22][23] Therefore, in order to make full use of the merits of BDD electrodes, it is important to make the type of surface carbon termination of a BDD electrode match up with application purposes.The O-termination surface of a BDD presents high surface energy and positive electron affinity, 22,24-26 thereby favoring hydroxyl radicals ( · OH) formation during anodic oxidation.27 Thus, this feature has been widely used in oxidation degradation of organic pollutants in waste water. However, the O-termination is not suitable for electroanalysis because of its low electron transfer rate [28][29][30] and high surface pollution derived from its hydrophilicity.…”

“…[16][17][18][19][20] The change in surface carbon atom termination alters undoubtedly the kinetics of redox reactions occurring on the BDD surface due to a distinct difference in electronic structure and surface energy between H-terminated and O-terminated surface. [21][22][23] Therefore, in order to make full use of the merits of BDD electrodes, it is important to make the type of surface carbon termination of a BDD electrode match up with application purposes.…”

The Use of Conducting Diamond in Electrochemistry

“…Boron dopant density clearly plays a significant role in governing the electrochemical characteristics of the material [17,82]. The redox species of choice for characterizing a newly prepared BDD electrode or any carbon material used to be the ferri/ferrocyanide redox couple.…”