Boron doped diamond

The past two decades have seen the establishment of a very extensive literature on the application of boron-doped diamond electrodes for the decoloration and the removal of COD and TOC from effluents, the disinfection and quality improvement of water, and the complete oxidation of particular organic molecules [26, 38, 39, 71-75]. There can be no doubt that boron-doped diamond anodes allow the effective killing of microorganisms and the complete oxidation of a wide range of organic compounds to carbon dioxide (and other inorganic fragments). Both direct and indirect mechanisms have been invoked. The direct mechanisms involve electron transfer and oxidation via weakly adsorbed OH radicals, while the indirect mechanisms have seen a role for solution-free OH radicals, ozone, sulfate radicals, or chlorine compounds if suitable anions are present or added. Indirect routes via ozone [20, 21] and sulfate radicals [40, 74, 76-78] can, of course, become dominant with appropriate selection of the conditions. This literature has been extensively reviewed and the interested reader is referred to these reviews [26, 38, 39, 71-75]. 

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A boron-doped diamond electrode was used as prepared. 

An electrochemically oxidized boron-doped diamond electrode was used. The observed rates were concentration-dependent. 

Highly boron doped diamond film supplied by Naval Research Laboratory, USA. 

Yagi I, Ishida T, et al. 2004. Electrocatal)tic reduction of oxygen to water at Au nanoclusters vacuum-evaporated on boron-doped diamond in acidic solution. Electrochem Commun 6 773-779. 

Finally, the presence of ultrasound in the electrodeposition of metals can produce both massive metal and metal colloid [75]. The reduction of AuCLt- at polycrystalline boron-doped diamond electrodes follows two pathways forming... 

Holt KB, Sabin G, Compton RG et al (2002) Reduction of tetrachloroaureate(III) at boron-doped diamond electrodes gold deposition versus gold colloid formation. Electroanalysis 14 797-803... 

Saterlay AJ, Wilkins SJ, Holt KB et al (2001) Lead dioxide deposition and electrocalysis at highly boron-doped diamond electrodes in the presence of ultrasound. J Electrochem Soc 148 E66-E72... 

Saez V, Gonzalez-Garcia J, Kulandainathan MA et al (2007) Electro-deposition and stripping of catalytically iron metal nanoparticles at boron-doped diamond electrodes. Electrochem Commun 9 1127-1133... 

Couto et al. [11] developed a flow injection system with potentiometric detection for determination of TC, OTC, and CTC in pharmaceutical products. A homogeneous crystalline CuS/Ag2S double membrane tubular electrode was used to monitor the Cu(II) decrease due to its complexation with OTC. The system allows OTC determination within a 49.1 1.9 x 103 ppm and a precision better than 0.4%. A flow injection method for the assay of OTC, TC, and CTC in pharmaceutical formulations was also developed by Wangfuengkanagul et al. [12] using electrochemical detection at anodized boron-doped diamond thin-film electrode. The detection limit was found to be 10 nM (signal-to-noise ratio = 3). 

Wangfuengkanagul and Chailapakul [9] described the electroanalysis of ( -penicillamine at a boron-doped diamond thin film (BDD) electrode using cyclic voltammetry. The BDD electrode exhibited a well-resolved and irreversible oxidation voltammogram, and provided a linear dynamic range from 0.5 to 10 mM with a detection limit of 25 pM in voltammetric measurement. In addition, penicillamine has been studied by hydrodynamic voltammetry and flow injection analysis with amperometric detection using the BDD electrode. 

In the case of boron impurities a complementary situation occurs. Boron has only three outer bonding electrons instead of the four found on carbon. Each boron impurity atom occupies a carbon position, forming Be, which results in the creation of a set of new acceptor energy levels just 0.64 x 10 19 J (0.4 eV) above the valence band. The transition of an electron from the valence band to this acceptor level has an absorption peak in the infrared, but the high-energy tail of the absorption band spills into the red at 700 nm. The boron-doped diamonds therefore absorb some red light and leave the gemstone with an overall blue color. 

J. Stotter, J. Zak, Z. Behier, Y. Show, G.M. Swain, Optical and electrochemical properties of optically transparent, boron-doped diamond thin films deposited on quartz, Anal. Chem., vol. 74, p.5924, 2002. 

Figure4.2 Field emission SEM image of a monolayer ofTi02 NPs adsorbed onto a highly polished boron-doped diamond electrode. From reference [38] with permission.

Marken and coworkers examined Ti02 NPs in various types of interfadal assemblies [38, 40, 57, 58]. In their first study, commerdally available 6-nm diameter Ti02 NPs were directly adsorbed onto polished boron-doped diamond electrodes from acidic aqueous solutions containing the Ti02 sol [38]. Using field emission SEM and STM, they observed relatively uniform adsorption of the Ti02 NPs and small... 

The boron-doped diamond (BDD) thin films are particifiarly attractive for electro analytical applications due to their unique characteristics, including... 

Wang, J., G. Chen, M. Chatrathi, K. Shin, and A. Fujishima. Microchip capillary electrophoresis coupled with a boron-doped diamond electrode-based electrochemical detector. Anal. Chem. 75, 935-939 (2003). 

Sires I., P.L. Cabot, F. CenteUas, J.A. Garrido, R.M. Rodriguez, C. Arias, and E. Brillas (2006). Electrochemical degradation of clofibric acid in water by anodic oxidation Comparative study with platinum and boron-doped diamond electrodes. Electrochimica Acta 52 75-85. 

The electrode material for electrofluo-rination processes is important, and new materials with high conductivity but chemically inert surface characteristics are desirable. Materials such as Ni, Monel, or HastaUoy are commonly employed [46] and the use of Pt has been pioneered by Schmidt [47]. Boron-doped diamond is a novel electrode material with a chemically highly inert surface suitable for... 

The suitability of boron-doped diamond as anode material for the generation of aggressive reagents, such as bromine, has been investigated. Vinokur et al. reported that the electron transfer at boron-doped diamond electrodes is strongly affected by the nature of the electrode process. Irmer-sphere processes such as the bromine evolution from bromide seem to be Id-netically slow, [73,120] in particular, when occurring positive of a potential of approximately —0.05 V vs. SCE. This is currently limiting possible wider applications of boron-doped diamond electrode materials. 

Electrodeposition on boron-doped diamond has pointed to progressive growth mechanism, as confirmed by chronoam-perometric transients and ex situ AFM images [ 312]. At lower concentrations, lead ions are deposited directly on the diamond substrate, while at higher concentrations, deposits overlap and further deposition occurs on lead. At higher temperatures, the size of the nuclei is bigger. 

Deposition of mercury at boron-doped diamond (BDD) and platinum electrodes has also been studied [33]. Deposition and oxidation of mercury was performed by cyclic voltammetry from the solution of 1 mM Hg2 ( 104)2 in 1 M Na l04. In order to learn more about this deposition, it was carried out also under chronoamperometric conditions. The results obtained are shown in Fig. 2 in the form of dimensionless current-time transients. Experimental curves obtained at two different overpotentials were compared with the theoretical curves calculated for instantaneous and progressive nucleation. A good agreement of experimental plots with the instantaneous nucleation mechanism was... 

Fig. 2 Comparison of the experimental dimensionless current-time transients for electrodeposition of mercury onto boron-doped diamond electrode with the theoretical transients for instantaneous (upper curve) and progressive (lower curve) nucleation overpotentials (x) 0.862 V and ( ) 0.903 V (from Ref 33).

Sopchak D, Miller B, Avygal Y, Kalish R (2002) Rotating ring-disk electrode studies of the oxidation of p-methoxyphenol and hydroquinone at boron-doped diamond electrodes. J. Electroanal Chem 538 39-45. 

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