References
1. M. Iwaki, S. Sato, K. Takahashi and H. Sakairi, Nucl. Instrum. Methods Phys. Res., 209 1983 1129. 2. Y. V. Pleskov, A. Ya. Sakharova, M. Krotova, L. L. Bouilov and B. V. Spitsyn, J. Electroanal. Chem., 228 1987 19. 3. K. Patel, K. Hashimoto and A. Fujishima, Denki Kagaku, 60 1992 659. 4. L. Boonma, T. Yano, D. A. Tryk, K. Hashimoto and A. Fujishima, J. Electrochem. Soc, 144 1997 L142. 5. T. N. Rao, D. A. Tryk, K. Hashimoto and A. Fujishima, J. Electrochem. Soc., 146 1999 680. 6. R. Tenne, K....
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1. M.E. Johll, D.G. Williams and D.C. Johnson, Electroanalysis, 9 1997 1397. 2. D.G. Davis and E. Bianco, Analyst Cambridge, UK , 119 1994 309. 3. R. Guidelli, F. Pergola and G. Rossi, Anal. Chem., 44 1972 745. 4. N.L. Weinberg and H.R. Weinberg, Chem. Rev., 68 1968 449. 5. I.H. Yeo and D.C. Johnson, J. Electroanal. Chem., 495 2001 110. 6. D.T. Fagan, I.F. Hu and T. Kuwana, Anal. Chem., 57 1985 2759. 7. J.W. Strojek, M.C. Granger, T. Dallas, M.W. Holtz and G.M. Swain, Anal. Chem., 68 1996 2031....
Electrochemical Detection of Nickel Ions in Solution
Electroless nickel EN deposits have been used commercially in many diverse fields, such as the aerospace, automotive, electronics, machinery, oil and gas production and valve industries 20,21 . The detection of nickel in EN deposition baths is very important. The present study includes the analysis of Ni ions based on cathodic stripping of electrogenerated Ni III to Ni II . Initially, the electrodeposition of nickel ions was carried out at -2.0 V under hydrodynamic conditions, and the deposited...
Application of Diamond Electrodes for Water Disinfection
Tsuneto Furuta, Phylippe Rychen, Hozumi Tanaka, Laurent Pupunat, Werner Haenni and Yoshinori Nishiki With regard to traditional water treatment technologies and their markets, new solutions should be found in order to settle current and future problems, as well as to improve the economical and ecological situations of several leading-edge processes. Electrochemical processes, such as electrodialysis, electrowinning, electrodeionization, electroflotation, electroflocculation and others, appear...
Detection of biogenic amines
Biogenic amines act as important chemical messengers in biological systems, and they are also present in several food products. Therefore, the detection of these biogenic amines is important for monitoring both the freshness of food and also elevated cerebral and urinary concentrations. Higher levels of polyamines are found in cancer patients 28 . Abnormalities in the concentrations of serotonin 5-hydroxytryptamine, or 5HT , and other biogenic amines indicate psychiatric disorders 29 ....
I At
chemical oxygen demand at time t mol O2 dm'3 ,' COD t At chemical oxygen demand at time t At mol O2 dm'3 ,' I current A F Faraday's constant 26.8 Ah V volume of electrolyte dm3 and At time interval of COD measurement h . Table 20.2. Equations describing COD and ICE evolution during oxidation at a BDD electrode. Vr reservoir volume m3 , k m masstransfer coefficient m s'1 , A electrode area m2 , COD initial chemical oxygen demand mol O2 m'3 , a i i iim. Table 20.2. Equations describing COD and...
Combined Methods Electrochemical Chemical methods
Although there are other examples of combined methods, such as photochemical-chemical, which have already been mentioned briefly, as in the case of the photochemical-chemical attachment of DNA strands, we shall focus on that of electrochemical-chemical method. This combined approach has been used recently to attach a protein to the diamond surface 59 , using first electrochemical oxidation to produce hydroxyl groups, followed by esterification to attach biotin, with subsequent attachment of...
CurrentVoltage Curves
It is known that one of the characteristic features of semiconductor metal contacts is the rectification of electric current. The asymmetry of current voltage curves at a semiconductor metal contact is quite pronounced the direct current passing the contact can be rather large, while the reverse blocking current is very small. The current voltage characteristics at some ideal semiconductor electrodes do follow this law e.g., anodic dissolution of n-type germanium, etc. 7 , For ptype boron-doped...
Preparation of powerful oxidants
The unique properties of BDD electrodes high anodic stability and high oxygen overpotential can allow the production of powerful oxidants, with high redox potential. Two examples have been treated below a The oxidation of Ag I to Ag II in concentrated HNO3 E0 1.98 V vs. SHE . This redox couple can be used as mediator in the partial oxidation of organic compounds applications in synthesis , or for the electrochemical combustion of organic compounds applications in wastewater treatment . b The...
Carbonyl Groups on the Diamond Surface
It is expected that carbonyl groups C 0 and ether groups OOC are generated on the diamond 100 surface ll , and hydroxyl groups C-OH are generated on the ill surface by these surface oxidation methods Fig. 10.7 . Surface carbonyl groups existing on the GC electrode catalyze the redox reaction of Fe 2 3 12-14 . It is possible that similar catalytic effects could occur with the oxidized diamond electrode surfaces. Therefore, to probe for the existence of carbonyl groups and their effects on the Fe...
Differential pulse voltammetric DPV study
The DPV responses of the BDD electrode for 2.3 jiM Ni ions contained in 0.1 M NaOH 0.1 M NH4NO3 alkaline solution showed a sharp signal at 0.6 V vs Ag AgCl, which was attributed to the reduction of Ni III to Ni II Fig. 17.5 . However, it is noted that the sensitivity was higher under rotating conditions than stirred conditions Fig. 17.5 , which may be due to enhanced mass transfer in the former method see below . After the detection of both stock and sample solutions, the nickel hydroxide layer...
Professor Akira Fujishima
Professor Fujishima was born in 1942 in Tokyo. He received his Ph. D. in Applied Chemistry at the University of Tokyo in 1971. He taught at Kanagawa University for four years and then moved to the University of Tokyo, where he became a Professor in 1986. In 2003, he retired from this position and took on the position of Chairman at the Kanagawa Academy of Science and Technology. His main interests are in photocatalysis, photoelectrochemistry and diamond electrochemistry. Kanagawa Academy of...
Wide Potential Window in Aqueous Solutions
It is well stated that the hydrogen-terminated surface of as-grown diamond is not favorable for adsorption. This is why conductive diamond electrodes exhibit very high overpotentials for hydrogen, oxygen and halide evolution, leading to a wide potential window in which the background current is very low 14-16 . Although the width of this window is dependent to some extent on the quality of the film see ref. 17 and references therein , potential values as high as ca. 2.15 V vs. SCE are usually...
Conclusions Cwu
The highly attractive characteristics of conductive diamond electrodes continue to bring attention. Recently, it has also become clear that the possibilities for chemical modification can take advantage of these fundamental characteristics and build upon them, imparting novel selectivity and catalytic activity. The possible applications are as diverse as those for all other types of electrodes, because diamond can be a useful substrate for all. Moreover, all of the modification techniques that...
Electroanalysis of Sodium Thiosulfate [
Sodium thiosulfate, also called hypo, is an important compound that finds application in chemical and biological fields, especially in the photographic industry. It is becoming a prime pollutant in that industry, and it is therefore very important to detect its presence in waste materials. The electrochemical method used at present involves amperometric analysis using glassy carbon GC electrodes modified with either cobalt or nickel hexacyanoferrate as the electrode material 14,15 , On the...
Potential V vs SCE
Fig. 12.1. Cyclic voltammograms at GC and BDD electrodes in air-saturated 0.1 M phosphate buffer containing 50 jiM NADH at a potential sweep rate of 20 mV s1. The sensitivity of the diamond electrode for the determination of NADH was demonstrated by the use of amperometry at 0.58 V vs. SCE. The limit of detection was 10 nM signal-to-noise S N ratio 3 . The responses at BDD electrodes remained stable for three monthswhile the electrode was exposed to the laboratory atmosphere. The diamond...
Nanolithographic Modification of Diamond with AFM Techniques
Differences in the surface conductivity with surface termination of diamond can be applied to the nanolithographic modification of diamond surfaces by use of atomic force microscopy AFM techniques 5052 . Modification can be carried out by applying an electrical bias to the sample surface via a conductive cantilever tip, e.g., Au-coated Si Fig. 8.8 . Surface modification using such an AFM technique is relatively general, and has been achieved for semiconductor materials such as Si 53 , GaAs 54...
Electrolysis of ultrapure water
For water electrolysis, the self-standing perforated diamond electrode was used as the anode, being set as shown in Fig. 24.1 a . Platinum mesh 55 mesh, Nilaco Co., Japan was used as the cathode. Nafions films DuPont, USA were used as the solid-state polymer electrolyte membrane to separate the anode and cathode compartments, to which the anode and cathode adhered firmly and uniformly. Ultrapure water purified by a Milli-Q system, Millipore Japan, Ltd. was continuously supplied into each...
Contact Angle of Water Droplets
One of the obvious differences between hydrogen-terminated diamond and oxygenated diamond can be seen in the values of the water contact angle. The contact angle of a sample depends on the polarity of the functional groups on the sample surface. The contact angle for as-deposited diamond of about 90 decreases to nearly 0 after surface oxidation by oxygen plasma treatment for 1 min. After the other surface oxidation methods, e.g., oxygen annealing and electrochemical oxidation, the contact...
Rotating disk electrodes
Rotating disk electrodes have been used for many years in electrochemistry in order to enhance and better control the hydrodynamics 41 . The use of such electrodes in ASV analysis has also been pursued for a number of years, because it can lead to both higher sensitivity and higher precision. However, during the stripping, the electrode rotation can also help to improve the sensitivity by enhancing the mass transport of the oxidized metal ions into the bulk solution. Here, the stripped metal...
Semiconducting Diamond Electrodes Doping of diamond
Boron-doped diamond has been widely studied, and some of the properties of relevance to electrochemistry have been reviewed 20, 42, 43 , Substitutional boron at low concentrations gives an acceptor level at 0.37 eV above the valence band 44 , At very high concentrations of boron gt 1020 cm 3 , a dopant band is formed 4449 . The resistivity ranges from about 104 Q cm at a boron concentration of 1018 cm 3 to tenths and thousandths of an Q cm for boron concentrations of the order of 1021 cm'3. At...
Electrochemical potential windows in nonaqueous Electrolytes
Fig. 6.1 shows the cyclic voltammograms CVs obtained for an as-deposited diamond electrode in several non-aqueous electrolytes and an aqueous electrolyte l M H2SO4 . In this study, the working potential window is defined as the range between the potentials at which the anodic and cathodic current densities reach 2 mA cm2 l . The non-aqueous electrolytes examined exhibit potential windows Fig. 6.1 a - e that are 1.5-2.5 times wider than that obtained in the aqueous acid electrolyte Fig. 6.1 . In...
Wide Working Potential Window
A clean polycrystalline diamond film with negligible sp2 carbon impurities can exhibit an electrochemical potential window as large as 2.5 V, covering wide regions on both the negative and positive potential sides in aqueous solutions due to high overpotentials for the oxygen and hydrogen evolution reactions l . The high overpotentials for oxygen and hydrogen are not clearly understood yet, although some reasonable explanations have been suggested 2 , This topic has also already been treated to...
Fabrication of Nanostructured Diamond
19.2.1. Template synthesis of nanostructured materials There are numerous chemical methods for preparing nanomaterials 2, 3 . A number of researchers have been studying a method termed template synthesis 3 . Traditionally, this method has entailed synthesizing the nanoordered structure of a desired compounds or material by use of a nanoscale template. Kensuke Honda e-mail khonda yamaguchi-u.ac.jp Recently, the template method has been used with the pores in a microporous solid as a nanoscopic...
Hydroxyl Groups on the Diamond Surface
In addition to confirming the presence of carbonyl groups, the redox behavior of Fe CN 6 4 3' at the APTES-treated diamond electrodes was observed in order to confirm the presence of hydroxyl groups. The APTES treatment significantly decreased the AEp value for the oxygenated diamond electrodes to ca. 150 mV Table 3 16 . The increase in the redox reaction rate for Fe CN e 4' 3' was presumably caused by the electrostatic attraction 17 between the positively charged protonated amino groups of the...
References Qgs
1. J. Weiss, Trans. Faraday Soc., 31 1935 668. 2. P. C. Foller and C. W. Tobias, J. Electrochem. Soc., 129 1982 506. 3. S. Stucki, G. Theis, R. Kotz, H. Devantay and H. J. Christen, J. Electrochem. Soc., 132 1985 367. 4. P. Tatapudi and J. M. Fenton, J. Electrochem. Soc., 141 1994 1174. 5. N. Katuki, S. Wakita, Y. Nishiki, T. Shimamune, Y. Akiba and M. Fig. 24.8. Photograph of an ozone-water generator with a self-standing perforated diamond electrode. Iida, Jpn. J. Appl. Phys., 36 1997 L260. 6....
Properties of Diamond Electrodes Wide potential window
The surfaces of as-grown chemical vapor deposited diamond electrodes that have been cooled to room temperature under atomic hydrogen are terminated with hydrogen. These surfaces are hydrophobic and not attractive for adsorption. Therefore, electrode reactions that involve adsorbed intermediates may be strongly inhibited on diamond. One result, initially attributed to the hydrogen termination, is a very wide potential range over which the rate of water electrolysis is negligible 12-14 . Fig. 3.1...