Electrode glassy-carbon

FIGURE 4-10 The open-pore structure of reticulated vitreous carbon. 

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The purity of a sample of K3Fe(CN)6 was determined using linear-potential scan hydrodynamic voltammetry at a glassy carbon electrode using the method of external standards. The following data were obtained for a set of calibration standards. 

Eig. 7. CycHc voltammograms for the reduction of 1.0 mAf [2,2 -ethylene-bis(nitrilomethyHdyne)diphenolato]nickel(II) in dimethyl formamide at a glassy carbon electrode, in A, the absence, and B and C the presence of 2.0 and 5.0 mAf 6-iodo-l-phenyl-l-hexyne, respectively (14). 

Electrolysis on a glassy carbon electrode, DME. Bu4N BE4, 85% yield. ... 

The D.M.E. can with advantage be replaced by an S.M.D.E. (Section 16.8), and it is possible to use platinum, graphite, or glassy carbon electrodes, in which case the procedure should be termed voltammetry rather than polarography. 

The actual value varies slightly depending on the way the glassy carbon electrode was pretreated. 

An argon-sputtered glassy carbon electrode was used. 

Determined by direct electrochemistry at a glassy carbon electrode (cyclic, differential pulse, or square-wave voltammetry). 

Fig. 17. Cyclic voltammogram of the water-soluble Rieske fragment from the bci complex of Paracoccus denitrificans (ISFpd) at the nitric acid modified glassy carbon electrode. Protein concentration, 1 mg/ml in 50 mM NaCl, 10 mM MOPS, 5 mM EPPS, pH 7.3 T, 25°C scan rate, 10 mV/s. The cathodic (reducing branch, 7 < 0) and anodic (oxidizing branch, 7 > 0) peak potentisds Emd the resulting midpoint potential are indicated. SHE, standEU d hydrogen electrode.

Traore M, Moddo R, Vittori O (1988) Electrochemical behaviour of tellurium and silver teUuride at rotating glassy carbon electrode. Hectrochim Acta 33 991-996 Ngac N, Vittori O, Quarin G (1984) Voltammetrie and chronoamperometric studies of tellurium electrodeposition of glassy carbon and gold electrodes. J Electroanal Chem 167 227-235... 

Traore M, Moddo R, Vittori O (1988) Electrochemical behaviour of tellurium and silver telluride at rotating glassy carbon electrode. Electrochim Acta 33 991-996... 

Fang YM, Sun JJ, Wu AH, Su XL, Chen GN (2009) Catalytic electrogenerated chemiluminescence and nitrate reduction at CdS nanotubes modified glassy carbon electrode. Langmuir 25 555-560... 

Glassy carbon electrodes polished with alumina and sonicated under clean conditions show activation for the ferrl-/ ferro-cyanlde couple and the oxidation of ascorbic acid. Heterogeneous rate constants for the ferrl-/ ferro-cyanlde couple are dependent on the quality of the water used to prepare the electrolyte solutions. For the highest purity solutions, the rate constants approach those measured on platinum. The linear scan voltammetrlc peak potential for ascorbic acid shifts 390 mV when electrodes are activated. 

Such reduction In overpotentlal Is the largest observed for a bare glassy carbon electrode. The presence of surface qulnones may be Indicative of activation but does not appear to mediate the heterogeneous electron transfer. XFS results support the presence of qulnones as a minor constituent on the surface. 

The purpose of this paper Is 1) to describe the electrochemistry of ferrl-/ferro-cyanlde and the oxidation of ascorbic at an activated glassy carbon electrode which Is prepared by polishing the surface with alumina and followed only by thorough sonlcatlon 2) to describe experimental criteria used to bench-mark the presence of an activated electrode surface and 3) to present a preliminary description of the mechanism of the activation. The latter results from a synergistic Interpretation of the chemical, electrochemical and surface spectroscopic probes of the activated surface. Although the porous layer may be Important, Its role will be considered elsewhere. 

Figure 1. The redox behavior of I,4-dlhydrobenzene at a deactivated versus various activated glassy carbon electrodes.

Figure 2. Cyclic voltammograms of ferrl-/ ferro-cyanlde couple at an activated glassy carbon electrode at scan rates of a) 20, b) 50, and c) 100 mV s . See text for details.

Figure 3. Cyclic voltammograms of ascorbic acid at a freshly polished, active (a) and a deactivated (b) glassy carbon electrode surface. See text for details.

Another electro-oxidation example catalyzed by bimetallic nanoparticles was reported by D Souza and Sam-path [206]. They prepared Pd-core/Pt-shell bimetallic nanoparticles in a single step in the form of sols, gels, and monoliths, using organically modified silicates, and demonstrated electrocatalysis of ascorbic acid oxidation. Steady-state response of Pd/Pt bimetallic nanoparticles-modified glassy-carbon electrode for ascorbic acid oxidation was rather fast, of the order of a few tens of seconds, and the linearity was observed between the electric current and the concentration of ascorbic acid. 

The pentapeptides, met- and leu-enkephalin, have been detected in rat striatum tissue by LCEC at a glassy carbon electrode These peptides can be detected directly... 

Christensen PA, Hamnett A, Weeks S A. 1988. In-situ FTIR study of adsorption and oxidation of methanol on platinum and platinized glassy carbon electrodes in sulphuric acid solution. J Electroanal Chem 250 127-142. 

Cherstiouk OV, Simonov PA, Zaikovskii VI, Savinova ER. 2003b. CO monolayer oxidation at Pt nanoparticles supported on glassy carbon electrodes. J Electroanal Chem 554 241-251. 

AlexeyevaN, Laaksonen T. 2006. Oxygen reduction on gold nanoparticle/multi-walled carbon nanotubes modified glassy carbon electrodes in acid solution. Electrochem Commun 8 1475-1480. 

El-Deab MS, Okajima T, Ohsaka T. 2003. Electrochemical reduction of oxygen on gold nano-particle-electrodeposited glassy carbon electrodes. J Electrochem Soc 150 A851-A857. 

Figure 17.12 Direct electrocatal3ftic oxidation of D-fnictose at a glassy carbon electrode painted with a paste of Ketjen black particles modified with D-fructose dehydrogenase from a Gluconobacter species. The enzyme incorporates an additional heme center allowing direct electron transfer from the electrode to the flavin active site. Cyclic voltammograms were recorded at a scan rate of 20 mV s and at 25 + 2 °C and pH 5.0. Reproduced by permission of the PCCP Owner Societies, from Kamitaka et al., 2007.

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