Electrocatalytic Ability

The high electron transfer ability of porous, activated carbon materials can improve their electrochemical performance with respect to that at conventional pyrolitic and glassy carbon electrodes. It should be noted, however, that—as occurring for these latter electrodes—electrode conditioning and electrochemical 

FIGURE 7.17 CVs for a 2.5 mM solution of dopamine in 0.50 M phosphate buffer, pH 7.0, at (a) unmodified glassy carbon electrode, (b) SWNT-modified glassy carbon electrode. Potential scan rate, 50 mV/sec. 

FIGURE 7.18 SEM images of (a) aligned CNTs electrode and (b) thionine-modified aligned CNTs electrode. Insets in (a) and (b) illustrate the corresponding TEM images. (Erom Zhao et al., 2007. Electrochem. Commun. 9, 65-70, with permission.) 

CNTs look like bigger feathers. The TEM image shows that there is much fleecy stuff on the surface of CNTs. 

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This observation must be linked with the beneficial accumulation of electrons in the POM framework. It was checked that NO is also electrocatalytically reduced in the same potential domain. Concerning nitrate, it is worth reminding that a comparative study of several metal ion-substituted heteropolyanions including aj- and 2-P2W17M and 2-P2Wi5Mo2M where Mn", Fe", Co", Ni"Cu", Zn" and =y (where =y indicates the absence of M) most heteropolyanions, except those substituted by Cu or Ni do not show any important electrocatalytic ability toward its reduction [160a]. Specifically,... 

Indeed, other electrocatalytic processes were studied, including the pioneering work on chlorate reduction by the six-electron reduction product of 12-molybdophosphate in water-dioxane solutions [169]. This process, extended to bromate, has become a classical test of the electrocatalytic abilities of several POMs [see Table 13]. 

Content of Sb in the crystals of Sn02. Proper doping of Sb can increase the conductivity and also the electrocatalytic ability of the Sn02 electrodes. Usually the behavior of the electrode do not vary much more when Sb content lies in 3-6%. But higher or smaller doping can decrease the service life of the electrode. 

The XRD patterns of electrodes fabricated at different temperatures (Fig. 14.6) showed that rutile Sn02 was detected at every temperature. Diffraction lines of electrode prepared at 500° C are broadened, indicating the nanosized crystallites in the surface coating of the electrode. When the annealing temperature increases from 500 to 700°C, the intensity of the peaks increases sharply and it means that the crystal of electrode surface grows more integrated. Better electrocatalytic ability can be achieved. 

Although Sn02 electrode possesses better electrocatalytic ability for organic degradation, a most important problem for the Sn02 electrode is its shorter service life... 

Available analysis methods are important for evaluation of the electrocatalytic abilities of electrodes. It is complicated to have a whole estimation system. New evaluation, new technologies, and methods are always needed and also very important for developing new electrode materials. 

Richards G, Swavey S (2009) Electrooxidation of Fe, Co, Ni and Cu metalloporphyrins on edge-plane pyrolytic graphite electrodes and their electrocatalytic ability towards the reduction of molecular oxygen in acidic media. Eur J Inorg Chem 35 5367-5376... 

Novel types of synthesis of modem electrocatalysts revealed that the properties of electrode materials can be affected by the controlled formation of nano-sized, finely dispersed, electrocatalyst particles. In the case of DSA, already the traditional preparation procedure involves the thermal decompositiOTi of the corresponding chlorides after dissolution in an appropriate solvent (usually a solvent of low viscosity, e.g., 2-propanol) [3], Recently, sol-gel synthesis was introduced for DSA preparatirMi, with the main effect being related to the increase in the real surface area of the anode [9,10], The effect is recognized as the geometric factor of increased electrocatalytic ability in addition to an electronic factor related to the chemical structure of electrocatalyst [2,4], which is essential for step (6). The geometric factor is important since the measure for the reaction rate is the current density, i.e., the current per surface area of the electrode available for the reaction. Thus, the reaction rate can be considerably increased by the application of nano-3D electrodes, which are porous systems with an extended real surface area. The polarization curves for the CER on... 

They reported 141) that (1) the complex 15 without any pendent base slowly oxidizes H2 with an overpotential of -0.73 V (using -0.14 V vx. Fc/Fc (ferrocene/ferrocenium) as the thermodynamic potential for H /H2 in CH3CN) (2) introduction of pendent N bases into the backbone of the diphosphine hgands (complex 16) causes a rapid heterolytic addition of H2 to form 17 and (3) the electrocatalytic ability of 16 is improved at low overpotentials (less than 0.08 V and a turnover frequency of H2 oxidation between 0.01 and 0.5 s under 1 atm of H2) presumably through an intermediate such as 18 as predicted by our DFT calculations. 

The anthraquinone moieties on the surface of electrode show excellent electrocatalytic ability towards oxygen. The reaction involves the reduction of anthraquinone to dihydranthraquinone via two electrons and two protons. Afterwards, dihydranthraquinone reacts with oxygen and converts it to hydrogen peroxide while anthraquinone is regenerated. 

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