Carbon electrochemical activity

FIGURE 2-13 STM image of an electrochemically activated glassy-carbon surface. (Reproduced with permission from reference 46.)... 

Tian ZQ, Ren B, Mao BW. 1997. Extending surface Raman spectroscopy to transition metal surfaces for practical applications. 1. Vibrational properties of thiocyanate and carbon monoxide adsorbed on electrochemically activated platinum surfaces. J Phys Chem B 101 1338-1346. 

Said subjects are being analyzed in this work. Also, the authors have attempted to show that in order to be suitable for lithium-ion applications, a carbon-based active material has to meet a complex number of physicochemical and electrochemical characteristics. A simple check of galvanostatic behavior, which is often used today to conclude about carbon s suitability for lithium-ion battery technology, is rarely enough for making an accurate assessment. 

Composite electrodes made of two carbon components were evaluated experimentally as anodes for Li-ion batteries. The electrochemical activity of these electrodes in the reaction of reversible lithium intercalation ffom/to a solution of LiPF6 in ethyl carbonate and diethyl carbonate was studied. Compositions of the electrode material promising for the usage in Li-ion batteries were found. 

The source carbon materials show a significant electrochemical activity for lithium intercalation though the reversible capacity is relatively low and tends to reduce with cycling. For the thermally expanded graphite... 

The main idea of the model is that in order for the electrically conductive additive to effectively fulfill its functions, it must form a closed cluster (skeleton of the interconnected carbon particles, which is the conducting pass in electrode matrix). Once the sufficient conductive network was formed, further considerable increase of additive content is not needed, as it leads to decrease in the percentage of the electrochemically active constituent in the electrode. 

ELECTROCHEMICAL ACTIVITY OF CARBONS MODIFIED BY d-METAL COMPLEXES WITH ETHANOLAMINES... 

With regard to biosensor applications, a wide variety of electrochemically active species (ferrocene, ruthenium complexes, or carbon and metal (Pt, Pd, Au...) [185,186] were also introduced into the sol-gel matrices or adsorbed to improve the electron transfer from the biomolecules to the conductive support [187,188]. For instance, glucose oxidase has been trapped in organically modified sol-gel chitosan composite with adsorbed ferrocene to construct a low-cost biosensor exhibiting high sensitivity and good stability [189]. 

M. Musameh, N.S. Lawrence, and J. Wang, Electrochemical activation of carbon nanotubes. Electrochem. Commun. 7,14-18 (2005). 

E. Horozova, N. Dimcheva, and Z. Jordanova, Adsorption, catalytic and electrochemical activity of catalase immobilized on carbon materials. Z Naturforsch. 52, 639-644 (1997). 

The stability during potential cycling and ORR activity of Pt (20 wt°/o) supported on MWCNTs and carbon black was also investigated [136]. Two different potential cycling conditions were used, namely lifetime (0.5 to 1.0 V vs. RHE) and start-up (0.5 to 1.5 V vs. RHE). Pt supported on MWCNTs catalyst exhibited a significantly lower drop in normalized electrochemically active surface area (ECA) values compared to Pt supported on Vulcan (Fig. 14.10), showing that MWCNTs possess superior stability to commercial carbon black under normal and severe potential cycling conditions [137]. 

The electrocatalytic activity of the nanostructured Au and AuPt catalysts for MOR reaction is also investigated. The CV curve of Au/C catalysts for methanol oxidation (0.5 M) in alkaline electrolyte (0.5 M KOH) showed an increase in the anodic current at 0.30 V which indicating the oxidation of methanol by the Au catalyst. In terms of peak potentials, the catalytic activity is comparable with those observed for Au nanoparticles directly assembled on GC electrode after electrochemical activation.We note however that measurement of the carbon-supported gold nanoparticle catalyst did not reveal any significant electrocatalytic activity for MOR in acidic electrolyte. The... 

In this chapter, two carbon-supported PtSn catalysts with core-shell nanostructure were designed and prepared to explore the effect of the nanostructure of PtSn nanoparticles on the performance of ethanol electro-oxidation. The physical (XRD, TEM, EDX, XPS) characterization was carried out to clarify the microstructure, the composition, and the chemical environment of nanoparticles. The electrochemical characterization, including cyclic voltammetry, chronoamperometry, of the two PtSn/C catalysts was conducted to characterize the electrochemical activities to ethanol oxidation. Finally, the performances of DEFCs with PtSn/C anode catalysts were tested. The microstmc-ture and composition of PtSn catalysts were correlated with their performance for ethanol electrooxidation. 

Because the reaction in a CL requires three-phase boundaries (or interfaces) among Nafion (for proton transfer), platinum (for catalysis), and carbon (for electron transfer), as well as reacfanf, an optimized CL structure should balance electrochemical activity, gas transport capability, and effective wafer management. These goals are achieved through modeling simulations and experimental investigations, as well as the interplay between modeling and experimental validation. 

As noted above, the lithium ions flow through the electrolyte whereas the electrons generated from the reaction, Li = Li+ + e, go through the external circuit to do work. Thus, the electrode system must allow for the flow of both lithium ions and electrons. That is, it must be both a good ionic conductor and an electronic conductor. As discussed below, many electrochemically active materials are not good electronic conductors, so it is necessary to add an electronically conductive material such as carbon... 

Sensing of chlorine is possible with a phthalocyanine-based optode that is elec-trochemically reset [101]. Also a direct electrochemical Clark-type sensor employing carbon electrodes has been investigated [102]. For this type of sensor, the various types of carbon gave different responses and the edge-plane sites of graphitic electrodes were identified as electrochemically active. Both chlorine reduction and chlorine evolution were studied and the effects of the trichloride anion, Ch", were highlighted. 

The anode layer of polymer electrolyte membrane fuel cells typically includes a catalyst and a binder, often a dispersion of poly(tetraflu-oroethylene) or other hydrophobic polymers, and may also include a filler, e.g., acetylene black carbon. Anode layers may also contain a mixture of a catalyst, ionomer and binder. The presence of a ionomer in the catalyst layer effectively increases the electrochemically active surface area of the catalyst, which requires a ionically conductive pathway to the cathode catalyst to generate electric current (16). 

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