Carbon electrocatalytic activity

Isse, A.A., Gottardello, S., Maccato, C. and Gennaro A. (2006b) Silver nanoparticles deposited on glassy carbon. Electrocatalytic activity for reduction of benzyl chloride. Electrochem. Commun. 8, 1707-1712. 

In acid electrolytes, carbon is a poor electrocatalyst for oxygen evolution at potentials where carbon corrosion occurs. However, in alkaline electrolytes carbon is sufficiently electrocatalytically active for oxygen evolution to occur simultaneously with carbon corrosion at potentials corresponding to charge conditions for a bifunctional air electrode in metal/air batteries. In this situation, oxygen evolution is the dominant anodic reaction, thus complicating the measurement of carbon corrosion. Ross and co-workers [30] developed experimental techniques to overcome this difficulty. Their results with acetylene black in 30 wt% KOH showed that substantial amounts of CO in addition to C02 (carbonate species) and 02, are... 

Carbon shows reasonable electrocatalytic activity for oxygen reduction in alkaline electrolytes, but it is a relatively poor oxygen electrocatalyst in acid electrolytes. A detailed discussion on the mechanism of... 

Yang H, Vogel W, Lamy C, Alonso-Vante N. 2004. Structure and electrocatalytic activity of carbon-supported Pt-Ni alloy nanoparticles toward the oxygen reduction reaction. J Phys ChemB 108 11024-11034. 

Gavrilov AN, Savinova ER, Simonov PA, Zaikovskii VI, Cherepanova SV, Tsirlina GA, Parmon VN. 2007. On the influence of the metal loading on the stmcture of carbon-sup-ported PtRu catalysts and their electrocatalytic activities in CO and methanol electrooxidation. Phys Chem Chem Phys 40 5476-5489. 

Battery applications Titanium containing y-Mn02 (TM) hollow spheres synthesis and catalytic activities in Li-air batteries [123] Orthorhombic LiMn02 nanorods for lithium ion battery application [124] Electrochemical characterization of MnOOH-carbon nanocomposite cathodes for metal—air batteries [125] Electrocatalytic activity of nanosized manganite [126]... 

A new approach to improve the performance of solar devices using natural pigments is to employ carbon nanotube (CNT)-based counter-electrodes. As previously reported, the excited dye transfers an electron to Ti02 and so it acquires a positive charge. Then, the cationic molecule subtracts an electron from the counterelectrode which is transported by the electrolyte. This reaction is usually catalyzed by means of conductive and electrocatalytically active species for triiodide reduction of carbon coatings. CNTs have a high superficial area, which represents a very... 

Modified electrodes containing cyclam derivatives have been prepared. The approach utilizing cyclam incorporated in Nafion film on a carbon electrode shows that the catalytic efficiency of the system is much lower than observed when the catalyst is adsorbed on the mercury. With electrodes prepared following the Langmuir Blodgett technique, only the electrode materials that allow the orientation of the monolayer so that the tail points to the substrate were found to be electrocatalytically active.165... 

It was established that carbons grafted with pyrolyzed Co(III)-Me complexes increase its electrocatalytic activity, and the temperature of pyrolysis is very important. This can be seen from the plots in Figure 3. The maximum catalytic effect is achieved for the samples annealed near 600°C, decreasing at higher temperatures and almost vanishing at 800°C (Figure 4). 

M. Zhang, Y. Yan, K. Gong, L. Mao, Z. Guo, and Y. Chen, Electrostatic layer-by-layer assembled carbon canotube multilayer film and its electrocatalytic activity for 02 reduction. Langmuir 20, 8781-8785 (2004). 

G.C. Zhao, Z.Z. Yin, L. Zhang, and X.W. Wei, Direct electrochemistry of cytochrome c on a multi-walled carbon nanotube modified electrode and its electrocatalytic activity for the reduction of H2O2. Electrochem. Commun. 7, 256-260 (2005). 

A. Salimi, A. Noorbakhsh, and M. Ghadermarz, Direct electrochemistry and electrocatalytic activity of catalase incorporated onto multiwall carbon nanotubes-modified glassy carbon electrode. Anal. Biochem. 344,16-24 (2005). 

The electrocatalytic activity of composite carbon-supported materials based on heterocyclic polymers and nickel (Pani-C-Ni, Ppy-C-Ni, P3MT-C-Ni) was also studied... 

In Chapter 2, the electrochemical oxidation of carbon monoxide, which is considered as the key intermediate for methanol oxidation, is investigated using electrochemical and spectroscopic methods for polycrystalline and single crystal platiniim electrodes. In Chapter 3, the electrochemical oxidation of methanol on the same electrodes was treated. In Chapter 4, electrocatalytic activities of platinum modified by adding secondary elements will be disciissed. 

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... 

Generally, carbon materials show a low electrocatalytic activity. But often it is very dependent on the history of the electrode, for example, due to removing of a surface coverage or due to roughening of the surface. Thus it may be difficult to get reproducible results, and frequently a long time of changing conditions after start of the electrolysis is observed. 

A polypyrrole film electrochemically deposited on gold electrodes from an MeCN-liCl04/Co(OAc)2 solution shows electrocatalytic activity in dioxygen reduction [404]. The catalytic electroreduction of dithio dipropionic acid (PSSP) with the water-soluhle cohalt(II I)tetrakis(4-trimethyl-ammonium phenyl) porphyrin (CoTMAP) has heen studied. The Co catalyst adsorbed on the glassy carbon electrode plays a major role in the electroreductive cleavage of the S—S bond [405]. 

Anfolini et al. [161] also compared SAB and Vulcan XC-72 as possible candidates in MPLs, but in this case they used carbon cloth DLs with two MPLs. From their results, it was concluded that the Vulcan XC-72 gave slightly higher electrocatalytic activity for fhe ORR. On the other hand, MPLs near the FF that used SAB had better performance. Thus, it was suggested that for improved fuel cell performance af high pressures (around 3 atm), the ideal cathode MPL compositions would use the Vulcan XC-72 in the MPL next to the CL and SAB in the MPL next to the flow fields. 

The evolving structural characteristics of CLs are particularly important for further analysis of transport of protons, electrons, reactant molecules (O2), and water as well as for the distribution of electrocatalytic activity at Pt-water interfaces. In principle, the mesoscale simulations allow relating these properties to the choices of solvent, ionomer, carbon particles (sizes and wettability), catalyst loading, and hydration level. Explicit experimental data with which these results could be compared are still lacking. Versatile experimental techniques have to be employed to study particle-particle interactions, structural characteristics of phases and interfaces, and phase correlations of carbon, ionomer, and water in pores. 

To summarize, one can say that the electrochemical performance of CNT electrodes is correlated to the DOS of the CNT electrode with energies close to the redox formal potential of the solution species. The electron transfer and adsorption reactivity of CNT electrodes is remarkably dependent on the density of edge sites/defects that are the more reactive sites for that process, increasing considerably the electron-transfer rate. Additionally, surface oxygen functionalities can exert a big influence on the electrode kinetics. However, not all redox systems respond in the same way to the surface characteristics or can have electrocatalytical activity. This is very dependent on their own redox mechanism. Moreover, the high surface area and the nanometer size are the key factors in the electrochemical performance of the carbon nanotubes. 

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