Metal oxide anodes

The oxide coatings are porous and therefore the limitations on operating voltage for platinised titanium anodes apply as well to the oxide-coated titanium electrodes. It has been reported that breakdown of mixed metal oxide anodes may occur at 50-60 V in low-chloride concentration water but at only 10 V in chloride-rich environments . 

Wang Y-Q, Gu B, Xu W-L (2009) Electro-catalytic degradation of phenol on several metal-oxide anodes. J Hazard Mater 162 1159-1164... 

Direct electrooxidation is theoretically possible at low potentials, before oxygen evolution, but the reaction rate usually has low kinetics that depends on the electro-catalytic activity of the anode. High electrochemical rates have been observed using noble metals such as Pt and Pd, and metal-oxide anodes such as iridium dioxide, ruthenium-titanium dioxide, and iridium-titanium dioxide (Foti et al. 1997). 

Johnson et al. (Houk et al. 1998 Johnson et al. 1999) studied the incineration of 4-chlorophenol and benzoquinone using quaternary metal-oxide anodes (Ti, Ru, Sn, and Sb). They demonstrated that this type of electrode is stable and electrochemi-cally active for the oxidation of organic compounds when it is used in the absence of a soluble supporting electrolyte, with a Nation membrane as solid-state electrolyte however, the electrolysis time for complete COD and TOC removal was excessively long and current efficiency was low. 

Figure 16 Schematic representation of the reaction pattern for the oxidation of organic compounds with simultaneous oxygen evolution at metal-oxide anodes reactions (a), (b), (c), d) as in Figure 11 (e) combustion of the organic compound R via electrochemical oxidation mediated by physisorbed hydroxyl radicals (/) selective chemical oxidation of the organic compound at the higher metal oxide surface sites. (From Ref. 15. Copyright 1994, Pergamon Press Ltd. Reprinted with permission.)...

In the electrochemical conversion of hydrocarbons the NEMCA (non-faradaic electrochemical modification of catalytic activity) effect has been reported frequently over metal anodes [13] and rarely over metal oxide anodes [14]. The NEMCA effect is known to promote the rate of oxidation and, to the knowledges of the authors, such enhancement in catalytic activity is generally observed over the metal anodes which have original catalytic activity, e.g. Pt, Pd, Rh and Ag, and is also observed as a non-linear function of the electric current. In the present study, we observed an almost linear increase of activity with increase in the electric current. Lacking a reference electrode, it is beyond the scope of this work to elaborate on the work function of the anode material. However, it is likely that the contribution of the NEMCA effect is neglisible and the electrochemically generated ooxygen species operates in the partial oxidation of alkanes. 

S. Trasatti and G. Lodi, Oxygen and Chlorine Evolution at Conductive Metallic Oxide Anodes, Chapter 10 in ref. 19, Part B. 

Chlorine/Caustic Noble metal oxide anode, brine electrolyte... 

The conducting polymer is roughly 1000 times more conductive than the traditionally used manganese dioxide cathode material and it penetrates more effectively into the porous metal-oxide anode structures, creating more robust capacitor structures. 

FTIR and Raman spectroscopy of nano-SnO anodes at different discharge states in rechargeable lithium batteries have been investigated. The structure and the composition of the SEI layer are characterized with HRTEM and FTIR spectroscopy, respectively. It is found that irreversible reduction of SnO and electrolyte decomposition lead to capacity loss of the metal oxide anodes in the first cycle. Similar to the SEI layer on carbonaceous anode materials, the main components in the SEI layer on discharged nano-SnO electrode include Li COj and ROCOjLi. The reduction of SnO anode is determined to occur above 1.2V and last until rather low voltages. The formation of Li COj dominates the solvent reduction above 0.9V (vs Li/Li ) while the formation of ROCO Li mainly takes place below 0.9V. 

Electrochemical oxidation of organic conqtounds is generally performed using noble metal or metal oxide anodes. In dilute aqueous solutions the primary pathway for oxidation of organic con unds begins with the oxidation of water or OH ions that proceeds according to (5) ... 

Electrode consumption is usually not the critical factor in determining anode life of mixed metal oxide anodes. It is rather the formation of nonconductive oxides between the substrate and the conductive surface film that limits the effective operation of these anodes. Excessive current densities accelerate the buildup of these insulating oxides to unacceptable levels. Mixed-metal oxide anodes have replaced most other types of impressed current anodes in seawater appHcations. 

Cathode materials. Prof. Shi-Gang Sun s group at Xiamen University has developed a strategy of enhancing the rate capability of lithium Mn-rich metal oxide anodes. The lithium Mn-rich metal oxides such as... 

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