Titanate anodes

D.S. Ginley, M.A. Butler, Photoelectrolysis of water using iron titanate anodes. J. Appl. Phys. 

Lin J-Y, Hsu C-C, Ho H-P et al (2013) Sol-gel synthesis of aluminum doped lithium titanate anode material for lithium ion batteries. Electrochim Acta 87 126-132... 

Zhu W, Yang M, Yang X, Xu X, Xie J, Li Z (2014) Supercritical continuous hydrothennal synthesis of lithium titanate anode materials for lithium-ion batteries. US Patent 20140105811 Al. Accessed 17 Apr 2014... 

TYZOR TPT and the tetraethyl titanate, TYZOR ET [3087-36-3], have also been prepared by direct electrochemical synthesis. The reaction involves anode dissolution of titanium in the presence of the appropriate alcohol and a conductive admixture (3). 

Vashook V, Muller R, Zosel J, Ahlbom K, Ullmann H, and Guth U. Catalytic and electrical properties of SOFC anode material based on lanthan-chromite-titanate. Mat.-wiss. U. Werkstofftech. 2002 33 335-338. 

Figure 10-26 is an energy diagram for the photoelectrol3dic decomposition of water in a cell consisting of a metallic cathode and an n-type anode of strontium titanate, of which the band gap is 3.2 eV and the flat band potential at pH 0 is Vnhe ... 

Fig. 10-26. Energy diagram for a cell of photoelectrolytic decomposition of water consisting of a platinum cathode and an n-type semiconductor anode of strontium titanate of which the Fermi level at the flat band potential is higher than the Fermi level of hydrogen redox reaction (snao > epM+zHj) ) he = electron energy level referred to the normal hydrogen electrode ri = anodic overvoltage (positive) of hole transfer across an n-type anode interface t = cathodic overvoltage (negative) of electron transfer across a metallic cathode interface.

Finally, NMR has also be used to study other spinels materials that do not contain manganese. For example, the intercalation/deintercalation of lithium titanate spinels such as Li4/3+Ji5/304 and Lii.i-Tii.904+a have been investigated. These materials may be used as anode materials in combination with cathodes operating at 4 V (vs Li) to produce cells with potentials of ca. 2.5 V. These materials are either diamagnetic or metallic, and unlike the mangan-ates, only very small differences in shifts are seen for Li in the different sites of the spinel structure. Nonetheless, these shift differences are enough to allow the concentrations of the different sites to be quantified and monitored following insertion of Li or as a function sample preparation method. ... 

These observations are consistent with an indirect mechanism of oxygen evolution, involving the photogeneration and the subsequent photo-oxidation of the surface peroxo-titanates. Apparently, the photo-oxidation of the peroxo species constitutes the slow step of the overall reaction and proceeds at a significant rate only in the presence of an anodic... 

As the Tis-0 radical is, at the same time, the precursor to the long-lived peroxo-titanate species (cf. reactions (24) and (27)), reaction (46) accounts also for the photoluminescence at 840 nm observed by Nakato et al. for the Ti02 electrode irradiated with near-UV light and subjected to moderate anodic bias. 

It is, of course, tempting to draw a parallel between the photo-oxidation of water at titanium dioxide and the well-known irreversibility of O2 generation at the anodes with metallic conductivity. There are, however, some indications that the pathway involving surface-bonded peroxo-titanate intermediates is not the only possible one. Recent experiments, performed with beryllium-doped Ti02 photoanodes, have shown no evidence for the formation of any perceptible amount of the peroxo spedes l This coincided with a substantial cathodic shift of the onset potential and a strong increase of the anodic photocurrent for these electrodes , suggesting a different mechanism of oxygen evolution. 

Mavroides J. G., Kafalos J. A. and Kolesar D. F. (1976), Photoelectrolysis of water in cells with strontium titanate(lV) anodes , App/. Phys. Lett. 28, 241-243. 

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