A highly efficient solid-state solar cell (TiO2/dye/CuI) with improved stability was fabricated by controlling the pore filling of the porous dyed TiO2 layer with molten salt capped CuI crystals and improving the TiO2 by necking with ZnO. The molten salt controls the CuI crystal growth and acts as a protective coating for CuI nanocrystals, and necking with the more conductive ZnO improves electrical contact between TiO 2 particles, both contributing to improved cell performance. Cells achieved efficiency as high as 3.8% with improved stability under continuous illumination for about 2 weeks.

An ultrathin overlayer of MgO on TiO2 is shown to drastically improve the stability of solid-state dye-sensitized solar cell using CuI as a hole conductor in addition to solar energy conversion efficiency.

The oxidation of Co͑II͒ at a boron-doped diamond ͑BDD͒ electrode was investigated by use of anodic voltammetry. The results shows that this reaction takes place by a mechanism similar to that of cobalt metal oxidation in alkaline media. The voltammetric curves evidence a strong enhancement of the oxygen evolution current in the presence of Co͑II͒. This behavior is consistent with cobalt oxide formation at the diamond electrode surface. Based upon these results, a simple, straightforward method for the production of high activity films on BDD electrode surfaces is demonstrated. The study of the electrochemical behavior in 1 M NaOH shows that the electrodes thus obtained exhibit promising, stable electrocatalytic performance for oxygen evolution, comparing well with those of thermally deposited cobalt electrodes. The use of BDD as a substrate for the electrocatalytic layers allows the deposition of isolated particles or discontinuous films, thus maximizing the utilization of the catalyst by avoiding the need for thick films.Extensive application of electrolytic processes involving electrocatalysts requires inexpensive, yet highly catalytic materials. Complex metal oxides with spinel structure, in spite of difficulties in achieving high surface area and low resistivity, are very promising as electrocatalysts, because they are active, inexpensive and thermodynamically stable, mainly in alkaline media. 1 Among spinel-type oxides, Co 3 O 4 and other cobalt-based oxides continue to attract considerable interest, mainly due to their outstanding electrocatalytic activity for the evolution and reduction of oxygen ͑see Ref. 2, and references therein͒. These processes are of great importance for various types of electrochemical devices, such as water electrolyzers, fuel cells, secondary metal/air batteries, and metal electrowinning cells.Several methods have been developed for cobalt oxide preparation, such as thermal salt decomposition, 3-7 spray pyrolysis, 8-10 powder immobilization, 11-13 plasma sputtering, 14,15 the sol-gel technique, 16-18 ␥-irradiation, 19 and electrochemical techniques. [20][21][22][23][24][25][26] With the exception of the last two, most of these methods require relatively high temperatures. Low temperature techniques are attractive, because they are convenient, they are compatible with a wide range of substrate materials, and they favor the production of high effective surface areas.Another advantage of the electrodeposition technique is that it allows large-area film formation at room temperature. Furthermore, it was observed that electrochemically generated cobalt oxide films show an unusual variety of redox transitions, suggesting that the film conductivity could be controlled to some extent. 20 However, the number of works that describe the electrodeposition of cobalt oxides on various substrates has been relatively few, although interest appears to be increasing. For example, anodically deposited films were prepared in aqueous solution, either on indium tin oxide ͑ITO͒ glass substrate, 21 or on...

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