Nanostructured phases oxidation

The synthesis of lithium aluminates for tritium production requires formation of nanostructured phases. These can be made by solid-state reaction, by appropriate mixing of oxide powders [84] or by sol-gel methods [80, 85-87], One technique is the peroxide route where y-Al203 and LiC03 are dissolved in a peroxide (H202) solution. Evaporation of water and calcining the solid residue results in nanophase LiA102. 

N.A.M. Shanid, M.A. Khadar, Evolution of nanostructure, phase transition and band gap tailoring in oxidized Cu thin films. Thin Solid Films 516, 6245-6252 (2008)... 

Many techniques have been used to prepare ZnO-based thin films and nanostructures, such as CVD, electron beam evaporation (EBE), MBE, pulsed laser deposition (PLD), sol-gel, spray pyrolysis, sputtering, and vapor phase growth. To prepare ZnO films or nanostructures, thermal oxidation of Zn and ZnS in air has also been used [124]. However, as for ZnS nanocrystals, wet methods, in this case wet oxidation, are still important techniques for SC processing [112]. 

Electro-catalyst supports play a vital role in ascertaining the performance, durability, and cost of PEMFC and DMFC systems. A myriad of nano-structured materials including carbon nanostructures, metal oxides, conducting polymers, transition metals nitrides and carbides, and many hybrid conjugates, have been exhaustively researched to improve the existing support and also to develop novel PEMFC/DMFC catalyst support. One of the main challenges in the immediate future is to develop new catalyst supports that improve the durability of the catalyst layer and, in a best-case scenario, also impact the electronic properties of the active phase to leapfrog to improve catalyst kinetics. 

The different classes of Ru-based catalysts, including crystalline Chevrel-phase chalcogenides, nanostructured Ru, and Ru-Se clusters, and also Ru-N chelate compounds (RuNj), have been reviewed recently by Lee and Popov [29] in terms of the activity and selectivity toward the four-electron oxygen reduction to water. The conclusion was drawn that selenium is a critical element controlling the catalytic properties of Ru clusters as it directly modifies the electronic structure of the catalytic reaction center and increases the resistance to electrochemical oxidation of interfacial Ru atoms in acidic environments. 

We refrain here from giving an extensive overview of studies on the surface structure of vanadium oxide nanolayers, as this has already been done for up to year 2003 in our recent review [97]. Instead, we would like to focus on prototypical examples, selected from the V-oxide-Rh(l 1 1) phase diagram, which demonstrate the power of STM measurements, when combined with state-of-the-art DFT calculations, to resolve complex oxide nanostructures. Other examples will highlight the usefulness of combining STM and STS data on a local scale, as well as data from STM measurements, and sample area-averaging spectroscopic techniques, such as XPS and NEXAFS, to derive as complete a picture as possible of the investigated system. 

Within the inverse model catalyst approach, the y/7-V309-Rh(l 11) nanostructures have been used to visualize surface processes in the STM with atomic-level precision [104]. The promoting effect of the V-oxide boundary regions on the oxidation of CO on Rh(l 1 1) has been established by STM and XPS by comparing the reaction on two differently prepared y/7-V309-Rh(l 11) inverse catalyst surfaces, which consist of large and small two-dimensional oxide islands and bare Rh areas in between [105]. A reduction of the V-oxide islands at their perimeter by CO has been observed, which has been suggested to be the reason for the promotion of the CO oxidation near the metal-oxide phase boundary. 

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