Mixed Metal-oxide Semiconductors

Semiconductor Loading (metal Rate of gas evolution (umol/li) Ref 

Tabic 6.S Effect of co-catalyst loaded NaTaOi photocatalysts on water splitting [112], 

KsMsSisOis (M =Ta and Nb) [119] possesses a unique pillared structure, in which three comer sharing MOe chains are bridged by ditetrahedral SisOy units. No photocatalytic activity for water splitting was observed from KsNbsSisOis, 4.1 eV bandgap, with or without cocatalyst addition. The M-O-M bond angles in 

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In this chapter, we first discuss mixed metal oxide semiconductors used in both fields. We then discuss photoelectrochemical properties of BiV04 semiconductors. Finally, we discuss our high-throughput screening system for mixed metal oxide semiconductors. 

Mixed Metal Oxide Semiconductors Used for Photoelectrodes and Photocatalysts... 

Hannay, N. Semiconductors, Eeinhold Publishing Co., Inc., New York (1959). Ward, R. Structure and Properties of Mixed Metal Oxides, in Cotton s Progress in Inorganic Chemistry, Vol. I, 465-536, Interscience Publishers, New York (1959). 

A superconductor is a material which conducts electricity without resistance and the exclusion of the interior magnetic field (Meissner effect) below a certain critical temperature Tc- Superconductivity occurs in a wide variety of materials, including elements, various metallic alloys and some heavily-doped semiconductors. Mixed metal oxides belong to the class of high-temperature superconductors (Tq > 30 K). 

Cobalt(Il) dicobalt(Ill) tetroxide [1308-06-17, Co O, is a black cubic crystalline material containing about 72% cobalt. It is prepared by oxidation of cobalt metal at temperatures below 900°C or by pyrolysis in air of cobalt salts, usually the nitrate or chloride. The mixed valence oxide is insoluble in water and organic solvents and only partially soluble in mineral acids. Complete solubiUty can be effected by dissolution in acids under reducing conditions. It is used in enamels, semiconductors, and grinding wheels. Both oxides adsorb molecular oxygen at room temperatures. 

Some insulating oxides become semiconducting by doping. This can be achieved either by inserting certain heteroatoms into the crystal lattice of the oxide, or more simply by its partial sub-stoichiometric reduction or oxidation, accompanied with a corresponding removal or addition of some oxygen anions from/into the crystal lattice. (Many metal oxides are, naturally, produced in these mixed-valence forms by common preparative techniques.) For instance, an oxide with partly reduced metal cations behaves as a n-doped semiconductor a typical example is Ti02. 

The above mechanistic aspect of electron transport in electroactive polymer films has been an active and chemically rich research topic (13-18) in polymer coated electrodes. We have called (19) the process "redox conduction", since it is a non-ohmic form of electrical conductivity that is intrinsically different from that in metals or semiconductors. Some of the special characteristics of redox conductivity are non-linear current-voltage relations and a narrow band of conductivity centered around electrode potentials that yield the necessary mixture of oxidized and reduced states of the redox sites in the polymer (mixed valent form). Electron hopping in redox conductivity is obviously also peculiar to polymers whose sites comprise spatially localized electronic states. 

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