Reductive dopants

Typical oxidising dopants used include iodine, arsenic pentachloride, iron(III) chloride and NOPF6. A typical reductive dopant is sodium naphthalide. The main criteria is its ability to oxidise or reduce the polymer without lowering its stability or whether or not they are capable of initiating side reactions that inhibit the polymers ability to conduct electricity. An example of the latter is the doping of a conjugated polymer with bromine. Bromine it too powerful an oxidant and adds across the double bonds to form sp3 carbons. The same reaction may occur with NOPF, but at a lower rate. 

Both anatase and mtile are broad band gap semiconductors iu which a fiUed valence band, derived from the O 2p orbitals, is separated from an empty conduction band, derived from the Ti >d orbitals, by a band gap of ca 3 eV. Consequendy the electrical conductivity depends critically on the presence of impurities and defects such as oxygen vacancies (7). For very pure thin films, prepared by vacuum evaporation of titanium metal and then oxidation, conductivities of 10 S/cm have been reported. For both siugle-crystal and ceramic samples, the electrical conductivity depends on both the state of reduction of the and on dopant levels. At 300 K, a maximum conductivity of 1 S/cm has been reported at an oxygen deficiency of... 

For the production of lamp-filament wire, aluminum, potassium, and siHcon dopants are added to the blue oxide. Some dopants are trapped in the tungsten particles upon reduction. Excess dopants are then removed by washing the powder in hydroflouric acid. Eor welding electrodes and some other appHcations, thorium nitrate is added to the blue oxide. After reduction, the thorium is present as a finely dispersed thorium oxide. 

The pros and cons of oxidative dehydrogenation for alkene synthesis using doped cerianites as solid oxygen carriers are studied. The hydrogen oxidation properties of a set of ten doped cerianite catalysts (Ce0.9X0.1Oy, where X = Bi, In, La, Mo, Pb, Sn, V, W, Y, and Zr) are examined under cyclic redox conditions. X-ray diffraction, X-ray photoelectron spectroscopy, adsorption measurements, and temperature programmed reduction are used to try and clarify structure-activity relationships and the different dopant effects. 

---