Oxygen terminator

Fig. 26. STM images of the oxygen pre-covered platinum(l 1 1) surface during reaction with hydrogen. Images were recorded at a temperature of T = 111 K with a time interval of 625 K. The white ring in the upper right corner is associated with a reaction front of OH intermediates from the autocatalytic reaction. The outside is characterized by an oxygen-terminated surface, whereas water molecules from the reaction are identified inside the ring. Adapted with permission from Reference (757).

The nature of the bonding of oxo groups to molybdenum has been discussed in several reviews.80 92 93 There are three components to molybdenum-oxygen terminal bonds (Mo—Ot), comprising a o interaction along the bond axis (z axis) and two mutually perpendicular n components, each formed by the overlap of an oxgyen p orbital (px or py) with the appropriate molybdenum d orbital (dxz or dyz). Normally, each component is considered to... 

Reproducible electrochemical analysis of phenolic compounds by high-pressure liquid chromatography with oxygen-terminated diamond sensor... 

ELECTROCHEMICAL PROPERTIES OF OXYGEN-TERMINATED DIAMOND ELECTRODES... 

Diamond surfaces after anodic oxidation treatment involve oxygen-containing surface functional groups. The electron-transfer kinetics for ions and polar molecules are expected to be quite different. Fe(CN)l /4 was highly sensitive to the surface termination of diamond. For an anionic reactant, there was an inhibition of the electron transfer for the oxygen-terminated diamond electrodes compared with the hydrogen-terminated diamond electrodes, and there was also an acceleration of the electron transfer for oxygen-terminated diamond for some cationic reactants such as Ru(NH3) +/3+ and Fe2+/3+. These results can be explained by electrostatic effects, which interact between the ionic... 

Fig. 1.3. Two views of the crystal structure of zinc oxide (ZnO). Left Perspective view perpendicular to the c-axis. The upper side is the zinc terminated (0001) plane, the bottom, plane is oxygen terminated (0001). Right View along the c-axis on the zinc terminated (0001) plane...

The wurtzite lattice of ZnO and its low-index surfaces are shown in Fig. 4.5. The basic low index surface terminations are (0001), (0001), (1010), and (1120). The (0001) and (0001) represent the zinc and oxygen-terminated surfaces of the polar 0001 direction, which corresponds to the 111 direction of the cubic zincblende lattice. In contrast to the polar (100) and (100) surfaces of the zincblende lattice, the surfaces with threefold symmetry (111)... 

The work functions and ionization potentials of sputter-deposited ZnO and ZnO Al films are shown in Fig. 4.13. The different Fermi level positions of ZnO and ZnO Al for deposition at room temperature in pure Ar are also observed in the work function. The undoped films prepared under these conditions have a work function of 4.1eV, while the Al-doped films show values of 3.2eV. The difference is almost of the same magnitude as for the Fermi level position and, therefore, explained by the different doping level. Also the ionization potentials are almost the same under these preparation conditions. The work function of the undoped material is close to the value reported by Moormann et al. for the vacuum-cleaved Zn-terminated (0001) surface [20], The same authors report a work function of 4.95 eV for the oxygen terminated ZnO(OOOl) surface, which is in good agreement with the values obtained for films deposited with >5% oxygen in the sputter gas. Since the Fermi level position of the undoped ZnO films does not depend on the oxygen content in the sputter gas (Fig. 4.12), the different work functions correspond to different ionization potentials. 

Fig. 8.14. SEM micrographs of etched ZnO single crystals. The crystals were etched either in hydrochloric acid (top) or in sodium hydroxide solution (bottom). The graph shows the zinc terminated (001) (left) and the oxygen terminated (001) (right) surface after the respective etching step. The angles 7 spanned by the two opposite edges and <5 between the (101) faces of the etch crater are about 130° and 123°, respectively...

In the cited work (Ivandini et al. 2006), the authors outlined that the oxygen-terminated BDD performed worst than the hydrogen-terminated one because the carboxyl functional groups of the oxalic acid molecule may be repulsed by the negative O-terminated electrode surface. 

Class II, in which a more limited cooperative effect is obtained by means of finite chains with the acetal oxygens terminating the chains. In three of the seven reducing sugars in this class, the finite chain originates with the anomeric hydroxyl... 

CoO (111) (rocksalt) (lxl) Oxygen termination with fee stacking, top layer contraction of 17% to 1.06 A from bulk 1.27 A. LEED/9/... 

Sinee the Cope elimination reaetion of amine oxides proeeeds with intramoleeular proton abstraction by the A -oxide group aeeording to Eq. (5-122), it is not surprising that with dimethyl sulfoxide as solvent the reaetion oeeurs at room temperature [328, 331]. Pro tie solvents require temperatures of 120 to 150 °C beeause hydrogen bonding of the oxygen terminal makes the reaetion more diffieult. 

The polyhedral (MO ) building blocks of virtually all polyoxoanions are linked in such a way as to result in each polyhedron having either one or two (mutually cis) unshared vertices. The metal atoms are displaced from the centers of their coordination polyhedra toward these unshared vertices. These displacements correspond to the formation of short metal oxygen terminal bonds resulting from oxygen Pjt donation into the metal s vacant d-orbitals. Such terminal oxygens, which are very weakly basic, form part of the external surfaces of the polyoxoanions and effectively prevent fruther polymerization. Very rarely (about three examples... 

---