Surfaces metal oxide

Chemisoq)tion bonding to metal and metal oxide surfaces has been treated extensively by quantum-mechanical methods. Somoijai and Bent [153] give a general discussion of the surface chemical bond, and some specific theoretical treatments are found in Refs. 154-157 see also a review by Hoffman [158]. One approach uses the variation method (see physical chemistry textbooks) ... 

Goodman D W 1996 Chemical and spectroscopic studies of metal oxide surfaces J. Vac. Sc/. Technol. A 14 1526... 

Once a metal surface has been conditioned by one of the above methods, a coupling agent composed of a bifimctional acid—methacrylate similar to a dentin adhesive is appHed. This coupling material is usually suppHed as a solvent solution that is painted over the conditioned metal surface. The acidic functional group of the coupling molecule interacts with the metal oxide surface while the methacrylate functional group of the molecule copolymerizes with the resin cement or restorative material placed over it (266,267). 

Volume 45 Transition Metal Oxides. Surface Chemistry and Catalysis by H.H. Kung... 

Polymeric surfaces are fundamentally different from metal oxide surfaces, and consequently the technical challenges to obtaining strong and durable adhesive... 

Priming to improve adhesion Table 7 Surface energies of polymeric and metal oxide surfaces 459... 

A thin film (typically 50-200 nm) is grown from solution to serve as a hybrid inorganic/organic gradient between the metal (oxide) surface and the organic primer or adhesive. XPS indicates that the surface is silane-rich and the... 

Clifford, P. K. Mechanisms of Gas Detection by Metal Oxide Surfaces. Ph.D. Dissenatiori, Car-[legie-Melion University, (July 1981). 

With the objective of producing model systems to mimic the metal oxide surfaces of catalysts, a great deal of effort has been devoted to the preparation of large polymetallate structures. 

The concentration dependence of CO oxidation over Pt at (02) (CO) l differs from the concentration dependence of CO oxidation over copper chromite at (02)°-2(C0). This can be explained by the fact that after the departure of a C02 molecule, the reoxidation of platinum surfaces is slow but the reoxidation of base metal oxide surfaces is fast. On the other hand,... 

All boiler system waterside surfaces need the protection given by the smooth, hard, tenaciously adherent magnetite layer. The magnetite film sometimes may sparkle because of the precipitation of fine magnetite crystals onto the metal-oxide surface. Magnetite film formation is best achieved under stable, low-oxygen content operating conditions at a pH level of 10.5 to 11.5 (possibly up to 12.0). 

Davies, S. and Morgan, J. J. (1989). Manganese (II) oxidation kinetics on metal oxide surfaces, /. Colloid... 

It is unlikely in real tribological events that adsorbed mono-layers work solely to provide lubrication. Instead, adsorption and chemical reactions may occur simultaneously in most cases of boundary lubrication. For example, fatty acid is usually regarded as a friction modiher due to good adsorp-tivity, meanwhile its molecules can react with metal or a metal oxide surface to form metallic soap which provides protection to the surface at the temperature that is higher than its own melting point. 

The coprecipitation (CP) method was the first method that was found to be effective in depositing nanosized gold particles on base metal oxide surfaces [1, 16]. In this method, an aqueous solution of HAuCLj and the nitrate of a base metal is poured, under vigorous stirring, into an aqueous solution of Na2C03 at 70°C in a short period (within 3 min). The adequate concentration of both the solutions is 0.1-0.4M. The pH of the mixed solution can be maintained at about 9 by using... 

Figure 9.17. Mars-Van Krevelen mechanism for the oxidation of CO on a metal oxide surface. A characteristic feature is that lattice oxygen is used to oxidize the CO, leaving a defect that is replenished in a separate step by oxygen from the gas phase.

A highly detailed picture of a reaction mechanism evolves in-situ studies. It is now known that the adsorption of molecules from the gas phase can seriously influence the reactivity of adsorbed species at oxide surfaces[24]. In-situ observation of adsorbed molecules on metal-oxide surfaces is a crucial issue in molecular-scale understanding of catalysis. The transport of adsorbed species often controls the rate of surface reactions. In practice the inherent compositional and structural inhomogeneity of oxide surfaces makes the problem of identifying the essential issues for their catalytic performance extremely difficult. In order to reduce the level of complexity, a common approach is to study model catalysts such as single crystal oxide surfaces and epitaxial oxide flat surfaces. 

H.H.Kung, Transition Metal Oxides Surface Chemistry and Catalysis,Stud.Surf.Sci. Catal., bl.45, Elsevier, Amsterdam, 1990. 

Onishi, H., Yamaguchi, Y, Fukui, K. and Iwasawa, Y. (1996) Temperature-jump STM observation of reaction intermediate on metal-oxide surface./. Phys. Chem., 100, 9582-9584. 

Evaporation of superstechiometric atoms of metals from metal oxide surfaces... 

It was shown in a number of works [29] that impurity conductivity of thin zinc oxide films are extremely sensitive to adsorption of atoms of various metals (see Chapters 2 and 3). Using this feature of oxide films, we first employed the sensor method to study evaporation of superstechiometric atoms of metals from metal oxide surfaces, zinc oxide in particular [30]. 

Streitz FH, Mintmire JW (1994) Electrostatic potentials for metal-oxide surfaces and interfaces. Phys Rev B 50(16) 11996-12003... 

In the past few years, a large number of experimental and theoretical studies have focused on metal oxide surfaces with the aim of gaining insight into their catalytic, photocatalytic, and gas-sensing activity [68]. Owing to its thermodynamic stability and relatively easy preparation, the rutile Ti02(l 10) surface has evolved into one of the key models for metal oxide surfaces. For example, it has been extensively used in the research of biocompatible materials, gas sensors, and photocatalysts [69]. 

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