Main Properties of Bimetallic Systems

The term bimetallic was introduced by Sinfelt to account for the fact that a catalyst may contain a muldtude of phases containing the acdve metallic components. Of these many phases, a characteristic is the binary alloy. The term alloy can describe a broad range of situations from well-defined phases or solid solutions to surface alloys in cases where bulk alloys are not thermodynamically favoured but a clearly defined surface local arrangement is obtained. Note that the novel core-shell bimetallic structures are included in this catchall term. An historical overview of the properties of alloys in connection with catalysis has been published by Ponec. At present, a broadly agreed view accepts that alloy components can be chemically recognised and, therefore, supports a somewhat localised interpretation of the alloy nature and properties. Obviously, a delocalised view loses most of its meaning in the case of clusters due to its finite dimensions. 

E [ure 4.2 FTIR spectra of the carbonyl region for a PdovsCuo.js nanostructured alloy after CO adsorption at room temperature (dashed line) and at 573 K (solid line) P 

The use of bimetallic catalysts is a direct consequence of the improved catalytic performance with respect to monometallic systems.1 The localised view mentioned above crystallises in a theory which supports such improved performance in the so-called geometric or ensemble, 

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