Catalytic selectivity effect surface reconstruction

In selective oxidations, the presence or absence of spillover oxygen has an effect on the facetting and reconstruction of MoC crystallites, as demonstrated using SEM and AFM. These results highlight the necessity to keep the surface smicture in an optimal configuration during the whole catalytic cycle. A modified Mars-van Krevelen model can account better than previous ones for the reduction-oxidation cycle and the change in number of the active sites as a function of the reaction conditions. 

Chemical reconstruction of alloy and/or bimetallic surfaces will be more complex, and it is obvious that the catalysis of alloy and/or bimetallic surface can not be explained by the traditional idea of ligand effect and ensemble effect for the sites. That is, chemical reconstruction of alloy surface will occur by selective segregation or selective reaction of metal atoms. As a result, a new surface will be prepared sometimes, which is responsible to the prominent catalytic activity and/or selectivity of alloy and/or bimetallic surfaces. If this is the case, the catalysis of alloy surface is entirely different form the idiomatic idea of ligand effect" and " ensemble effect". 

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