BEP Relation of Metal Oxides with Different Crystal Structures
摘要
This work explored the Br∅nsted-Evans-Polanyi (BEP) relations for the dissociation reaction of small molecules such as CO, O<sub>2</sub>, NO and N<sub>2</sub> on two metal oxides with different crystal structures, i.e. the rutile- and NaCl-typed ones, aiming to shed light on the differences on the BEP relation between the metal oxides and transition metal, as well as between the metal oxides with different crystal types. Firstly, they basically possessed the same slope of the BEP relation with that on the transition metal surface, but give a large difference for the intercept term; The intercept of the BEP relation on metal oxides was shown much smaller than that on the flat metals and even smaller than that on the stepped metals. The reason for reduction of the intercept of the BEP relations was mainly ascribed to the relative weak binding ability of metal oxides; The dissociation configuration at TS is more FS-like, and the energy barrier of reverse synthesis reaction is much lower. Secondly, the similar BEP relations were presented on the rutile-typed oxide (110) and NaCl oxide (100) surface, because of their similar local structure characteristics, implying the dependence of surface structure on the intercept of BEP relations, and an extended study on the metal carbide and nitrides confirmed this point. Furthermore, the BEP relation on metal oxides could be further divided into two groups based on the transition state (TS) configuration type, and the BEP relation with late typed TS exhibited a larger slope (close to 1) and a smaller intercept in comparison with that of early typed TS.