Reactivity theory of transition-metal surfaces: A brønsted-evans- polanyi linear activation energy-free-energy analysis

A study was conducted to demonstrate the application of the Brønsted-Evans-Polanyi (BEP) relationship in the analysis of surface elementary reaction steps. The BEP equation directly related the change in activation energy of the reaction, δE_act to the corresponding change of the reaction energy, δE_r for different surfaces through a constant factor α. The activation energy was deduced from the reaction energy, which was a thermodynamic parameter. An analytic derivation of the BEP equation was presented using a Marcus-type analysis to provide a conceptual frame for the discussion. The physical chemistry of the surface reaction was viewed as a potential-energy curve crossing problem. It was found that surface electronic factors required a modification of this simple potential-energy crossing model.