Density Functional Studies of the Adsorption and Dissociation of CO₂Molecule on Fe(111) Surface

Abstract

Spin-polarized density functional theory calculation was carried out to characterize the adsorption and dissociation of CO(2) molecule on the Fe(111) surface. It was shown that the barriers for the stepwise CO(2) dissociation reaction, CO(2(g)) --> C(a) + 2O(a), are 21.73 kcal/mol (for OC-O bond activation) and 23.87 kcal/mol (for C-O bond activation), and the entire process is 35.73 kcal/mol exothermic. The rate constants for the dissociative adsorption of CO(2) have been predicted with variational RRKM theory, and the predicted rate constants, k(CO(2)) (in units of cm(3) molecule(-1) s(-1)), can be represented by the equations 2.12 x 10(-8)T(-0.842) exp(-0.258 kcal mol(-1)/RT) at T = 100-1000 K. To gain insights into high catalytic activity of the Fe(111) surface, the interaction nature between adsorbate and substrate is also analyzed by the detailed electronic analysis.