Density Functional Theory Calculations and Analysis of Reaction Pathways for Reduction of Nitric Oxide by Hydrogen on Pt(111)

Reaction pathways are explored for low temperature (e.g., 400 K) reduction of nitric oxide by hydrogen on Pt(111). First-principles electronic structure calculations based on periodic, self-consistent density functional theory (DFT-GGA, PW91) are employed to obtain thermodynamic and kinetic parameters for proposed reaction schemes on Pt(111). The surface of Pt(111) during NO reduction by H-2 at low temperatures is predicted to operate at a high NO coverage, and this environment is explicitly taken into account in the DFT calculations. Maximum rate analyses are performed to assess the most likely reaction mechanisms leading to formation of N2O, the major product observed experimentally at low temperatures. The results of these analyses suggest that the reaction most likely proceeds via the addition of at least two H atoms to adsorbed NO, followed by cleavage of the N-O bond.