Quantitative Studies of the Coverage Effects on Microkinetic Simulations for NO Oxidation on Pt(111)

To advance a reliable microkinetic modeling approach using density functional theory (DFT) energies is of great importance to bridging between experimental results and theoretical calculations, and the current major issue is the coverage effect. In this work, a full microkinetic modeling for NO oxidation using DFT energetics is developed. We show that the calculated turnover frequency (TOF) (0.22 s–1) agrees with the experimental one (∼0.2 s–1) very well, if the coverage effects are properly incorporated. It is found that to include the interactions of adsorbates, namely, (i) O and O, NO and NO (self-interaction), and (ii) O and NO (cross-interaction), is important to obtain accurate kinetic results. Equally important, the interactions between the adsorbates and the transition states of O–O bond breaking and O–NO coupling are also crucial for achieving precise kinetics. We demonstrate that a two-line model can be used to describe accurately both the self and cross adsorbate–adsorbate interactions as well as the coverage effects on the transition states of O2 dissociation and O–NO coupling. The various approximations including Brønsted–Evans–Polanyi (BEP) relations are carefully examined, and the errors involved are quantified. Moreover, a one-line model is tested, which is a simplified approach but gives rise to a good agreement with experimental results.