First-Principles Analysis of Structure Sensitivity in NO Oxidation on Pt

Abstract

The kinetics of Pt-catalyzed NO oxidation on both Pt(111) and Pt(321) are quantified from first-principles using a coverage-aware “reaction site” kinetic model. Density functional theory (DFT)-parametrized cluster expansions are used to predict oxygen coverages and availability of O2 dissociation sites as a function of reaction conditions. DFT calculations are used to parametrize a Bronsted–Evans–Polanyi relationship for O2 dissociation on Pt(321). Ensemble averaging over available sites and their corresponding rates yields total reaction rates. Predicted apparent activation energies and rate orders are consistent with the experimental observations on single crystal catalysts and are most strongly determined by the coverage dependence of O adsorption rather than the statistical availability of O2 dissociation sites. Rates and rate derivatives are similar on the two surfaces over the range of experimental observation and are predicted to differ more significantly outside this range.