A Good Prediction of the Overall Reaction Rate May Not Mean a Correct Description of the Reaction Kinetics: A Case Study for CO Oxidation on RuO2(110) Surfaces

Kinetic models based on density functional theory (DFT) calculations have been widely utilized in heterogeneous catalysis to predict catalytic performance and to understand detailed reaction mechanisms. It is well known that the intrinsic errors associated with an approximate DFT functional can significantly influence the theoretical predictions; therefore, the choice of a working functional is crucial. In the present study of the CO oxidation reaction on the RuO2(110) surface, we have investigated the performances of 13 popular DFT functionals via the extended phenomenological kinetic (XPK) simulations, while RPBE has been identified as the most reliable functional for this catalytic system. We found that, although some functionals could yield a similar maximum overall reaction rate under certain CO partial pressure, they might support distinctly different reaction mechanisms. Hence, even though the overall reaction rate is a key property in the reaction kinetics, which is also the most popular metric for choosing the DFT functional and assessing the modeling, we emphasized that a good prediction of the overall reaction rate under certain reaction conditions does not guarantee a correct description of the reaction kinetics. We found that, rather than a single overall reaction rate, the kinetic trends (e.g., the pressure dependence of the reaction rate, also known as the reaction order) are more robust metrics in comparison with the experimental data.

Automated summary

Kinetic models based on DFT calculations are widely used in heterogeneous catalysis, where the choice of a suitable functional is crucial for accurate predictions. In the study of CO oxidation, RPBE was identified as the most reliable functional for the catalytic system, emphasizing the importance of kinetic trends over overall reaction rates in assessing reaction kinetics.