Beyond Mean-Field Microkinetics: Toward Accurate and Efficient Theoretical Modeling in Heterogeneous Catalysis

Kinetics as the link between atomic scale properties and macroscopic functionalities is indispensable in describing surface chemical reactions and computation-based rational design of catalysts. Kinetic Monte Carlo (KMC) on the explicit lattice can resolve events taking place on the catalytic surfaces at the atomic level. It can explicitly account for spatial correlations due to lateral interactions among adsorbates, which have been proved to significantly affect the surface chemical reactions. However, the disparity in time scales of various processes (e.g., adsorption/desorption, diffusion, and reaction) usually makes brute force KMC simulations impractical. Here, we propose a method, namely XPK, to extend the phenomenological kinetics (PK) for the accurate and efficient microkinetic modeling of heterogeneous catalysis. XPK is achieved through a hybrid between the diffusion-only KMC on the explicit lattice to evaluate the reaction propensities and later an implicit lattice KMC in the PK form to evolve the coverages and calculate the final rates. XPK is tested against the explicit lattice KMC using model systems and is applied to describe the volcano curve of ammonia decomposition on the close-packed surfaces of transition metals with lateral interactions among adsorbates being introduced. The results demonstrate the accuracy of XPK, show the significant influences of the lateral interactions on both the shape of the volcano curve and the position of the volcano top, and highlight the usefulness of XPK in describing complex catalytic kinetics of practical interest and predictive capability in the computation-based rational design of catalysts.