Transport limitations and bistability for in situ CO oxidation at RuO₂(110): First-principles based multiscale modeling

We present a first-principles based multiscale modeling approach to heterogeneous catalysis that integrates first-principles kinetic Monte Carlo simulations of the surface reaction chemistry into a fluid dynamical treatment of the macroscale flow structures in the reactor. The approach is applied to a stagnation flow field in front of a single-crystal model catalyst using the CO oxidation at RuO2(110) as representative example. Our simulations show how heat and mass transfer effects can readily mask the intrinsic reactivity at gas-phase conditions typical for modern in situ experiments. For a range of gas-phase conditions we furthermore obtain multiple steady states that arise solely from the coupling of gas-phase transport and surface kinetics. This additional complexity needs to be accounted for when aiming to use dedicated in situ experiments to establish an atomic-scale understanding of the function of heterogeneous catalysts at technologically relevant gas-phase conditions