Quantifying and Managing the Structural Lifetimes of Nanocrystalline Model Catalysts in CO

Abstract Dynamic restructuring of metal nanocrystals (MNCs) in reactive gas atmospheres challenges the static paradigm of shape-controlled model catalysis. Quantifying their structural lifetimes under operating conditions is essential, yet predicting atomistic kinetics over macroscopic time scales remains a fundamental challenge. Here, we transform unpredictable structural lifetimes into a manageable variable using an improved environmental kinetic Monte Carlo (iEKMC) method. It overcomes traditional time scale limits and predicts Pt NC reshaping kinetics across macroscopic time domains under CO atmospheres. By resolving the combined effects of initial morphology, particle size, and temperature, we establish a quantitative framework that determines the reshaping time of MNCs under reaction conditions, showing consistency with benchmarking experiments. We demonstrate that selected combinations of particle size and reaction conditions can effectively mitigate restructuring, preserving predesigned MNC morphologies over day-scale observation windows. This work evaluates and manages operando shape stability in a predictive strategy, restoring the core validity of shape-controlled model catalysis.