Low–Energy Metastable Ensemble–Involving Ostwald Ripening of Au Nanoclusters on Anatase TiO2(101) under Oxidizing Conditions

Abstract Supported Au nanoclusters are highly effective catalysts but are susceptible to deactivation via sintering. While Ostwald ripening (OR) is a primary sintering mechanism, its atomic-scale pathways on the anatase TiO2 surface remain poorly understood. Using neural network potential, we investigate the OR process of Au nanoclusters supported on TiO2(101) under oxidizing conditions, identifying Au and AuO as the primary mobile species. A systematic monomer detachment mapping (MDMAP) workflow is developed to efficiently sample the detachment landscape. Subsequent kinetic analysis reveals that low-energy metastable ensembles (LEMEs) serve as essential kinetic intermediates. By evaluating clusters with varying sizes and oxygen coverages, we identify interfacial oxygen as the key regulator of OR kinetics, where moderate oxidation promotes OR through charge stabilization and low Au–Au coordination, while excessive oxidation inhibits monomer detachment. This study provides a comprehensive atomistic perspective on Au nanocluster evolution, offering key insights into the rational design of stable supported catalysts.