Encapsulation Dynamics of Platinum Nanoparticles on Titania Supports with Different Oxidation States, Crystal Phases and Facets

Strong metal-support interaction (SMSI) is a key interfacial phenomenon in supported metal catalysis. The Pt/TiO2 system is a classic model for studying the SMSI mechanism. However, a unified quantitative framework for understanding SMSI encapsulation kinetics is still lacking, failing to elucidate how support valence state, crystal phase, crystal facets, and defects synergistically regulate the rate and extent of encapsulation, thus limiting the leap from phenomenological explanation to controllable design. This work addresses these issues by employing neural network potential-driven molecular dynamics simulations to study the dynamic evolution of the Pt/TiO2 interface. By comparing the encapsulation behavior under different Ti oxidation states, oxygen vacancy concentrations, TiO2 crystal phases and facets, the competitive pathways of interfacial evolution from TiOx migration encapsulation and Pt-Ti interdiffusion alloying are revealed. The core innovation of this work lies in the discovery and demonstration that the surface stability of the support (the surface formation energy γf (Ti-O)) is a unified key parameter controlling the encapsulation kinetics: the lower the Ef (the more stable the surface), the weaker the supply of migratable Ti species, and the lower the encapsulation rate and extent; conversely, the encapsulation is more significant. This parameter introduce the structure/defect-dependent kinetic dimension into the quantitative description framework of SMSI. This study establishes a universal picture connecting the support structure, defect state, and interfacial kinetic behavior, providing important theoretical basis and design principles for the controllable regulation of SMSI through rational design of support crystal phase, exposed crystal facets, and defect concentration.