Deciphering the fine structure of Pt–Sn sub-nanometer clusters and d-band center tuning mechanism via machine learning
摘要
The targeted modulation of catalytic performance in sub-nanometer Pt–Sn alloy clusters is hampered by the unclear atomic-level structure–property relationship. This knowledge gap stems from their intrinsically diverse and irregular configurations lacking long-range order at sub-nanometer scale. Herien, the machine-learning atomic simulations and DFT calculations were integrated to accurately identify the structural evolution of sub-nanometer Pt–Sn clusters, establishing descriptors of structural and electronic properties across the full compositional range. Global exploration of the potential energy surface establishes a comprehensive structural stability phase diagram for the Pt–Sn system, unveiling a size-dependent “promotion then inhibition” effect on cluster stability and confirming the thermodynamic preference of Pt1Sn1 stoichiometry. Quantitative analysis of cluster structure uncovers a counter-intuitive phenomenon: Sn surface segregation drives the counter-intuitive decrease of surface Pt site density with increasing cluster size. Moreover, when the Pt:Sn ratio reaches 1:2 or lower, surface Pt sites achieve mono-dispersion independently of the overall cluster size. The coordination number of surface Pt is identified as the key quantitative descriptor governing the d-band center, with Pt–Pt bonding playing a significantly stronger role in modulating the d-band center than Pt–Sn interactions. These findings provide a “handbook style” fundamental basis for the rational design of improved sub-nanometer Pt–Sn cluster catalysts.
Graphical abstractThe machine-learning atomic simulations and DFT calculations were integrated to accurately identify the structural evolution of subnanometer Pt-Sn clusters, establishing descriptors of structural and electronic properties across the full compositional range.