Investigating Molecular Adsorption on Graphene-Supported\nPlatinum Subnanoclusters: Insights from DFT + D3 Calculations

Platinum (Pt) subnanoclusters\nhave become pivotal in nanocatalysis,\nyet their molecular adsorption mechanisms, particularly on supported\nversus unsupported systems, remain poorly understood. Our study employs\ndetailed density functional theory (DFT) calculations with D3 corrections\nto investigate molecular adsorption on Pt subnanoclusters, focusing\non CO, NO, N<sub>2</sub>, and O<sub>2</sub> species. Gas-phase and\ngraphene-supported scenarios are systematically characterized to elucidate\nadsorption mechanisms and catalytic potential. Gas-phase Pt<sub><i>n</i></sub> clusters are first analyzed to identify stable configurations\nand assess size-dependent reactivity. Transitioning to graphene-supported\nPt<sub><i>n</i></sub> clusters, both periodic and nonperiodic\nmodels are employed to study interactions with graphene substrates.\nStrong adsorbate interactions predominantly occur at single top sites,\nrevealing distinct adsorption geometries and stabilization effects\nfor specific molecules on Pt<sub>6</sub> clusters. Energy decomposition\nanalysis highlights the paramount role of graphene substrates in enhancing\nstability and modulating cluster-adsorbate interactions. The interaction\nenergy emerges as a critical criterion within the Sabatier principle,\ncrucial for distinguishing between physisorption and chemisorption.\nHybridization indices and charge density flow tendencies establish\ndirect relationships with stabilization processes, underscoring graphene’s\ninfluence in stabilizing highly reactive subnanoclusters. This comprehensive\ninvestigation provides critical insights into molecular adsorption\nmechanisms and the catalytic potential of graphene-supported Pt nanoclusters.\nOur findings contribute to a deeper understanding of nanocatalysis,\nemphasizing the essential role of substrates in optimizing catalytic\nperformance for industrial applications.