Effect of Support Preparation and Nanoparticle Size on Catalyst-Support Interactions between Pt and Amorphous Silica

摘要

The interaction between catalytic nanopartides (NPs) and their supports, which are often amorphous oxides, has not been well characterized at the atomic level, although it is known that, in some cases, NP support interactions dominate the catalytic activity of the system. Furthermore, there is a lack of understanding of how support preparation affects both the stability of the NP (resistance to sintering) and the catalytic activity. We present first-principles density functional theory (DFT) calculations on amorphous silica supported Pt NPs of various sizes. Our calculations predict that support preparation methods that lead to higher hydroxyl density when NPs are deposited on the support will lead to higher resistance to sintering. We find that the total charge on supported NPs, which can affect catalyst activity, depends linearly on the number of Pt silica bonds formed during NP deposition. The number of bonds between an NP of a known geometry and the silica support with a known hydroxyl density can be estimated from very fast discrete element method simulations, enabling the prediction of both the net charge and the adhesion energy of the particle from a linear fit correlation derived from DFT calculations of a series of differently sized Pt clusters. This work quantifies interactions between Pt NPs and amorphous silica supports and demonstrates a new method for rapid estimation of NP support interactions on amorphous supports.