Scale-Up of Cluster Beam Deposition to the Gram Scale with the Matrix Assembly Cluster Source for Heterogeneous Catalysis (Catalytic Ozonation of Nitrophenol in Aqueous Solution).

Rongsheng Cai,Francesca Martelli,Chedly Tizaoui,Jerome Vernieres,Stefania Albonetti,Richard E Palmer,Nikolaos Dimitratos

doi:10.1021/acsami.0c05955

Rongsheng Cai, Francesca Martelli + Show 5 more

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https://doi.org/10.1021/acsami.0c05955

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Abstract

The deposition of precisely controlled clusters from the beam onto suitable supports represents a novel method to prepare advanced cluster-based catalysts. In principle, cluster size, composition, and morphology can be tuned or selected prior to deposition. The newly invented matrix assembly cluster source (MACS) offers one solution to the long-standing problem of low cluster deposition rate. Demonstrations of the cluster activities under realistic reaction conditions are now needed. We deposited elemental silver (Ag) and gold (Au) clusters onto gram-scale powders of commercial titanium dioxide (TiO2) to investigate the catalytic oxidation of nitrophenol (a representative pollutant in water) by ozone in aqueous solution, as relevant to the removal of waste drugs from the water supply. A range of techniques, including scanning transmission electron microscopy (STEM), Brunauer-Emmett-Teller (BET) surface area test, and X-ray photoelectron spectroscopy (XPS), were employed to reveal the catalyst size, morphology, surface area, and oxidation state. Both the Ag and Au cluster catalysts proved active for the nitrophenol ozonation. The cluster catalysts showed activities at least comparable to those of catalysts made by traditional chemical methods in the literature, demonstrating the potential applications of the cluster beam deposition method for practical heterogeneous catalysis in solution.

Highlights

Cluster beam deposition (CBD) is a vacuum-based, solventfree method to synthesize metal clusters on surface.[1]
We demonstrate the catalytic activity of Ag and Au clusters physically deposited onto commercial titanium dioxide (TiO2) powders with the matrix assembly cluster source (MACS) in the catalytic ozonation of nitrophenol
The catalytic activities of physically deposited Ag and Au clusters on TiO2 were demonstrated in the oxidation of nitrophenol by ozone in aqueous solution

Summary

Introduction

Cluster beam deposition (CBD) is a vacuum-based, solventfree method to synthesize metal clusters on surface.[1] The clusters produced have no chemical ligands, and contamination levels should be low, so the intrinsic properties of the clusters can be controlled, investigated, and exploited. This may allow the rapid prototyping of novel, cluster-based catalysts for various reactions, since the capacity to vary cluster composition and size compares favorably with the traditional chemical methods. While the first investigations of clusters from the MACS have been reported, heterogeneous catalysis in solution has yet to be demonstrated

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