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AgCu bimetallic materials have attracted significant interest as catalysts for selective oxidation reactions. Near‐surface alloys of Ag on Cu have been shown to activate O2 efficiently at exposed reverse‐segregated isolated Cu atoms within the surface Ag layers. This study focuses on the synthesis of nanoparticle analogs of these alloys and measurement of their performance for ethylene and propylene epoxidation. Supported Cu/SiO2 catalysts were prepared by strong electrostatic adsorption and partial galvanic replacement of Cu atoms with Ag cations in aqueous media, which led to bimetallic nanoparticles of 3–10 nm average size and 0.25–1.6 Ag:Cu atomic ratios. Galvanic exchange stoichiometry, elemental maps and UV–vis spectroscopy reveal coexistence of Ag and Cu in the nanoparticles. Diffuse reflectance infrared spectra of bound CO indicate the formation of nanoparticles with a Cu core and Ag shell when catalysts with high Ag:Cu ratios are reduced to metallic form. The bimetallic catalysts show improvement over monometallic Ag and Cu and their physical mixtures, exhibiting higher rates, higher initial selectivity than Ag, and resistance to secondary reactions that decrease the selectivity of Cu catalysts at higher alkene conversion. These results demonstrate a simple synthesis method of more selective bimetallic AgCu nanoparticles with core‐shell like structures, which may be of use in a variety of selective oxidation reactions.
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Synthesis of Composition-Tunable Ag-Cu Bimetallic Nanoparticles Through Plasma-Driven Solution Electrolysis
Bimetallic nanomaterials have shown great potential across various fields of application. However, the synthesis of many bimetallic particles can be challenging due to the immiscibility of their constituent metals. In this study, we present a synthetic strategy to produce compositionally tunable silver–copper (Ag-Cu) bimetallic nanoparticles using plasma-driven liquid surface chemistry. By using a low-pressure nonthermal radiofrequency (RF) plasma that interacts with an Ag-Cu precursor solution at varying electrode distances, we identified that the reduction of Ag and Cu salts is governed by two “orthogonal” parameters. The reduction of Cu2+ is primarily influenced by plasma electrons, whereas UV photons play a key role in the reduction of Ag+. Consequently, by adjusting the electrode distance and the precursor ratios in the plasma–liquid system, we could control the composition of Ag-Cu bimetallic nanoparticles over a wide range.
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- Award ID(s):
- 2011401
- PAR ID:
- 10590037
- Publisher / Repository:
- Nanomaterials
- Date Published:
- Journal Name:
- Nanomaterials
- Volume:
- 14
- Issue:
- 21
- ISSN:
- 2079-4991
- Page Range / eLocation ID:
- 1758
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript
- Journal Article:
- https://doi.org/10.3390/nano14211758
