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Orthogonal Deposition of Au on Different Facets of Ag Cuboctahedra for the Fabrication of Nanoboxes with Complementary Surfaces

Abstract

We report the fabrication of Ag-Au cuboctahedral nanoboxes enclosed by {100} and {111} facets, respectively, through the orthogonal deposition of Au on two different facets of Ag cuboctahedra. Specifically, we titrate aqueous HAuCl4 into an aqueous mixture containing Ag cuboctahedra, ascorbic acid, and NaOH (under a basic condition), in the presence of poly(vinylpyrrolidone) (PVP) and cetyltrimethylammonium chloride (CTAC), respectively. In the case of PVP, the oxidation of Ag was initiated from the {111} facets of the cuboctahedra through the galvanic replacement reaction between Au(III) and Ag, accompanied by the deposition of Au onto the {100} facets. Because the dissolved Ag(I) ions could react with NaOH to form Ag2O on the {111} facets and thus terminate the galvanic reaction, the Au(III) ions would be further reduced by ascorbate monoanion (HAsc−) to generate Au atoms for their continuing deposition on the {100} facets, converting Ag cuboctahedra to Ag@Au{100} cuboctahedra. Upon the etching of Ag from the core, we obtained Ag-Au cuboctahedral nanoboxes enclosed by {100} facets. In contrast, when CTAC was present, the oxidation of Ag through galvanic reaction could continuously proceed on {100} facets as the dissolved Ag(I) ions would react with the excessive amount of Cl− ions derived from CTAC to produce soluble AgCl2− ions rather than insoluable Ag2O. As a result, the dissolved Ag(I) ions and the Au(III) would be co-reduced by HAsc− for the generation of Ag and Au atoms, followed by their co-deposition onto {111} facets for the generation of Ag@Au{111} concave cuboctahedra. After the removal of Ag from the core by etching, we obtained Ag-Au{111} cuboctahedral nanoboxes enclosed by {111} facets. Both samples of cuboctahedral nanoboxes exhibited strong optical absorption in the infrared region. Interestingly, the cuboctahedral nanoboxes enclosed by {111} facets embraced significantly enhanced catalytic activity toward the reduction of 4-nitrophenol by NaBH4 relative to their counterparts encased by {100} facets.

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Publication details

The article was received on 30 Sep 2019, accepted on 21 Nov 2019 and first published on 22 Nov 2019


Article type: Paper
DOI: 10.1039/C9NR08420G
Nanoscale, 2019, Accepted Manuscript

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    Orthogonal Deposition of Au on Different Facets of Ag Cuboctahedra for the Fabrication of Nanoboxes with Complementary Surfaces

    J. Ahn, J. Kim and D. Qin, Nanoscale, 2019, Accepted Manuscript , DOI: 10.1039/C9NR08420G

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