Issue 45, 2015

Co-titration of AgNO3 and HAuCl4: a new route to the synthesis of Ag@Ag–Au core–frame nanocubes with enhanced plasmonic and catalytic properties

Abstract

We report a new strategy for the synthesis of Ag@Ag–Au core–frame nanocubes by co-titrating AgNO3 and HAuCl4 concomitantly into an aqueous suspension of Ag nanocubes in the presence of ascorbic acid (AA) and poly(vinyl pyrrolidone) at room temperature. When the molar ratio of AgNO3 to HAuCl4 was larger than three, we discovered that the added Ag+ ions could effectively push the galvanic replacement reaction between Ag nanocubes and HAuCl4 backward and thus inhibit it, making it possible to achieve the co-reduction of the two precursors by AA without involving any galvanic replacement. By increasing the volumes of the two co-titrated precursors, we validated that the added AgNO3 and HAuCl4 were completely reduced to Ag and Au atoms, respectively, followed by their co-deposition onto the edges, corners, and then side faces of the Ag nanocubes in a fashion similar to seeded growth. As a result, the co-titration process offers an exquisite control over the relative amounts of Ag and Au atoms being deposited by simply varying the feeding ratio between the two precursors. We also demonstrated that the Ag@Ag–Au core–frame nanocubes exhibited unique plasmonic properties. Upon etching of the Ag templates from the core–frame nanocubes by an oxidant, we obtained Ag–Au nanoframes that could serve as an active catalyst for the reduction of 4-nitrophenol by NaBH4.

Graphical abstract: Co-titration of AgNO3 and HAuCl4: a new route to the synthesis of Ag@Ag–Au core–frame nanocubes with enhanced plasmonic and catalytic properties

Supplementary files

Article information

Article type
Paper
Submitted
19 sept. 2015
Accepted
26 oct. 2015
First published
27 oct. 2015

J. Mater. Chem. C, 2015,3, 11833-11841

Co-titration of AgNO3 and HAuCl4: a new route to the synthesis of Ag@Ag–Au core–frame nanocubes with enhanced plasmonic and catalytic properties

X. Sun and D. Qin, J. Mater. Chem. C, 2015, 3, 11833 DOI: 10.1039/C5TC03002A

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