In:
ChemNanoMat, Wiley, Vol. 3, No. 4 ( 2017-04), p. 245-251
Abstract:
We report the synthesis of bifunctional Ag@SiO 2 /Au nanoparticles with an “islands in the sea” configuration by titrating HAuCl 4 solution into an aqueous suspension of Ag@SiO 2 core–shell nanocubes in the presence of NaOH, ascorbic acid, and poly(vinyl pyrrolidone) at pH 11.9. The NaOH plays an essential role in generating small pores in the SiO 2 shell in situ , followed by the epitaxial deposition of Au from the Ag surface through the pores, leading to the formation of Au islands (6–12 nm in size) immersed in a SiO 2 sea. By controlling the amount of HAuCl 4 titrated into the reaction system, the Au islands can be made to pass through and protrude from the SiO 2 shell, embracing catalytic activity toward the reduction of 4‐nitrophenol to 4‐aminophenol by NaBH 4 . While the Ag in the core provides a strong surface‐enhanced Raman scattering activity, the SiO 2 sea helps maintain the Au component as compact, isolated, and stabilized islands. The Ag@SiO 2 /Au nanoparticles can serve as a bifunctional probe to monitor the stepwise Au‐catalyzed reduction of 4‐nitrothiophenol to 4‐aminothiophenol by NaBH 4 and Ag‐catalyzed oxidation of 4‐aminothiophenol to trans ‐4,4′‐dimercaptoazobenzene by the O 2 from air in the same reaction system.
Type of Medium:
Online Resource
ISSN:
2199-692X
,
2199-692X
DOI:
10.1002/cnma.201600359
Language:
English
Publisher:
Wiley
Publication Date:
2017
detail.hit.zdb_id:
2827071-X
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