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Mesoscopically Bi-continuous Ag–Au Hybrid Nanosponges with Tunable Plasmon Resonances as Bottom-Up Substrates for Surface-Enhanced Raman Spectroscopy
journal contribution
posted on 2016-10-04, 00:00 authored by Yong Yan, Andreea
Ioana Radu, Wenye Rao, Hongmei Wang, Ge Chen, Karina Weber, Dong Wang, Dana Cialla-May, Jürgen Popp, Peter SchaafAg–Au
hybrid nanosponges (NSs) with controlled porosity and composition
ratio were fabricated through the cyclic electroless deposition of
Ag into the porous Au NSs. In the Ag–Au hybrid NSs, both Au
and Ag components with mesoscaled ligament size are bicontinuously
percolated over the entire structure. The plasmonic properties of
the Ag–Au hybrid NSs differ clearly from those of the Au NSs
and the solid Au–Ag alloy nanoparticles, and two distinct plasmon
peaks were observed which can be attributed to Au and Ag components,
respectively. The plasmonic properties can be well tuned by controlling
the cycles of Ag deposition. Both plasmon peaks attributed to Au and
Ag components blue shift with increasing amount of Ag. The volume
porosity decreases upon increasing amount of deposited Ag. The results
of the theoretical calculations reveal that the deceasing porosity
could play an important role in the blue shift. Moreover, the Ag–Au
hybrid NSs exhibit higher sensitivity in surface-enhanced Raman spectroscopy
(SERS) detection of butter yellow (BY) than the Au NSs due to the
presence of Ag and of the porous structure. Also, the as-prepared
structures present a built-in preference for hydrophobic analytes.