Matryoshka-caged gold nanorods: Synthesis, plasmonic properties, and catalytic activity

Matryoshka-caged gold nanorods (mCGNRs) were successfully synthesized by alternating between a seed-mediated silver-coating method and galvanic replacement reactions (GRRs). As the number of matryoshka layers of the mCGNRs increased, the plasmon resonance peak broadened and was red-shifted, and the catalytic activity towards the reduction of 4-nitrophenol (4-NTP) increased. When mCGNRs with 6 layers were used as nanocatalysts in the reduction of 4-nitrophenol, the reaction rate coefficient was 5.2- and 3.7-times higher than that of the gold-nanorod- and caged-gold-nanorod-catalyzed reductions of 4-nitrophenol, respectively. In addition, the surface-plasmon-resonance-based absorption of light enhanced the catalytic performance of the mCGNRs. With the support of a polyurethane foam, the mCGNRs synthesized in this study can be applied as recyclable heterogeneous catalysts for the reduction of 4-nitrophenol.