Preparation And Charaterization Of Hollow Urchin-like Gold Nanopatricles

Nanostructured gold nanoparticles (AuNPs) have revealed great potential applications in manyfields owing to their unique optical and catalytic properties. Among them, urchin-like orbranched gold particles with a rough surface are of great significance. The high surface areaendows them excellent performance in catalysis, surface plasmon resonance, surface-enhancedRaman spectra, electronic devices and biological applications. On the other hand, the hollowmetal nanostructures present many potential applications in catalysts, drug delivery, opticalimaging and nano-reactors.In our work, we used the galvanic replacement reaction between Ag nanoparticles (NPs) andHAuCl4followed by addition of ascorbic acid to generate AuNPs sharing both urchin-like andhollow structures. The AgNPs took as sacrificial templates to guide the hollow structure and theintermediates provided rough surface and active sites for the further deposition of AuNPs, whichoriginated from the reduction of excess HAuCl4by ascorbic acid. These unique structuredAuNPs presented excellent optical properties and great advantages in catalysis applications.Based on the above strategy, we selected AgNO3as additive to guide the formation of hollowunchin-like AuNPs. This greatly facalitates the preparetion process and we considered therelative diffusion rate of the reduced Au (in) and dissolved Ag+(out) controls the finalmorphology of the AuNPs. A long period of incubation time before addition of ascorbic acidmakes a solid urchin-like AuNPs. Similarly to the above system, the catalysis activity of theas-synthesized AuNPs were also measured using the reduction of4-nitrophenol by NaBH4andelectrocatalytic oxidation of glucose as model reactions.Finally, similar structured metal nanoparticles are to be generated and their potentialapplications in different fields, including optics, catalysis and biomedicine are expected.