Surface area controlled differential catalytic activities of one-dimensional chain-like arrays of gold nanoparticles

We report on the formation of linear assemblies of citrate-stabilized spherical gold nanoparticles (GNPs) in the presence of acetanlide in aqueous medium. The length of the assembly was dependent on the concentration of acetanilide. At higher concentrations branching of the assembly occurred instead of an increase in the length of the assembly. Interestingly, the catalytic properties of the assemblies were dependent on the concentration of the acetanilide. This means the effective surface areas of the metal nanoparticles in the assembly were much dependent on the length of the assembly, which could be controlled by the concentration of acetanilide. The results indicate a linear dependence of the effective surface area on the concentration of acetanilide. Also, the observations suggest that the presence of NaBH4 in the reaction medium led to the fusion of GNPs into fibrous form thus reducing the effective surface area for catalysis.