Peroxidase-like catalytic properties of Fe3O4 nanoparficles （NPs） with three different sizes, synthesized by chemical coprecipitation and sol-gel methods, were investigated by UV-vis spectrum analysis. By comparing Fe3O4 NPs with average diameters of 11, 20, and 150 nm, we found that the catalytic activity increases with the reduced nanoparticle size. The electrochemical method to characterize the catalytic activity of Fe3O4 NPs using the response currents of the reaction product and substrate was also developed.
We herein report a one-step, wet-chemical approach to synthesizing gold nanoplates in large quantities via the AuCl4^- thermal reduction process by aniline, without introducing additional capping agent or surfactant. It is found that the reduction kinetics of AuCl4^- is greatly altered by varying the initial molar ratio of aniline to AuCl4^-. Moreover, further investigation reveals that the insitu formed polyaniline could serve effectively as a capping agent to preferably adsorb the { 1 1 1 } facets of gold crystals during a slow reduction process, directing the formation of gold nanoplates.
