Size-controlled synthesis of nanoparticles. 1. "Silver-only" aqueous suspensions via hydrogen reduction

A method for size-controlled synthesis of chemically clean silver nanoparticles is proposed and described. The synthesis is based on the reduction of silver(I) oxide by hydrogen gas in water and offers the advantages of being easily scalable and able to produce essentially naked particles still exhibiting long-term stability with the metal surface readily accessible to various chemical modifications. The method allows synthesis of particles of any diameter between 15 and 200 nm simply by varying the reaction time. The addition of filtration and centrifugation techniques produces suspensions of narrow size distribution and relatively high, 10(12)-10(14) particles/mL, concentration. The addition of various complexating agents potentially allows control of nanoparticle shape. The nanoparticles were characterized by UV-vis spectroscopy, electron microscopy, and electron and X-ray diffraction techniques.