One Pot and Room Temperature Photochemical Synthesis of Seed-Mediated Water Soluble Concentric Ag Nanoplates Without H2O2 and NaBH4 Injection

Abstract

In this article, we report a novel, simple, one pot, and scalable method for the synthesis of Ag nanoplates with various shapes of triangles, prisms, and disks with controllable size and few nanometer thickness. We combined the salt reduction method and seed-mediated photochemical approach to harvest silver nanoplates. In this approach, NaBH4 and H2O2 were omitted from the procedure completely. UV-Vis spectroscopy revealed that the in-plane plasmon resonance can be tuned from visible up to near-infrared region. Transmission electron microscopy picturized the thin nanotriangle and nanoplate formation. Using FTIR spectroscopy and systematic synthesis of samples with and without insertion of sodium citrate and PVP, we concluded that Na3CA is a “magic” agent playing etchant and reducing roles at the same time and it is not surprisingly a “surfactant” in this work. It was comprehensively studied that in contrary to the published reports based on salt reduction, injection of H2O2 after the microwave activation of Na3CA in the growth solution cannot etch the silver particles and does not result in the formation of nanoplates. This report opens a new insight into the role of low concentration Na3CA in the preparation of silver nanoplates at high concentrations of silver ions using only seed particles as a bright example of Ostwald ripening at nanoscale. We also invented a dynamic method by means of direct injection of silver ion solution during photochemical reaction to tune the in-plane plasmon resonance of nanoplates.