Growth and stabilization of silver nanoplates in aqueous solvent monitored through UV-Vis spectra

Sliver nanoplates were prepared through a visible light induced reduction process by a reaction between sodium citrate and silver nitrate in an aqueous solvent at room temperature. UV-Vis spectra were employed to monitor the growth of the silver nanoplates. The resulting spectra indicated that, at an early stage, the products were spherical particles with planar nanoparticles appearing and growing subsequently. In the last stages of the process, some spherical particles were consumed by the growth of the nanoparticles, through an Ostwald ripening mechanism. Furthermore, it was found that the addition of either Poly(Vinyl Pyrrolidone) (PVP) or excessive citrate could stabilize the colloidal system effectively, and that rigorous stirring was necessary for the anticipant products. Introduction of a large quantities of sodium hydroxide can dramatically accelerate the reactive rate of the photoreduction process.