Metamorphosis-like photochemical growth route for silver nanoprisms synthesis via the unrevealed key intermediates of nanorods and nanotrapezoids

Photochemical synthesis is a promising strategy for the control of both the size and shape of silver nanoprisms; however, the mechanism of nanoprism formation under irradiation still remains as a mystery. Intermediates, which often contain abundant information about the reaction process, are significant to the understanding of reaction mechanisms. Unfortunately, intermediates are usually hard to be acquired due to the fast reaction rate. Herein, we successfully slow down the conversion rate of the photochemical reactions by enlarging the solution volume and removing morphology-directing agent bis(p-sulfonatophe-nyl) phenylphosphine dihydrate dipotassium. Nanorods and nanotrapezoids were found to be the key intermediates for the photoinduced formation of silver nanoprisms with ~100 nm edge length, especially the nanorods which have never identified as the intermediates for silver nanoprism formation. Characterization methods including time-dependent ultraviolet-visible spectroscopy, high resolution transmission electron microscopy (TEM and HRTEM), and selected area electron diffraction were employed to characterize these intermediates. Based upon the revealed evidences, a plausible metamorphosis-like photochemical growth route for the formation of Ag nanoprisms via the intermediates of nanorods and nanotrapezoid is proposed.