Stochastic Control: Transition from Differentiated to Undifferentiated Kinetic Growth in Ag Nanoprisms

Abstract

A seeded process based on the staged addition of sodium borohydride and hydroquinone (HQ) to silver nitrate was used to form aqueous nanocolloids consisting of tabular triangular structures. The unique selectivity of HQ as a reducing agent was used to look at the factors that affect the formation of these triangular nanoprisms, including pH, choice of stabilizer, and addition point for the stabilizer. A critical factor in the formation of these systems was the stabilizer, with sodium citrate being more effective than either poly(vinyl pyrrolidone) or poly(vinyl alcohol) at forming large nanoprisms, and with large differences seen if the stabilizer is added before or after the seed particle was formed. The results are explained used a stochastic model for crystal growth, with a transition from slow, differentiated kinetic growth based on edge-defect termination to rapid, undifferentiated kinetic growth based on 2-dimensional nucleation.