Hydroquinone (HQ) was used as the principal chemical reducing agent to prepare aqueous silver nanocolloids from silver nitrate. The data demonstrate that HQ is unable to initiate the particle growth process on its own, but is able to sustain particle growth in the presence of pre-existing metallic clusters. This unique selectivity is similar to that seen in photographic systems. Data are presented on two different approaches to initiating the HQ growth process. Very low levels of sodium borohydride can be used to form seed particles. Alternatively, the data show that controlled growth can be initiated by exposing the samples to UV radiation, relying on the photoreactivity of hydroquinone to start the process. These results were used to explore the dynamics of very dilute NaBH4 seed particles. They also were used to create nonspherical disk and triangular-plate morphologies directly from solution, without the need for subsequent reformation or template processing.

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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.