Question

1. The preparation of nanoparticle solutions adds a reducing reagent, sodium borohydride, to an oxidizing agent, hydrogen peroxide. Is it concievable that these two reagents would react with each other?

Answer 1

Most metal nanoparticles are synthesized in a reduction reaction in which dissolved metal ions react with a reducing agent to form elemental metal nanoparticles,

If one does not use a capping reagent or uses a reducing agent that is too strong, a bulk-metal “mirror” or macroscopic metal particles will result. An etching agent is often included to remove more reactive, undesired atoms at the surface of the growing nanoparticle so that the most stable shape is predominant. For metal nanoparticles, a suitable oxidizing agent is often used as an etching agent. The etching agent reoxidizes M0 on less stable surfaces to M+, so that the metal ion can be deposited on more stable particle shapes/sizes.

The oxidation and reduction reactions reach equilibrium and ensure that only the most stable shape and size of nanoparticles survives. Metal complexing agents are added to the reaction to slow the rate of reduction and to stabilize particles of certain shapes and sizes. In this experiment, sodium citrate acts to charge-stabilize the silver nanoprisms; it tunes the reduction rate and stabilizes crystal growth directions.

also NaBH4 is unreactive enough that the reductions can be done in alcohol solution, or even water (as long as they don't take too long); this can be advantageous for polar compounds which can be pretty insoluble in ether. Hydrolysis with acid and water followed by extraction is used to isolate the product (hydrogen gas is produced). hence they do not react.

Hope this helps