Question

1. You will be given a solution of silver nitrate from which to synthesize silver nanoprisms. The silver in the nanoprisms is Ag0. What do you need to do to the silver to get it into that form? Which would you use to do that: KBr, H2O2, NaBH4, sodium citrate? Why?

Answer 1

NaBH₄

In first small spherical silver nanoparticles were prepared by the rapid reduction of the precursor with NaBH4 at ice-bath temperature. After being heated to 70 °C, further reduction of the precursor contributed to the formation of additional small spherical silver nanoparticles attributed to the catalysis effect of the silver particles formed at the low temperature. The residual precursor after the formation of the small spherical silver nanoparticles is necessary to promote the dissolution of the small nanoparticles and their transformation into the triangular nanoprisms. a stepwise reduction method was developed for the preparation of triangular silver nanoprisms in the absence of surfactant or special capping-agent. In this approach, first a part of the precursor, silver nitrate, was reduced rapidly by NaBH4 to produce small spherical silver nanoparticles at icebath temperature. The remaining precursor was further reduced by citrate under elevated temperature to result in the formation of additional small spherical nanoparticles and induce the transformation of the spherical nanoparticles into the triangular nanoprisms. It is shown that the formation of the triangular nanoprisms is dependent on the molar ratios of NaBH₄ and trisodium citrate used in the reactions. A balance between the precursor contributed to the formation of the small spherical particles and that to the transformation of the spherical nanoparticles is critical for the synthesis of the triangular nanoprisms.