Team With a Midas Touch: Silver Nanoparticles Turned to Gold and Vice Versa by IIT Team

A group of researchers from the esteemed Indian Institute of Technology (IIT) in Chennai, India has surprisingly transformed silver nanoparticles into gold and vice versa by simply replacing their atoms one at a time, according to a recent study published in the journal, Nature Communications. The arrangement and shape of these materials remained identical before and after the change; however, they differed in their chemical composition.

T. Pradeep, a professor from the Department of Chemistry at IIT Madras, said that the technique is similar to changing a silver Natrajan statue on a table to its gold version. He added that such a feat is now possible purely at the nanoscale because of the limited systems available, but there are chances of taking it to the macroscopic level in the near future.

When silver and golden nanoparticles are mixed in a solution kept at room temperature, there is a replacement of atom by atom. Both these materials have the same atomic arrangements but vary in their masses. Once mixed in the solution, a silver nanoparticle changes to a golden nanoparticle and vice versa. If it's possible to change materials simply by replacing atoms one at a time, it's also possible to create novel alloys with unique and unknown properties, according to Professor Pradeep. It's important to note that silver does not get transformed into gold. The only thing that happens is that one structure of silver changes into another similar structure of gold and the other way round. In the end, the number of atoms of both the materials is the same.

When a silver nanoparticle made up of 25 atoms comes in touch with a gold nanoparticle of 25 atoms in the solution, a single atom of gold particle is replaced by a silver nanoparticle, which leads to the formation of the alloy AuAg24. The removed silver atom from the silver nanoparticle takes up the place of the gold atom and forms an AgAu24 alloy. With the progress of the reaction, the number of atoms in one particular alloy increases steadily while it decreases in the other metal. In simpler terms, the alloy containing high quantities of gold gets denser in silver gradually, and by single changes in the atom, it transforms into a 100 percent silver nanoparticle.