Ice-formed nanostructures

Researchers at the Environmental Molecular Sciences Laboratory (EMSL) at the US Pacific Northwest National Laboratory have developed an environmentally-friendly way to make nanostructures.

Taking a cue from nature, collaborators from the University of Central Florida, Pacific Northwest National Laboratory and the UK Defence Academy grew cerium oxide nanostructures inside the tiny voids that form in aqueous solutions upon freezing.

By controlling solution freezing rate, nanoparticle concentration and storage temperature, the team’s ice mould method can be used to produce nanostructures with tailored shapes and sizes.

The team’s green chemical method was made possible by two natural phenomena: solute rejection and self-assembly. Upon freezing, aqueous solutions force out, or reject, impurities because they cannot be accommodated in the rigid lattice structure of ice. Depending on the freezing conditions, ice does not form a perfect lattice throughout. Rather, it has tiny pockets and channels. It is into these voids that impurities, in this case cerium oxide nanoparticles, become trapped together and can self-assemble.