The tiny nature of nanoparticles results in some useful characteristics, such as an increased surface area to which other materials can bond in ways that make for stronger or more lightweight materials. At the nanoscale, size does matter when it comes to how molecules react to and bond with each other.

A piece of bulk material (for example, a carrot) contains trillions of atoms. Only a small portion of its atoms are on the surface. If you cut a carrot in half, you’ve increased the surface area. If you cut it into slices, you’ve increased it again without increasing the amount of carrot or the number of atoms. However, you have increased the number of atoms exposed on the surface.

Think of nanoparticles as being like shredded carrots: They contain anywhere from a handful of atoms up to a few thousand atoms, and have a larger portion of atoms on the surface.

Increasing the surface area with nanoparticles.
Increasing the surface area with nanoparticles.

With a larger number of atoms on the surface, more atoms are available to interact with the atoms or ions of other substances. For example, molecules in an explosive material and oxygen can interact in what’s called an exothermic reaction, generating heat. When heat is contained, whatever is holding it in bursts, resulting in an explosion.

When the explosive substance is formed of nanoparticles, the increased surface area causes the reaction to occur faster and produces a more powerful explosion because more of the molecules are in contact with oxygen.

This presence of more atoms on the surface of a material can be useful in several applications, including the following:

  • Improving electrodes used in batteries, resulting in increased charging rate and storage capacity of the battery.

  • Improving catalysts to lower the temperature and energy required to run chemical reactions.

  • Improving explosives by increasing the power generated by smaller quantities of materials.