Apparently copper can be used to scrub pollutants out of the air. Maybe one day a penny can help clean your house.

An easy way to get carbon dioxide out of the atmosphere is to find a chemical that combines easily with it, similar to the way that some metals oxidize. For example, compounds involving copper will usually combine with oxygen in the atmosphere voluntarily without catalysts, covering the surface of the copper material with a green patina, like the Statue of Liberty.

Unlike oxygen, carbon dioxide cannot combine so easily with other materials. It is possible to remove one electron from the molecule to facilitate its integration into other molecules, but that removal requires an electric potential of -1.97 volts, which is unreasonably high for the purpose of processing a single molecule.

One group of scientists found a certain dinuclear copper (I) complex that turns green when exposed to air under a slight electric potential (-0.03 volts). At first, they assumed it was from the exposure to oxygen, but upon closer inspection they learned that this particular form of copper was reacting with carbon dioxide.

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