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'Defective' Graphene Could Filter Water, Improve Fuel Cells

To say graphene is a material with a lot of promise might be the understatement of the decade. The atom-thin sheet of carbon is stronger than steel, more conductive than copper, and has several other fantastic qualities — but many of them require perfect, unbroken sheets of the stuff, which scientists still struggle to create reliably. But even "defective" graphene can excel in certain situations, researchers have discovered.

Tiny imperfections in the graphene sheet may reduce its strength, but if they're the right size, they also act as pores through which particles can pass — particles as small as protons or as large as salts and water pollutants. The researchers examined various defect sizes and the mechanism behind how each transmitted particles.

Computer model of a proton-compatible gap. The colors represent different kinds of atoms: grey, carbon; red, oxygen; white, hydrogen. University of Minnesota

With smaller perforations, the graphene sheet causes protons to be shuttled from one side to the other without permitting through any of the molecules they come from. This could open the way for fuel cells that siphon power from hydrogen orders of magnitude faster than anything we have today. Larger holes could be made to allow water molecules to pass but not larger salts or contaminants — like toxins, bacteria and viruses.

There is still the problem of manufacturing enough graphene to meet demand, but it seems that every form of the material, from perfect sheets to scraps to fine powders, will become essential in some way or another.

The study, conceived by Northwestern University's Franz Geiger but carried out by a number of researchers across the country, appeared Tuesday in Nature Communications.

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