Technology.am (Apr. 24, 2009) — Michigan University chemists created a zinc-oxide crystal riddled with tiny pores that has the highest surface area of any material in the world.
The one-thirtieth of an ounce of the zinc-oxide crystal has enough surface area to cover an entire football field. This labyrinthine material could eventually store hydrogen for cars or pull carbon dioxide out of the air, said Adam Matzger, the University of Michigan chemist who created the material.”
Each pore is tiny, only a nanometer or two in size, just large enough for two hydrogen atoms, bonded to each other, to slip into a pore and bounce around like a rubber ball. The secret is in the bounce. It’s not instantaneous. Each time a hydrogen molecule hits the wall the hydrogen sticks for a fraction of a second, the product of what’s known as the London dispersion force.
Hydrogen molecules are almost electrically neutral, with two negatively charged electrons flying around two positively charged protons. However, sometimes both electrons end up on the same side of the molecule, giving the first lightest element a slight electrical charge, just enough for the gas to stick to the wall for a slice of a second. Then the electrons zoom away, and the hydrogen molecule bounces away.
Today, hydrogen is stored at very high pressures, very low temperatures, which take very much energy. In fact, it requires much more energy than the hydrogen itself has and that’s why hydrogen-based cars aren’t feasible today.
The new material makes a hydrogen economy more feasible than it was before. Even with the new material, the hydrogen gas has to be stored at about -195 degrees C.
Fortunately, the porous crystals are easy to create. Dumping white zinc salts into an environmentally-friendly solvent and drying the resulting crystals with a vacuum is all to create the pore-filled crystals.