A Greenhouse Gas Finds New Purpose

David Ji and his research team have captured atmospheric carbon dioxide — a greenhouse gas — and used it to make an advanced, high-value material for energy-storage devices that power everything from defibrillators to hybrid electric cars.


January 13, 2015

“Zinc metal plays a critical role in the formation of nanoporous graphene," says researcher David Ji. "During the synthesis, zinc (Zn) is converted into nanoparticles of zinc oxide (ZnO) that serve as substrates with the matched lattice for nanoporous graphene phases to grow from."
“Zinc metal plays a critical role in the formation of nanoporous graphene,” says researcher David Ji. “During the synthesis, zinc (Zn) is converted into nanoparticles of zinc oxide (ZnO) that serve as substrates with the matched lattice for nanoporous graphene phases to grow from.”

WHAT IF WE COULD TURN EXCESS CO2 into a boon for electronics and other industries?

Chemists and engineers at Oregon State University have discovered a way to do just that. David Ji and his research team have captured atmospheric carbon dioxide — a greenhouse gas — and used it to make an advanced, high-value material for energy-storage devices that power everything from defibrillators to hybrid electric cars.

This innovation in nanotechnology won’t soak up enough carbon to solve global warming, the researchers say. However, it will provide an environmentally friendly, low-cost way to make “nanoporous graphene,” a pure form of carbon that’s super-strong and ultra-efficient at conducting heat and electricity. All of these properties give nanoporous graphene a big edge over activated carbon, now used in making commercial supercapacitors — devices that can store energy for rapid release.

Because the materials involved are inexpensive and the fabrication is simple, it has the potential to be scaled up for production at commercial levels.

“There are other ways to fabricate nanoporous graphene, but this approach is faster, has little environmental impact and costs less,” says Ji, an assistant professor of chemistry and lead author on the study, published in Nano Energy with coauthors from Argonne National Laboratory, University of South Florida, National Energy Technology Laboratory and OSU College of Engineering. “The product exhibits high surface area, great conductivity and, most importantly, it has a fairly high density that is comparable to the commercial activated carbons.”

There’s another obvious plus. “The carbon source is carbon dioxide, which is a sustainable resource, to say the least,” Ji notes. “This methodology uses abundant carbon dioxide while making energy storage products of significant value.”

The chemical reaction involves a mixture of magnesium and zinc, a combination discovered for the first time. These are heated to a high temperature along with carbon dioxide to produce a controlled “metallothermic” reaction. The reaction converts the elements into their metal oxides and nanoporous graphene. The metal oxides could later be recycled into their metallic forms to make an industrial process more efficient.

By comparison, other methods to make nanoporous graphene often use corrosive and toxic chemicals, in systems that would be challenging to use at large commercial levels.

“Most commercial carbon supercapacitors now use activated carbon as electrodes, but their electrical conductivity is very low,” Ji says. “We want fast energy storage and release that will deliver more power, and for that purpose the more conductive nanoporous graphene will work much better. This solves a major problem in creating more powerful supercapacitors.”

Dave Stauth is a science writer for OSU’s News and Research Communications group.

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