research team has succeeded in overcoming one major obstacle to a promising
technology that simultaneously reduces atmospheric carbon dioxide and produces
of Illinois chemical and
biological engineering professor Paul Kenis and his research group joined
forces with researchers at Dioxide Materials, a startup company, to produce a
catalyst that improves artificial photosynthesis. The company, in the
Park, was founded by
retired chemical engineering professor Richard Masel. The team reported their
results in Science.
Artificial photosynthesis is the process of converting
carbon dioxide gas into useful carbon-based chemicals, most notably fuel or
other compounds usually derived from petroleum, as an alternative to extracting
them from biomass.
In plants, photosynthesis uses solar energy to convert
carbon dioxide and water to sugars and other hydrocarbons. Biofuels are refined
from sugars extracted from crops such as corn. However, in artificial
photosynthesis, an electrochemical cell uses energy from a solar collector or a
wind turbine to convert carbon dioxide to simple carbon fuels such as formic acid
or methanol, which are further refined to make ethanol and other fuels.
“The key advantage is that there is no competition with the
food supply,” says Masel, a co-principal investigator of the paper and CEO of
Dioxide Materials, “and it is a lot cheaper to transmit electricity than it is
to ship biomass to a refinery.”
However, one big hurdle has kept artificial photosynthesis
from vaulting into the mainstream: The first step to making fuel, turning
carbon dioxide into carbon monoxide, is too energy intensive. It requires so
much electricity to drive this first reaction that more energy is used to
produce the fuel than can be stored in the fuel.
group used a novel approach involving an ionic liquid to catalyze the reaction,
greatly reducing the energy required to drive the process. The ionic liquids
stabilize the intermediates in the reaction so that less electricity is needed
to complete the conversion.
The researchers used an electrochemical cell as a flow
reactor, separating the gaseous carbon dioxide input and oxygen output from the
liquid electrolyte catalyst with gas-diffusion electrodes. The cell design
allowed the researchers to fine-tune the composition of the electrolyte stream
to improve reaction kinetics, including adding ionic liquids as a co-catalyst.
“It lowers the overpotential for carbon dioxide reduction
tremendously,” says Kenis, who is also a professor of mechanical science and
engineering and affiliated with the Beckman Institute for Advanced Science and
Technology. “Therefore, a much lower potential has to be applied. Applying a
much lower potential corresponds to consuming less energy to drive the
Next, the researchers hope to tackle the problem of
throughput. To make their technology useful for commercial applications, they
need to speed up the reaction and maximize conversion.
“More work is needed, but this research brings us a
significant step closer to reducing our dependence on fossil fuels while
simultaneously reducing carbon dioxide emissions that are linked to unwanted
climate change,” Kenis says.