Researchers find less expensive way to convert carbon dioxide

April 7, 2015 by Beth Miller
Researchers developed a method to tap solar energy to convert carbon dioxide to different materials.

With an abundance of carbon dioxide being produced worldwide, scientists and engineers are looking for inexpensive ways to turn it into something useful, such as hydrocarbon fuels.

A collaboration of researchers at Washington University in St. Louis and Korea University used nanowires as a catalyst to convert into , which can then be used as a feeder material to create plastics and higher-carbon polymers. The reduction of carbon dioxide is a very energy-intensive process, so the researchers have developed a method to tap to allow the conversion.

Results of the research were published Feb. 27 in ACS Applied Materials & Interfaces.

Parag Banerjee, PhD, assistant professor of materials science in the School of Engineering & Applied Science, works with nanowires created from copper oxide coated with . Banerjee and his lab worked with Pratim Biswas, PhD, the Stanley & Lucy Lopata Professor and chair of the Department of Energy, Environmental & Chemical Engineering.

In this collaboration, the two labs compared two different methods of using nanowires to convert carbon dioxide to another material. Previously, Biswas' lab developed various nanostructured materials for the conversion of carbon dioxide and showed that they could create nano- and meso-structures with titanium dioxide coated with platinum, animated-graphene-encapsulated photocatalysts and others.

"Platinum is expensive, therefore the process would be difficult to scale up," said Banerjee, who runs the Laboratory for Emerging and Applied Nanomaterials (LEAN). "So one has to look into earth-abundant and cheap materials to address conversion of CO2 at the industrial and even global scale."

Banerjee said there are plusses and minuses to both processes.

"The main advantage of the platinum process is that you can go from carbon dioxide to methane in one step," he said. "That takes eight , which is a lot of electrons. The zinc oxide process takes only two electrons, but converts carbon dioxide into carbon monoxide and doesn't require platinum, so there are trade-offs."

To create the catalysts, Banerjee and his lab used copper oxide nanowires, which absorb the light and create electrons and holes. A few atomic layers of zinc oxide on top of the wires allow these electrons to stay on the surface for a long time.

"If you have free electrons, you can initiate chemical reactions," he said. "That's what this catalyst does—it enables electrons to react with gas molecules, which stick to the catalyst surface. Without the zinc oxide added to the copper oxide, this wouldn't work. And using zinc oxide alone, it wouldn't work either, because you need the right material to absorb light, and that's what the copper oxide does. Everything has its own role to play in this catalyst."

Banerjee credits members of his and Biswas' lab, as well as the Photosynthetic Antenna Research Center (PARC) at Washington University, for the successful results.

"Wei-Ning Wang, Fei Wu and Yoon Myung formed an excellent team," Banerjee said. "They showed immense coordination and drive to bring this work to fruition. Research was coordinated across three labs at WashU and one lab in Korea. PARC's support on this project was critical, as well, and having such a facility on campus helps us all do world-class research."

Explore further: Copper nanowires could become basis for new solar cells

More information: "Surface Engineered CuO Nanowires with ZnO Islands for CO2 Photoreduction." ACS Applied Materials & Interfaces. Feb. 27, 2015. DOI: 10.1021/am508590j

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not rated yet Apr 07, 2015
The way this works is a free electron is a stronger oxidizer than well...oxygen, but you need a catalyst to make it work within energy levels that are reasonable, because a hotter electron won't react (too energetic) and a colder electron doesn't have enough energy to react.

"Oxidation" is a misnomer and would be more correctly labelled "electronation," which presently isn't a word at all.

It's the little things that matter. The electrons and so-called "electron holes" control everything.
not rated yet Apr 07, 2015
I wonder how pure the Co2 has to be? If gasses from a fossil plant can be used directly then this could be a useful way to store solar energy.
Bob Osaka
1 / 5 (1) Apr 07, 2015
Plant a tree. Save the platinum for hydrogen fuel cells. There is already more plastic in the oceans than we can deal with, more isn't the answer. Converting carbon dioxide into CO and ultimately methane seems counterproductive to removing carbon from the environment.
4 / 5 (4) Apr 07, 2015
Bob: the idea would be that instead of burning fossil fuels adding more CO2 from rock to air, one could reuse the CO2 already in the air again. Or, if you could put it in a solid form (like a plastic) you could bury it in a landfill (ie CO2 from rock -> CO2 in air -> CO2 in rock again), restoring the atmosphere to something similar to what contemporary life on Earth is used to.
4 / 5 (4) Apr 07, 2015
MR166: you wouldn't even need the solar energy. The leftover heat from the power plant should be sufficient.

Moreover, we are attempting to work on artificial photosynthesis or improved biofuels which *would* be useful ways of capturing and storing solar energy as chemical energy (ie, it's quicker to refuel a liquid fuel into a car than wait for batteries to charge; if you can make the fuel from solar energy + CO2 in the air, so much the better)
not rated yet Apr 07, 2015
" if you can make the fuel from solar energy + CO2 in the air, so much the better"

Since Co2 is trace gas I really doubt that any process can extract it from the air at a reasonable energy cost. Thus it would have to come directly from a power plant.
4 / 5 (4) Apr 07, 2015
Trace gas or no, plants (in the biological sense, not the power generating facilities) seem pretty effective at pulling what *is* in the air out of it and turning it into sugars and other carbohydrates. One can very easily imagine an artificial version of the same.
5 / 5 (1) Apr 07, 2015
making chemicals from power plant co2 sounds ideal and might be profitable.

What chemicals and plastics would you make from carbon monoxide?
Contact Neil Farbstein President of Vulvox Nanobiotechnology Inc about R&D partnerships.
not rated yet Apr 07, 2015
Tasmanian Blue Gum trees are the fastest growing trees ever,
they grow on average 6' a year. They are great for carbon sequestration.
Da Schneib
5 / 5 (1) Apr 12, 2015
Good. One more step along the road. Making the catalyst from inexpensive materials makes it easier to get good compliance in adoption. Producing useful chemicals from it makes it cheaper yet.
Da Schneib
5 / 5 (1) Apr 12, 2015
Tasmanian Blue Gum trees are the fastest growing trees ever,
they grow on average 6' a year. They are great for carbon sequestration.
I'm always tentative about introducing new species into an area. Kudzu springs immediately to mind. http://en.wikiped...d_States It's a major pest in the US South.

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