Fossil fuel use, ranging from electricity generating power plants to automobiles, pumps billions of tons of greenhouse gases into the atmosphere annually, changing the climate in ways that are likely to be detrimental to future generations.
The rising use of fossil fuels, driven by population growth and rising standards of living across the globe, adds to the urgency of finding a solution to the problem of rapidly increasing atmospheric carbon dioxide, the major greenhouse gas. At Penn State, a team of researchers led by Craig Grimes has come up with an ingenious method of turning captured CO2 into methane, a combustible fuel, using the energy of the sun.
Writing in Nano Letters (Volume 9, 2009, pp 731-737), Grimes and his team describe a highly efficient photocatalyst that can yield significant amounts of methane, other hydrocarbons, and hydrogen in a simple, inexpensive process. The team used arrays of nitrogen-doped titania nanotubes sputter-coated with an ultrathin layer of a platinum and/or copper co-catalyst(s). The titania captures high energy ultraviolet wavelengths, while the copper shifts the bandgap into the visible wavelengths to better utilize the part of the solar spectrum where most of the energy lies. In addition, the thin-walled nanotubes increase the transport ability of the charge carriers by reducing the chance for recombination of the electron with the hole.
The nanotube arrays were placed inside a stainless steel chamber filled with carbon dioxide infused with water vapor. The chamber was then set outdoors in sunlight; after a few hours the team measured the amount of CO2 converted into useful fuels. The results showed 160 µL of methane per hour per gram of nanotubes, a conversion rate approximately 20 times higher than previous efforts done under laboratory conditions using pure UV light.
“Copper oxide and titanium dioxide are common materials,” Grimes says. “We can tune the reaction using platinum nanoparticles or ideally other, less expensive catalysts.” Grimes believes that the conversion process can readily be improved by several orders of magnitude, which could make the process economically feasible.
“You could have a small scale solar condenser and a concentrated source of CO2 in a closed loop cycle to make a portable fuel. It’s a good way of storing energy for when the sun goes down,” he suggests. Inexpensive solar concentrators could improve the process, as the photocatalytic CO2 conversion appears to scale with the intensity of sunlight.
Capturing CO2 at source points, such as fossil fuel (coal, natural gas, etc.)-burning power plants, and turning it into a transportation fuel in a cheap, sunlight-driven process could dramatically improve the economics of CO2 capture. “Then maybe we could figure out how to capture and reuse the CO2 in our vehicles and none of it would go back into the atmosphere,” Grimes proposes.
Future research will look into increasing conversion rates by modifying the co-catalysts and changing the reactor design from a batch reactor to a flow-through photocatalytic design. “We are now reaching for low hanging fruit,” Grimes says. “There is plenty of opportunity for dramatic improvements.”
The article authors are Materials Research Institute scientists Oomman K. Varghese, Ph.D. and Maggie Paulose, Ph.D.; Thomas J. LaTempa, a graduate student in the Department of Electrical Engineering; and Craig A. Grimes, Ph.D., a professor of electrical engineering and materials science and engineering, as well as a faculty member in the Materials Research Institute at Penn State.
Bioinvasion on the rise
15.02.2017 | Universität Konstanz
Litter Levels in the Depths of the Arctic are On the Rise
10.02.2017 | Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung
In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport
Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...
The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.
The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...
Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...
Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".
Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...
13.02.2017 | Event News
10.02.2017 | Event News
09.02.2017 | Event News
20.02.2017 | Materials Sciences
20.02.2017 | Health and Medicine
20.02.2017 | Health and Medicine