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.
Dispersal of Fish Eggs by Water Birds – Just a Myth?
19.02.2018 | Universität Basel
Removing fossil fuel subsidies will not reduce CO2 emissions as much as hoped
08.02.2018 | International Institute for Applied Systems Analysis (IIASA)
Animal photoreceptors capture light with photopigments. Researchers from the University of Göttingen have now discovered that these photopigments fulfill an...
On 15 March, the AWI research aeroplane Polar 5 will depart for Greenland. Concentrating on the furthest northeast region of the island, an international team...
The world’s second-largest ice shelf was the destination for a Polarstern expedition that ended in Punta Arenas, Chile on 14th March 2018. Oceanographers from...
At the 2018 ILA Berlin Air Show from April 25–29, the Fraunhofer Institute for Laser Technology ILT is showcasing extreme high-speed Laser Material Deposition (EHLA): A video documents how for metal components that are highly loaded, EHLA has already proved itself as an alternative to hard chrome plating, which is now allowed only under special conditions.
When the EU restricted the use of hexavalent chromium compounds to special applications requiring authorization, the move prompted a rethink in the surface...
At the ILA Berlin, hall 4, booth 202, Fraunhofer FHR will present two radar sensors for navigation support of drones. The sensors are valuable components in the implementation of autonomous flying drones: they function as obstacle detectors to prevent collisions. Radar sensors also operate reliably in restricted visibility, e.g. in foggy or dusty conditions. Due to their ability to measure distances with high precision, the radar sensors can also be used as altimeters when other sources of information such as barometers or GPS are not available or cannot operate optimally.
Drones play an increasingly important role in the area of logistics and services. Well-known logistic companies place great hope in these compact, aerial...
16.03.2018 | Event News
13.03.2018 | Event News
08.03.2018 | Event News
16.03.2018 | Earth Sciences
16.03.2018 | Physics and Astronomy
16.03.2018 | Life Sciences