OSU research brings automotive industry closer to clean cars powered by direct ethanol fuel cells
CORVALLIS, Ore. – Alternative energy research at Oregon State University is paving the way for the massive adoption of clean cars powered by direct ethanol fuel cells.
Zhenxing Feng of OSU College of Engineering helped lead the development of a catalyst that solves three key problems long associated with DEFC, as cells are known: low efficiency, cost of catalyst materials, and toxicity of reactions. chemicals inside cells.
Feng and colleagues at Oregon State, University of Central Florida, and University of Pittsburgh found that adding fluorine atoms to palladium-nitrogen-carbon catalysts had a number of effects. positive, especially by keeping high energy density cells stable for nearly 6,000 hours. A catalyst is a substance which increases the rate of a reaction without itself undergoing a permanent chemical change.
The results were published today in Nature Energy.
Cars and trucks powered by gasoline or diesel engines rely on the combustion of fossil fuels, resulting in emissions of carbon dioxide, a greenhouse gas. Motor vehicles are one of the main sources of atmospheric CO2, a major contributor to climate change.
“Combustion engines produce huge amounts of carbon dioxide,” said Feng, associate professor of chemical engineering. “To achieve the goals of carbon neutrality and zero carbon emissions, alternative energy conversion devices using fuel from renewable and sustainable sources are urgently needed. Direct ethanol fuel cells have the potential to replace gasoline and diesel-based energy conversion systems as power sources.
Feng and his associates are in the process of applying for funds to develop prototype DEFC units for portable devices and vehicles.
“If that is successful, we can deliver a device to market in five years,” he said. “With more industrial collaborators, the DEFC vehicle can be implemented in 10 years, hopefully.”
Ethanol, also known as ethyl alcohol, is made up of carbon, hydrogen, and oxygen – its chemical formula is C2H6O – and is the active ingredient in alcoholic beverages. It occurs naturally during the fermentation of sugars by yeasts and can be derived from many sources including corn, wheat, sorghum, barley, sugarcane, and sweet sorghum.
Most of the ethanol produced in the United States is made in the Midwest, most often from corn.
A fuel cell, explains Feng, relies on chemical energy from hydrogen or other fuels to generate electricity cleanly and efficiently. They can use a wide range of fuels and raw materials and can service systems as large as a power plant and as small as a laptop.
“In DEFC technology, ethanol can be generated from a number of sources, especially biomass like sugarcane, wheat and corn,” Feng said. “The advantage of using biological sources to produce ethanol is that plants take up carbon dioxide from the atmosphere. “
Liquid and therefore easy to store and transport, ethanol can provide more energy per kilogram than other fuels such as methanol or pure hydrogen. Additionally, Feng points out, the infrastructure is already in place for the production and distribution of ethanol, making DEFC an attractive option to replace internal combustion engines.
“The first vehicle powered by an ethanol-based fuel cell was developed in 2007,” said Feng. “However, the further development of DEFC vehicles fell considerably behind due to the low efficiency of DEFC, the costs associated with the catalysts and the risk of catalyst poisoning by carbon monoxide produced during the reactions inside. the fuel cell. “
To solve these problems, the research team, which also included Maoyu Wang from OSU and scientists from the University of Southern Science and Technology in China and the Argonne National Laboratory, developed alloy catalysts of high performance palladium which use less precious metal than current palladium catalysts. .
Palladium, platinum and ruthenium are elements appreciated for their catalytic properties but expensive and difficult to obtain.
“Our team has shown that the introduction of fluorine atoms into palladium-nitrogen-carbon catalysts alters the environment around palladium, which improves both the activity and the durability of two important reactions in the cell: the ethanol oxidation reaction and the oxygen reduction reaction, “Feng said. . “The advanced synchrotron X-ray spectroscopy characterizations performed at Argonne suggest that the introduction of fluorine atoms creates a palladium surface richer in nitrogen, which is favorable for catalysis. Durability is improved by inhibiting migration of palladium and decreasing corrosion of carbon.
The National Science Foundation and the US Department of Energy supported this research.