Despite efforts to brew ethanol as a sustainable automotive fuel substitute for gasoline, the plant-derived alcohol has its drawbacks. A gallon (3.8 liters) of ethanol, for one, contains almost a third less energy than the same volume of gasoline.
So when James A. Dumesic and his fellow chemical engineers at the University of Wisconsin–Madison developed a straightforward way to extract a synthetic fuel from sugar that in many ways surpasses ethanol, the scientific community took notice. Called 2,5-dimethylfuran, or simply DMF, the fuel possesses an energy density equivalent to that of gasoline. It is also insoluble in water and stable in storage. Although chemists have long known about the compound, volume production has been tricky. The new two-step process makes improvements in an intermediate manufacturing step that was a barrier to mass production of DMF.
Beyond finding new alternative fuels for internal-combustion engines, researchers are working on fuel cells that offer another path toward environmentally acceptable power. The key to an effective hydrogen, or proton-exchange membrane (PEM), fuel cell is the microthin coating of platinum particles on the positively charged electrode, where oxygen molecules split into individual charged atoms.
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Chemist Radoslav R. Adzic and his team at Brookhaven National Laboratory have found a way to stop the platinum on the electrode’s surface from oxidizing, which slows down power-generating chemical reactions and also often causes its membrane to degrade, rendering the cell useless. By spraying the electrode with nanoparticles of gold, Adzic’s team made the platinum layer resistant to dissolving and helped it retain most of its original catalytic efficacy.
To produce electricity, most PEM fuel cells must be supplied either with hydrogen or with hydrocarbon compounds that can be catalytically decomposed into hydrogen. Some prototype fuel cells, however, resemble biological cells in that they use chemical enzymes to break down sugars—a special class of hydrocarbon molecules—to generate electrons. Unlike living cells, they typically soon run out of the enzymes necessary to sustain the reaction.
Electrochemist Shelley D. Minteer and her colleague Tamara Klotzbach, both at Saint Louis University, have developed a method to replenish the enzymes in a sugar-powered fuel cell as they degrade with use. The researchers have come up with a polymer wrapping for an enzyme, which keeps the catalytic molecule active for months instead of days.
—Steven Ashley
