Hydrogen fuel cells are one of the hottest topics in alternative energy. However, switching to a hydrogen economy brings with it a load of difficulties and costs, the biggest of which are how to mass produce, ship, and store the fuel. Thus fuel cell designers have looked to seemingly easier marks like methanol and ethanol.
While methanol fuel cells are relatively proven, with many designs set to enter the small battery market in the next few years, methanol still has the problem of limited supply. Thus researchers are turning to ethanol, which will become increasingly cheap and abundant as cellulosic sources hit commercial-scale production.
The key difficulty, though, is that the bonds between ethanol's two carbon atoms prove too strong to be broken by most catalysts, making such hopes for naught in the past. However, through extensive research scientists at the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory along with researchers from the University of Delaware and Yeshiva University have discovered a solution.
The new catalyst -- a network of platinum and rhodium atoms on carbon-supported tin dioxide nanoparticles -- can split the carbon atoms. Even better, at room temperature it can efficiently oxidize the resulting molecules, yielding hydrogen ions, electrons, and a main byproduct of carbon dioxide. Previous catalysts had produced acetalhyde and acetic acid, two one-carbon molecules which still have hydrogen atoms bonded. Acetalhyde and acetic acid are unsuitable for power generation.
Brookhaven chemist Radoslav Adzic cheers the discovery, stating, "Ethanol is one of the most ideal reactants for fuel cells. It’s easy to produce, renewable, nontoxic, relatively easy to transport, and it has a high energy density. In addition, with some alterations, we could reuse the infrastructure that’s currently in place to store and distribute gasoline."
He adds, "The ability to split the carbon-carbon bond and generate CO2 at room temperature is a completely new feature of catalysis. There are no other catalysts that can achieve this at practical potentials."
In order to analyze how the catalyst behaved, researchers compiled data from x-ray absorption techniques at Brookhaven’s National Synchrotron Light Source and transmission electron microscopy analyses at Brookhaven's Center for Functional Nanomaterials. The result was a better understanding of the synergy in the ternary catalyst that produced such a high chemical activity. This understanding should be useful in various other alternative energy fields, the researchers believe.
Scientists plan to begin producing the new catalyst in sufficient quantities to test fuel cell prototypes, in hopes of scaling up to eventual commercial designs. The resulting cell will need a slight electrical potential to stimulate the catalyst, but as mentioned by the researchers, this potential is quite small, unlike other catalysts available.
The work is detailed in a paper in the online journal Nature Materials.
The research was funded by the Office of Basic Energy Sciences within DOE’s Office of Science.
quote: The Transmisson Efficieny is what really kills the IC in comparison to Fuel Cell. Electrical Drive trains are .8-.9 efficient, whereas most mechanical ones are .6-.7
quote: a network of platinum and rhodium atoms on carbon-supported tin dioxide nanoparticles