Aug 21 2007
In an effort to develop alternative energy sources such as fuel cells and solar fuel from "artificial" photosynthesis, scientists at the U.S. Department of Energy's Brookhaven National Laboratory are taking a detailed look at electrons - the particles that set almost all chemical processes in motion.
Electron transfer plays a vital role in numerous biological processes, including nerve cell communication and converting energy from food into useful forms. It's the initial step in photosynthesis as well, where charges are first separated and the energy is stored for later use - one of the concepts behind energy production using solar cells. Understanding and controlling the movement of electrons through individual molecules also could allow for the development of new technologies such as extremely small circuits, or help scientists find catalysts that give fuel cells a much-needed boost in efficiency and affordability. Three Brookhaven chemists will discuss how these applications are related to their most recent findings at the 234th National Meeting of the American Chemical Society.
Platinum is the most efficient metal electrocatalyst for accelerating chemical reactions in fuel cells. However, the reactions caused by the expensive metal are slow, and undesired side reactions often degrade the electrode. In an effort to find an affordable alternative with high activity and stability, Brookhaven chemist Ping Liu and her research group are introducing ruthenium oxide to the electronic system. By carefully forming just one thin layer of platinum on a ruthenium-oxide surface, Ping has calculated that the oxidation-reduction reaction (the driving force for fuel cells) happens almost as quickly as with a pure platinum catalyst, while using much less of the pricey metal and preventing its dissolution.
"Theoretically, when there's one monolayer of platinum on ruthenium-oxide, it has very close activity to pure platinum," Liu said. "It's not quite as good, but it's very close. This surface should be one of the alternatives we consider for oxidation-reduction catalysts."
Future research plans include looking for ways to modify the surface, adding other elements or metals, and further reducing the cost by searching for a surface material less expensive than ruthenium oxide.
The research by Muckerman and Liu is funded through the U.S. Department of Energy's Hydrogen Program, which implements the President's Hydrogen Fuel Initiative, a five-year program that began in 2003 to sponsor research, development, and demonstration of hydrogen and fuel cell technologies. Specifically, the funding derived from DOE's Office of Basic Energy Sciences within the Office of Science, which also funds Newton's work.