Giving Platinum Catalysts a Golden Boost for Fuel Cells
Platinum might outweigh gold in the jewelry market, but as part of an ongoing effort to produce efficient and affordable fuel cells, scientists at the US Department of Energy's (DOE) Brookhaven National Laboratory are studying how gold atoms might enhance the value of the pricier metal. Specifically, they're looking for ways to use gold to prevent the destruction of platinum in the chemical reactions that take place in fuel cells. Brookhaven chemist Radoslav Adzic will describe this research during the 233rd National Meeting of the American Chemical Society at 2 p.m. Central Time (3 p.m. Eastern Time) on Tuesday, March 27, 2007, in room S405A, Level 4, at McCormick Place South, Chicago, Illinois.
Platinum is the most efficient electrocatalyst for accelerating chemical reactions in fuel cells. However, in reactions during the stop-and-go driving of a fuel-cell-powered electric car, the platinum dissolves. In accelerated tests, as much as 45 percent of the catalyst can be lost during five days. "Platinum is by far the best single component catalyst for the oxygen reduction reaction, and we have to find a way to protect it," Adzic said. Under lab conditions that imitate the environment of a fuel cell, Adzic and a team of Brookhaven researchers, including Junliang Zhang, Kotaro Sasaki, and Eli Sutter, added gold clusters to a platinum electrocatalyst, which kept it intact during an accelerated stability test that simulates stop-and-go driving in an electric car.
The details: A fuel cell converts hydrogen and oxygen into water and, as part of the process, produces electricity. Hydrogen is oxidized at the device's anode (the terminal where current flows in) when electrons are released and hydrogen ions are formed; the released electrons supply current for an electric motor. These electrons flow to the cathode (the terminal where current flows out) to reduce oxygen, and in a reaction with hydrogen ions, water, the only byproduct of a fuel cell reaction, is produced. Platinum electrocatalysts are used to speed up the oxidation and reduction reactions involved in this process, but as a result, they, too, are oxidized (lose electrons) and dissolve.
In the unique method used at Brookhaven
, researchers place gold on carbon-supported platinum nanoparticles by displacing a single layer of copper and subject it to several sweeps of voltage. The copper is needed to reduce the charged gold particles to neutral atoms; it then conveniently forms a monolayer of platinum by an adsorption process, the binding of molecules or particles to a surface. Using x-rays as probes at Brookhaven's National Synchrotron Light Source, a scanning transmission microscope at Brookhaven's Center for Functional Nanomaterials, and electrochemical techniques in the laboratory, the scientists can show that less platinum is oxidized with this method. As predicted, during laboratory testing, the platinum electrocatalyst remains stable when under conditions mimicking stop-and-go driving conditions. Next, researchers will test the catalyst in real fuel cells at the DOE's Los Alamos National Laboratory in New Mexico.
"The very promising properties of fuel cells have been known for many decades," Adzic said. "But it's only now that we can look at the activities and qualities of the catalysts and find something stable enough to be used in cars or residential applications."
More Alternative Energy Articles
Department of Energy to Train 75,000 Solar Workers
First Hybrid-Flywheel Energy Storage Plant in Europe announced in Midlands
World's Largest Solar Thermal Power Project at Ivanpah Achieves Commercial Operation
NTU Scientists Make Breakthrough Solar Technology
Wireless Devices Go Battery-Free Using "Ambient Backscatter" from TV and Cellular Transmissions
Harvesting Electricity from the Greenhouse Gas Carbon Dioxide
Maine Project Launches First Grid-Connected Offshore Wind Turbine in the U.S.
University Researcher Making Rechargeable Batteries with Layered Nanomaterials
Vestas 8 MW Offshore Wind Turbine Could Power Up To 3200 Homes
Urban Green Energy and GE Unveil the Sanya Skypump, an Electric-Vehicle Charging Station Equipped with Wind and Solar Power
even more articles...
Suggest an Article for Green Progress