Catalyst for Cheaper fuel cells

The material could replace platinum in hydrogen vehicles.

Published in Technological Review.com

A new catalyst based on iron works as well as platinum based catalysts for accelerating the chemical reactions inside hydrogen fuel cells. This finding could help make fuel cells for electric cars cheaper and more practical.

• Fuel cell researchers have been looking for cheaper, more abundant alternatives to platinum  which costs between $1,000 to $2,000 an ounce and is mined almost exclusively in just two countries- South Africa and Russia.
• One promising catalyst that uses far less expensive materials - iron, nitrogen and carbon has long been known to promote the necessary reactions, but at rates that are far too slow to be practical.
• Now researchers at the Institute National de la Recherche Scientifique in Quebec have dramatically increased the performance of this type of iron based catalyst. 
• Their material produces 99 amps per cubic centimeter at 0.8 volts, a key measurement of catalytic activity. That is 35 times better than the best nonprecious metal catalyst so far and close to the Department of Energy's goal for fuel cell catalysts: 130 amps per cubic centimeter. 
• The key insight was finding a way to increase the number of active catalytic sites within the material with more sites for chemical reactions, the overall rate of the reactions in the material increases.
• The catalyst is designed to work in proton exchange membrane fuel cells that operates at relatively low temperatures and has high power density.
•  PEM fuel cells use catalysts at two electrodes. One catalyst split hydrogen and other promotes a reaction that combines protons and oxygen to produce water. The second reaction  is more difficult to perform: in conventional fuel cells, platinum is used in both electrodes, but 10 times as much is needed on the water producing side.
• The new catalyst replace platinum on the water producing side, eliminating almost all of the platinum in the fuel cell.
• Many researchers are finding ways to reduce the amount of platinum needed, rather than replacing the material altogether.There are two more significant hurdles remain before it can be practical in fuel cells. 
• First -the catalyst's durability needs to be improved. After 100 hours of testing, the reaction rates decreased by half
• Second- because the catalyst can only work as fast as the reactants are provided, the transport of oxygen and proton into the material needs to be improved.
• The first step toward addressing the material's durability will be closely studying the catalyst to better understand how it works.