A new fuel cell catalyst based on iron-carbon nanorods could replace platinum in fuel cell devices that produce and store clean power from the bacterial breakdown of organic matter.

Engineers at the University of Wisconsin-Milwaukee say their nitrogen-enriched iron-carbon nanorod catalyst can replace platinum in what are called microbial fuel cells, providing the same level of efficiency at 5 percent less cost compared with using platinum.

Bacteria in microbial fuel cells produce hydrogen instead of direct current. Nanorods are a kind of nanoscale objects in this case used as catalysts for microbial fuel cells. University of Wisconsin Professor Junhong Chen and Assistant Professor Zhen He tested their nanorod catalyst on microbial fuel cells and on another similar device known as a microbial electrolysis cell.

On the anode electrode of a microbial fuel cell, bacteria feed on organic matter, releasing electrons that create a current. On the cathode side, platinum moderates the oxygen reduction reaction, increasing the efficiency of the cell.

The University of Wisconsin engineers said they incorporated several reactive materials into their catalyst. They attached nitrogen to the surface of a carbon rod and a core of iron carbide.

The pair tested the material against other proposed replacements for platinum – including a similar graphene-based alternative – and found the nanorods' performance superior over a six-month period.

When tested in a microbial fuel cell, the materials also performed better than the graphene-based catalyst material, but was not yet as efficient as platinum.

The researchers will continue to work on their new material to improve its performance in microbial fuel cells. They will also work on developing ways in which the nanorod catalyst can best be mass-produced for use in both MFCs and MECs. – EcoSeed Staff