The days of relying on an expensive metal to produce the electrode needed to generate an electrical current for microbial fuel cells may soon be coming to an end.

Researchers from the University of Rochester have made a cheaper and more efficient microbial fuel cell (MFC) that relies on bacteria found in wastewater by developing an electrode using chemically enhanced paper.

Most electrodes used in wastewater have consisted of a rapidly corroding metal or carbon felt, which while being less expensive, is porous and prone to clogging.

The researchers replaced the carbon felt with paper coated with carbon paste, which is a mixture of graphite and mineral oil. The carbon paste is necessary because it attracts electrons emitted by the bacteria.

The researchers created a layered sandwich of paper, carbon paste, a conducting polymer (polyaniline) and a film of the bacteria to create the electrode.

While the new electrode is both cost-effective and easy to produce, it also outperforms the carbon felt.

The electrode had an output of the circuit of 2.24 A m-2 amps per unit area, easily besting the carbon felt anode that had an output of 0.94 A m-2.

“The paper electrode has more than twice the current density than the felt model,” Kara Bren, a professor of chemistry and co-author of the study, said in a statement.

Bren used the bacteria Shewanella oneidensis MR-1, which consumes toxic heavy metal ions in the wastewater and ejects electrons.

The electrons are attracted to the carbon coating on the positive electrode and then flow to the platinum cathode, which needs electrons to carry out its own electrochemical reactions.

 “We’ve come up with an electrode that’s simple, inexpensive, and more efficient,” Lamberg said in a statement. “As a result, it will be easy to modify it for further study and applications in the future.”

The study was published in ACS Energy Letters.