Abstract
The potential of the use of zirconium, an abundant and less expensive element, as a non-platinum catalyst of the cathode in microbial fuel cells (MFCs) was studied. The oxygen reduction reaction (ORR) activity of various cathodes made from three kinds of zirconium-based materials (ZrO2, ZrCN, and ZrCNO) was evaluated under the operating conditions of MFC. Only ZrCNO catalyst exhibited ORR. Manipulation of parameters of the preparation conditions of the ZrCNO cathode (proportion of Ketjenblack, amount of Nafion, and coating amount of catalyst ink) improved the ORR activity about seven- to twenty-twofold, which was equivalent to about 26 − 29% of the activity of a platinum cathode. The ZrCNO cathode having the highest ORR activity was built into a MFC, which was then used in treating synthetic wastewater. The maximum current density attained was 0.58 W/m2, which is more than two fifths of the density achieved by a platinum cathode. Stable current density maintained by the MFC over about four weeks has made ZrCNO a promising non-platinum material for a cathode catalyst of MFCs.
