Carbon-Based Air-Breathing Cathodes for Microbial Fuel Cells

Abstract

A comparison between different carbon-based gas-diffusion air-breathing cathodes for microbial fuel cells (MFCs) is presented in this work. A micro-porous layer (MPL) based on carbon black (CB) and an activated carbon (AC) layer were used as catalysts and applied on different supporting materials, including carbon cloth (CC), carbon felt (CF), and stainless steel (SS) forming cathode electrodes for MFCs treating urine. Rotating ring disk electrode (RRDE) analyses were done on CB and AC to: (i) understand the kinetics of the carbonaceous catalysts; (ii) evaluate the hydrogen peroxide production; and (iii) estimate the electron transfer. CB and AC were then used to fabricate electrodes. Half-cell electrochemical analysis, as well as MFCs continuous power performance, have been monitored. Generally, the current generated was higher from the MFCs with AC electrodes compared to the MPL electrodes, showing an increase between 34% and 61% in power with the AC layer comparing to the MPL. When the MPL was used, the supporting material showed a slight effect in the power performance, being that the CF is more powerful than the CC and the SS. These differences also agree with the electrochemical analysis performed. However, the different supporting materials showed a bigger effect in the power density when the AC layer was used, being the SS the most efficient, with a power generation of 65.6 mW·m⁻², followed by the CC (54 mW·m⁻²) and the CF (44 mW·m⁻²).

Key findings

• ▸Activated carbon (AC) electrodes generate higher current and power compared to micro-porous layer (MPL) electrodes.
• ▸The supporting material of the cathode electrode has a slight effect on power performance, with carbon felt (CF) being more powerful than carbon cloth (CC) and stainless steel (SS).
• ▸The use of AC electrodes increases power generation by 34-61% compared to MPL electrodes.

Keywords

Identifiers

DOI

10.3390/catal6090127

Journal

Catalysts

Year

2016