Glyn F. Kennell

Microbial fuel cell with a polypyrrole/poly(methylene blue) composite electrode

Different config urations of anodic and cathodic half-cells were incorporated into a microbial fuel cell to determine the effectiveness of a composite electrode. This novel composite electrode consisted of poly(methylene blue) and polypyrrole electrodeposited onto a stainless steel electrode. The novel electrode/immobilized mediator was incorporated into a microbial cathodic half-cell that relied on the microalgae Chlorella vulgaris for photosynthesis, and was a net reducer of carbon dioxide. Similar microbial cathodic half-cells were also examined using electrodes fabricated from graphite and graphite deposited with methylene blue. Results from using these three different electrodes in the microbial cathodic half-cell were examined and compared with the results from others. The electrode using the novel immobilized mediator demonstrated the highest short circuit current density of 65 mA/m 2 when compared with other C. vulgaris systems. Different anodic half-cells were also incorporated into the microbial fuel cell and tested. Anodic half-cells tested included a microbial half-cell containing Saccharomyces cerevisiae and one containing no microbial material and based on purely chemical constituents. In the case of the microbial anodic half-cell, different electrodes, including the novel immobilized mediator/electrode, were tested. It was found that the anodic half-cell performed better with a soluble mediator than an immobilized mediator/electrode. In the case of a fuel cell where both the anodic and cathodic half-cells are microbial, our results demonstrate better performance than previous systems by using a soluble mediator in the anodic half-cell with an immobilized mediator in the cathodic half-cell.