A Short Overview of Biological Fuel Cells

Abstract

This short review summarizes the improvements on biological fuel cells (BioFCs) with or without ionomer separation membrane. After a general introduction about the main challenges of modern energy management, BioFCs are presented including microbial fuel cells (MFCs) and enzymatic fuel cells (EFCs). The benefits of BioFCs include the capability to derive energy from waste-water and organic matter, the possibility to use bacteria or enzymes to replace expensive catalysts such as platinum, the high selectivity of the electrode reactions that allow working with less complicated systems, without the need for high purification, and the lower environmental impact. In comparison with classical FCs and given their lower electrochemical performances, BioFCs have, up to now, only found niche applications with low power needs, but they could become a green solution in the perspective of sustainable development and the circular economy. Ion exchange membranes for utilization in BioFCs are discussed in the final section of the review: they include perfluorinated proton exchange membranes but also aromatic polymers grafted with proton or anion exchange groups.

Keywords: anion exchange membranes; biological fuel cell; electrochemical performance; enzymatic fuel cell; microbial fuel cell; proton exchange membranes.

Figure 4

Membrane-less enzymatic fuel cell. Reproduced with permission from Ref. [71].

Figure 1

Schematic working of a microbial fuel cell and factors limiting the performance. (1) Anodic catalytic activity, (2) microorganism to electrode electron transfer, (3) load resistance, (4) proton transfer through the membrane to the cathode, and (5) dissolved oxygen concentration and reduction rate at the cathode. Reproduced with permission from Ref. [39].

Figure 2

Micro-sized MFC (a) schematic and (b) digital photograph. Reproduced with permission from Ref. [52].

Figure 3

Microbial Solar Cell (MSC) (A) of which the Plant Microbial Fuel Cell (P-MFC) (B) is a specific type. In the P-MFC, the photosynthetic organisms are plants. Reproduced with permission from Ref. [53].

Figure 5

Enzyme immobilization methods. Reproduced with permission from Ref. [94].

Figure 6

(a) Long side-chain perfluorosulfonic acid Nafion 1100 (n = 6.6) and short side-chain Aquivion 830 (n = 5.5). (b) Sulfonated aromatic polymers. (c) Anion exchange polymers: poly(sulfone trimethylammonium) (PSU-TMA) and poly(phenylene oxide pentyltrimethylammonium) (PPO-PTA).