Applications of Nanomaterials in Microbial Fuel Cells: A Review

Abstract

Microbial fuel cells (MFCs) are an environmentally friendly technology and a source of renewable energy. It is used to generate electrical energy from organic waste using bacteria, which is an effective technology in wastewater treatment. The anode and the cathode electrodes and proton exchange membranes (PEM) are important components affecting the performance and operation of MFC. Conventional materials used in the manufacture of electrodes and membranes are insufficient to improve the efficiency of MFC. The use of nanomaterials in the manufacture of the anode had a prominent effect in improving the performance in terms of increasing the surface area, increasing the transfer of electrons from the anode to the cathode, biocompatibility, and biofilm formation and improving the oxidation reactions of organic waste using bacteria. The use of nanomaterials in the manufacture of the cathode also showed the improvement of cathode reactions or oxygen reduction reactions (ORR). The PEM has a prominent role in separating the anode and the cathode in the MFC, transferring protons from the anode chamber to the cathode chamber while preventing the transfer of oxygen. Nanomaterials have been used in the manufacture of membrane components, which led to improving the chemical and physical properties of the membranes and increasing the transfer rates of protons, thus improving the performance and efficiency of MFC in generating electrical energy and improving wastewater treatment.

Nanocomposite use in MFCs: a state of the art review

“…The membrane works as a physical separator, allowing cations to pass from the negative electrode to the positive electrode while preventing oxygen migration in the anode chamber from the cathode compartment. 24,27,45,59,173 MFC membranes must have low resistance, high cation/anion conductivity, high energy recovery, and strong chemical and physical durability to avoid oxygen transfer from the cathode chamber to the anode chamber. 24,27…”

“…24,27,45,59,173 MFC membranes must have low resistance, high cation/anion conductivity, high energy recovery, and strong chemical and physical durability to avoid oxygen transfer from the cathode chamber to the anode chamber. 24,27…”

“…27,59,173,177 Although commercial membranes are often preferred they regularly suffer from oxygen leakage from the cathode to the anode chamber, high costs, substrate crossover, cation transport and ion buildup. 24,178,179 Considering these drawbacks, current efforts focus on the development of novel PEMs which provide better performance. 27,59,180 In this section, PEMs including NMs are discussed.…”

“…The standard materials used to fabricate electrodes and membranes are inadequate to enhance MFC efficiency. 24 The ratio of the PEM surface area to system volume is crucial for achieving maximum power performance. The employment of a nanomaterial with a significant specific surface area will cause the PEM to have a larger surface area.…”

“…In response to such a need, the scientific community recently focused on improving the MFC components using nanomaterials, whose unique physical and chemical properties have profoundly improved their performance. 24–30 Besides providing structural resistance 31 and improving the electron transfer rate through the electrode 32 and membrane proton transfer selectivity, 33 their exceptional volume-to-surface ratio can control the microbial adherence and retention on the electrode surface, thereby optimizing the bacterial anode electron transfer. 34 For the cathodic half-cell, nano-modification can provide sufficient porosity to facilitate oxygen diffusion through its surface, enabling higher rates of oxygen reduction reaction (ORR) and consequently, current generation.…”