Characteristics of Carbon Nanotubes/Graphene Coatings on Stainless Steel Meshes Used as Electrodes for Air-Cathode Microbial Fuel Cells

Abstract

Microbial fuel cells (MFCs) generate low-pollution power by feeding organic matter to bacteria; MFC applications have become crucial for energy recovery and environmental protection. The electrode materials of any MFC affect its power generation capacity. In this research, nine single-chamber MFCs with various electrode configurations were investigated and compared with each other. A fabrication process for carbon-based electrode coatings was proposed, and Escherichia coli HB101 was used in the studied MFC system. The results show that applying a coat of either graphene or carbon nanotubes (CNTs) to a stainless steel mesh electrode can improve the power density and reduce the internal resistance of an MFC system. Using the proposed surface modification method, CNTs and graphene used for anodic and cathodic modification can increase power generation by approximately 3–7 and 1.5–4.5 times, respectively. Remarkably, compared to a standard MFC with an untreated anode, the internal resistances of MFCs with CNTs- and graphene-modified anodes were reduced to 18 and 30% of standard internal resistance. Measurements of the nine systems we studied clearly presented the performance levels of CNTs and graphene applied as surface modification of stainless steel mesh electrodes.

Effect of Electrode Coating with Graphene Suspension on Power Generation of Microbial Fuel Cells

“…Thus, some studies use cultivated bacteria to reduce biological variability as a source of noise. Escherichia coli (E. coil) is a commonly used cultivated bacteria for the study of electrode design [8][9][10].…”

“…Some factors that affect the cost of an MFC include the type of reactor, the membrane separator, the electrode materials, and catalyst materials [11][12][13]. Typical MFC configurations include double-chamber MFCs [8], flat-plate MFCs [6], and single-chamber MFCs [7,9,10,14]. Single-chamber MFC configurations have the advantage of higher power generation and smaller volume than double-chamber MFCs [15].…”

“…Among these factors, electrode materials exert critical effects on the active surface utilization. Metal electrodes, such as stainless steel and titanium, have become a research focus due to their high electrical conductivity, which can effectively collect electrons and reduce ohmic loss [9,20]. Moreover, in MFC systems, electrons are generated by electrochemically active microorganisms at the interfaces between anodic surfaces and microbes [21,22].…”

“…Biofilm is like an electron acceptor of anode, which directly affects substrate metabolism and electronic collection capability [23,24]. For facilitating bacterial attachment and subsequent biofilm formation, three-dimensional metal, for example stainless steel mesh (SSM) [9,[18][19][20][21][22], has been used as an electrode substrate. Electrode surface coatings with nanomaterials have become a reliable and effective approach for enhancing the power output and reliability of MFCs.…”

“…Graphene has been intensively studied as a possible electrode material for MFCs [8][9][10]25] due to its properties, namely high electrical conductivity, surface area, and stability. Anodes modified with graphene can improve the electrode surface area, the adhesion of bacteria, and the efficiency of electron transfer [8].…”