Structure evolution of air cathodes and their application in electrochemical sensor development and wastewater treatment

Cathode structure and material are the most important factors to determine the performance and cost of single cham-ber air-cathode microbial fuel cell (MFC), which is the most promising type of MFC technology. Since the first air cath-ode was invented in 2004, five major structures (1-layer, 2-layer, 3-layer, 4-layer and separator-support) have been invented and modified to fit new material, improve power performance and lower MFC cost. This paper reviewed the structure evolution of air cathodes in past 18 years. The benefits and drawbacks of these structures, in terms of power generation, material cost, fabrication procedure and modification process are analyzed. The practical applica-tion cases (e.g., sensor development and wastewater treatment) employed with different cathode structures were also summarized and analyzed. Based on practical performance and long-term cost analysis, the 2-layer cathode dem-onstrated much greater potential over other structures. Compared with traditional activated-sludge technology, the cost of an MFC-based system is becoming competitive when employing with 2-layer structure. This review not only provides a detailed development history of air cathode but also reveals the advantages/disadvantages of air cathode with different structures, which will promote the research and application of air-cathode MFC technology.

Automated summary

The cathode structure and material play a crucial role in determining the performance and cost of single-chamber air-cathode microbial fuel cells (MFCs), which are considered the most promising type of MFC technology. This review paper examines the evolution of air cathode structures over the past 18 years, analyzing their benefits and drawbacks in terms of power generation, material cost, fabrication procedure, and modification processes. The practical applications of different cathode structures, such as sensor development and wastewater treatment, are also summarized and analyzed. Based on practical performance and long-term cost analysis, the 2-layer cathode has shown the greatest potential among other structures, making MFC-based systems cost-competitive with traditional activated-sludge technology. This review not only provides a detailed development history of air cathodes but also highlights the advantages and disadvantages of different cathode structures, thus promoting further research and application of air-cathode MFC technology.