Bifunctional Silver Nanoparticle Cathode in Microbial Fuel Cells for Microbial Growth Inhibition with Comparable Oxygen Reduction Reaction Activity

Abstract

Organic contamination of water bodies in which benthic microbial fuel cells (benthic MFCs) are installed, and organic crossover from the anode to the cathode of membraneless MFCs, is a factor causing oxygen depletion and substrate loss in the cathode due to the growth of heterotrophic aerobic bacteria. This study examines the possible use of silver nanoparticles (AgNPs) as a cathodic catalyst for MFCs suffering from organic contamination and oxygen depletion. Four treated cathodes (AgNPs-coated, Pt/C-coated, Pt/C+AgNPs-coated, and plain graphite cathodes) were prepared and tested under high levels of organics loading. During operation (fed with 50 mM acetate), the AgNPs-coated system showed the highest DO concentration (0.8 mg/L) in the cathode area as well as the highest current (ranging from 0.04 to 0.12 mA). Based on these results, we concluded that (1) the growth of oxygen-consuming heterotrophic microbes could be inhibited by AgNPs, (2) the function of AgNPs as a bacterial growth inhibitor resulted in a greater increase of DO concentration in the cathode than the other tested cathode systems, (3) AgNPs could be applied as a cathode catalyst for oxygen reduction, and as a result (4) the MFC with the AgNPs-coated cathode led to the highest current generation among the tested MFCs.

Recent progress and perspectives in microbial fuel cells for bioenergy generation and wastewater treatment

“…An et al [7] prepared and tested plain graphite cathodes and others coated with platinum/carbon (Pt/C), silver nanoparticles (AgNPs) or Pt/C + AgNPs. Among the MFCs studied, those incorporating a Pt/ C + AgNP electrode presented the worst performance probably due to the negative impact of silver ions (Ag + ) on the microorganisms in the anodic chamber.…”

Behavior of metal ions in bioelectrochemical systems: A review

“…Silver is physicochemically stable as a cathodic catalyst for the long-term operation of BESs, which is catalytically active on ORR, strong against galvanic corrosion and inhibitive to microbes [191]. Due to its unique electronic and catalytic properties, silver has been employed as catalysts or promoters in enzymatic BESs as well as other noble metals.…”

“…Silver nanoparticles (AgNPs) have been explored to act as a cathodic catalyst in BMFCs, which showed high catalytic activity for ORR as well as inhibition of bacterial growth on the cathode electrode. Compared with Pt/Ccoated cathode, the AgNPs-coated cathode produced a higher current due to inhibition of biofilm growth on the cathode and exhibited a lower overpotential [191].…”

Enzymatic Electrosynthesis: An Overview on the Progress in Enzyme- Electrodes for the Production of Electricity, Fuels and Chemicals

“…For example, Au nanoparticles have been used to prepare biocatalytic electrodes for biosensor applications via a codeposition approach with redox enzymes/proteins on electrode supports [112][113][114][115][116][117][118][119][120][121][122][123]. One-dimensional nanostructures such as fibers and tubes have been also studied recently for their potential in nanoelectronic devices.…”