Repeatability of low scan rate cyclic voltammetry in bioelectrochemical systems and effects on their performance

Abstract

Background Cyclic voltammetry (CV) has become a standard tool in the study of bioelectrochemical systems (BES) because it is a nondestructive technique that provides useful information on the electron transfer capacity of these systems. When applied to the large‐surface electrodes typically found in BES, the scan rate must be severely diminished or otherwise the capacitive current masks the faradaic current. Decreasing the scan rate results in an increase in the duration of the experiments, which can lead to a significant alteration of the initial system conditions. Results The repeatability of low scan rate cyclic voltammetry (LSCV) in air cathode microbial fuel cells (AC‐MFCs) operating in batch mode was examined. Consecutive LSCVs at 0.1 mV s−1 were recorded with and without prior renewal of the culture medium. Significant deviations in CV replicates were observed when the medium was not replaced (as high as 40% of maximum intensity). These deviations decreased (<18%) when the medium was refreshed, indicating that significant changes in the culture medium composition occurred during LSCVs. Additional electrochemical tests showed that the peak in the forward scan was probably the result of an accumulation of charge in the anodic system. Conclusion LSCV can affect the response of AC‐MFCs working in batch mode and cast doubt on the repeatability of these experiments, observing differences as high as 40% in maximum intensity. Renewing the culture medium is recommended to improve the repeatability of LSCV replicates. © 2020 Society of Chemical Industry

Combining Geobacter spp. Dominated Biofilms and Anaerobic Digestion Effluents─The Effect of Effluent Composition and Electrode Potential on Biofilm Activity and Stability

“…In contrast to AD, microbial electrochemical technologies (METs) represent novel biotechnological applications that are not yet part of industrial processes . Primary METs rely on electroactive microorganisms (EAMs) acting as bioelectrocatalysts in anodic oxidation or cathodic reduction − (see also eqs S3 and S4). They are based on microbial extracellular electron transfer (EET) that allows connecting the metabolic electron flux with electron flow at electrodes .…”

Unveiling the Mechanism of Enhanced Extracellular Electron Transfer by Polarity Inversion of Bioelectrodes

“…CV was used to determine the electroactivity of EABs after polarity inversion. All the biofilms exhibited a typical sigmoidal shape (Figure ), which has often been reported for EABs in BESs . The CV on the 7th day displayed the highest maximum cathodic current density (reduction peak) of 2.28 A/m 2 , which was 2.85 and 1.82 times that on the 10th (−0.80 ± 0.01 A/m 2 ) and 14th day (−1.25 ± 0.05 A/m 2 ).…”

“…All the biofilms exhibited a typical sigmoidal shape (Figure 2), which has often been reported for EABs in BESs. 29 The CV on the 7th day displayed the highest maximum cathodic current density (reduction peak) of 2.28 A/m 2 , which was 2.85 and 1.82 times that on the 10th (−0.80 ± 0.01 A/m 2 ) and 14th day (−1.25 ± 0.05 A/m 2 ). The CV on the 5th day showed the lowest reduction current density of −0.35 A/m 2 .…”

Protocol for bioelectrochemical enrichment, cultivation, and characterization of extreme electroactive microorganisms

“…Alternatively, different scan rates (higher or lower) can also be used. However, higher scan rates will mask the presence of redox peaks, while the lower scan rates may disrupt the biofilm leading to decreased performance ( Ruiz et al., 2020 ). Low scan rates can also affect the repeatability of the bioelectrochemical experiments.…”