# Strategies for Enhancing Extracellular Electron Transfer in Environmental Biotechnology: A Review
## 1 Introduction
aeruginosa_ NEJ07R establishes electronic communication with the electrode via PYO adsorption on the carbon surface. The research endeavors to enhance the engagement between redox mediators, microorganisms, and electrodes. This, in turn, may contribute to the advancement of microbial electrochemical technologies that address ecological challenges including, but not limited to, waste valorization, wastewater treatment, and renewable energy generation. Gaining a comprehensive understanding of the electrochemical characteristics exhibited by bio-anodes is crucial to enhancing the overall efficiency and effectiveness of bioelectrochemical systems. Electrochemical impedance spectroscopy (EIS) is frequently employed for the comprehensive investigation of these characteristics. In a study conducted by [PERSON] et al. [19], the authors aimed to measure the properties of bio-anodes, specifically biofilm capacitance, charge transfer, biofilm resistance, and diffusion resistance. To ensure accurate measurements without the influence of electrode capacitance, the researchers utilized Fluorinated Tin Oxide (FTO) as the electrode material for cultivating the electroactive biofilm. FTO has favorable characteristics as an electrode material in the electrochemical investigation of bio-anodes. This is primarily due to its exceptional stability and significantly lower capacitance, which typically ranges in the tens of micro-farads per square centimeter (\(\mu\)F cm\({}^{-2}\)), in contrast to conventional carbon electrodes, such as graphite plates, that possess a capacitance of approximately 1 millifarad per square centimeter (\(\sim\)1 mF cm\({}^{-2}\)). The researchers conducted a study to observe the formation of an electroactive biofilm on FTO (by the utilization of EIS and polarization experiments). The findings of the study demonstrate that the capacitance of the biofilm exhibited a significant rise from an initial value of 2 \(\mu\)F cm\({}^{-2}\) to a final value of 450 \(\mu\)F cm\({}^{-2}\) as the biofilm developed. This observation suggests a correlation between the capacitance and both the current and the total charge generated. The findings of the study additionally indicate that biofilm capacitance can serve as an indicator of the quantity of active biomass present in bioelectrochemical systems. Scanning electrochemical microscopy (SECM) is an additional method that enables the visualization of electrochemical phenomena at the microscale. In the field of bioelectrochemical systems, this technique can be employed to see and analyze the spatial distribution of electroactive species as well as the level of microbial activity on electrode surfaces. SECM offers valuable insights into the electrochemical activity of biofilms, enabling a deeper understanding of the variability in electron transport mechanisms across microbial communities. The technique has also demonstrated its utility in various applications, including the evaluation of membrane permeability, neurotransmitter levels, and intracellular parameters [20]. Furthermore, the utilization of potentiostatic and galvanostatic operation is an electrochemical technique wherein the potential or current, accordingly, is regulated within an electrochemical system. Within the field of bioelectrochemical systems, potentiostatic and galvanostatic techniques are employed to manipulate the electrochemical conditions, modulate the rate of electron transfer, and examine the reaction of microorganisms to varying applied potentials or currents [21; 22]. These electrochemical techniques play an important role in the characterization, optimization, and understanding of the intricate mechanisms associated with extracellular electron transfer in bioelectrochemical systems. Their contributions are crucial in the advancement of microbial electrochemistry and the pragmatic implementation of these systems in the fields of energy generation, wastewater treatment, and environmental monitoring.