Improving the power performance of urine-fed microbial fuel cells using PEDOT-PSS modified anodes

M.J Salar-Garcia,F Montilla,C Quijada,E Morallon,I Ieropoulos

doi:10.1016/j.apenergy.2020.115528

Abstract

The need for improving the energy harvesting from Microbial Fuel Cells (MFCs) has boosted the design of new materials in order to increase the power performance of this technology and facilitate its practical application. According to this approach, in this work different poly(3,4-ethylenedioxythiophene)-polystyrenesulfonate (PEDOT-PSS) modified electrodes have been synthesised and evaluated as anodes in urine-fed MFCs. The electrochemical synthesis of PEDOT-PSS was performed by potentiostatic step experiments from aqueous solution at a fixed potential of 1.80 V (vs. a reversible hydrogen electrode) for different times: 30, 60, 120 and 240 s. Compared with other methods, this technique allowed us not only to reduce the processing time of the electrodes but also better control of the chemical composition of the deposited polymer and therefore, obtain more efficient polymer films. All modified anodes outperformed the maximum power output by MFCs working with the bare carbon veil electrode but the maximum value was observed when MFCs were working with the PEDOT-PSS based anode obtained after 30 s of electropolymerisation (535.1 µW). This value was 24.3% higher than using the bare carbon veil electrode. Moreover, the functionality of the PEDOT-PSS anodes was reported over 90 days working in continuous mode.

Highlights

Microbial Fuel Cell (MFC) is an environmentally friendly technology, which relies on the ability of electrogenic bacteria to transform the chemical energy stored in a substrate into electricity
The new design increased the chemical oxygen demand (COD) removal compared to the previous field trial, reaching a value of 92% from half the retention time. These results demonstrate the feasibility of MFCs for generating usable electricity from urine, which opens up the opportunity to generate electricity in remote locations or developing areas where the energy infrastructure is poor
The aim of this work is to analyse the functionality of PEDOT-PSS modified electrodes as efficient and stable anodes in urine-fed MFCs

Summary

Introduction

Microbial Fuel Cell (MFC) is an environmentally friendly technology, which relies on the ability of electrogenic bacteria to transform the chemical energy stored in a substrate into electricity. The interest in MFCs has significantly increased in the last three decades due to this technology contributing positively towards two of the most concerning environmental challenges: increasing global energy needs and waste treatment [1,2,3]. Conventional wastewater treatment techniques are usually energy-consuming and generate waste, which needs to be managed. At the cathode an oxidant is reduced, usually the oxygen in the air, completing the redox reaction. Anodic and cathodic chambers are physically separated by a selective membrane whose main functions are to maintain the distance between the electrodes to avoid the short-circuiting of the system and reduce the substrate losses, oxygen diffusion to the anode and diffusion of substrate or products of its oxidation to the cathode

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