Conductive Geopolymers as Low-Cost Electrode Materials for Microbial Fuel Cells

Shifan Zhang; Jürgen Schuster; Hanna Frühauf-Wyllie; Serkan Arat; Sandeep Yadav; Jörg J Schneider; Markus Stöckl; Neven Ukrainczyk; Eddie Koenders

doi:10.1021/acsomega.1c03805

Conductive Geopolymers as Low-Cost Electrode Materials for Microbial Fuel Cells

ACS Omega. 2021 Oct 19;6(43):28859-28870. doi: 10.1021/acsomega.1c03805. eCollection 2021 Nov 2.

Authors

Shifan Zhang¹, Jürgen Schuster², Hanna Frühauf-Wyllie³, Serkan Arat⁴, Sandeep Yadav⁵, Jörg J Schneider⁵, Markus Stöckl², Neven Ukrainczyk¹, Eddie Koenders¹

Affiliations

¹ Department of Materials in Civil Engineering at the Technical University of Darmstadt, Franziska-Braun-Straße 3, 64287 Darmstadt, Germany.
² Department of Electrochemistry, DECHEMA-Research Institute, Theodor-Heuss-Allee 25, 60486 Frankfurt a. M., Germany.
³ Department of Industrial Biotechnology, DECHEMA-Research Institute, Theodor-Heuss-Allee 25, 60486 Frankfurt a. M., Germany.
⁴ Department of Corrosion, DECHEMA-Research Institute, Theodor-Heuss-Allee 25, 60486 Frankfurt a. M., Germany.
⁵ Department of Chemistry at the Technical University of Darmstadt, Alarich-Weiss-Straße 4, 64287 Darmstadt, Germany.

Abstract

Geopolymer (GP) inorganic binders have a superior acid resistance compared to conventional cement (e.g., Portland cement, PC) binders, have better microbial compatibility, and are suitable for introducing electrically conductive additives to improve electron and ion transfer properties. In this study, GP-graphite (GPG) composites and PC-graphite (PCG) composites with a graphite content of 1-10 vol % were prepared and characterized. The electrical conductivity percolation threshold of the GPG and PCG composites was around 7 and 8 vol %, respectively. GPG and PCG composites with a graphite content of 8 to 10 vol % were selected as anode electrodes for the electrochemical analysis in two-chamber polarized microbial fuel cells (MFCs). Graphite electrodes were used as the positive control reference material. Geobacter sulfurreducens was used as a biofilm-forming and electroactive model organism for MFC experiments. Compared to the conventional graphite anodes, the anode-respiring biofilms resulted in equal current production on GPG composite anodes, whereas the PCG composites showed a very poor performance. The largest mean value of the measured current densities of a GPG composite used as anodes in MFCs was 380.4 μA cm^-2 with a standard deviation of 129.5 μA cm^-2. Overall, the best results were obtained with electrodes having a relatively low Ohmic resistance, that is, GPG composites and graphite. The very first approach employing sustainable GPs as a low-cost electrode binder material in an MFC showed promising results with the potential to greatly reduce the production costs of MFCs, which would also increase the feasibility of MFC large-scale applications.