Application of gas diffusion electrodes in bioeconomy: An update

Abstract

The transition of today's fossil fuel based chemical industry toward sustainable production requires improvement of established production processes as well as development of new sustainable and bio-based synthesis routes within a circular economy. Thereby, the combination of electrochemical and biotechnological advantages in such routes represents one important keystone. For the electrochemical generation of reactants from gaseous substrates such as O2 or CO2, gas diffusion electrodes (GDE) represent the electrodes of choice since they overcome solubility-based mass transport limitations. Within this article, we illustrate the architecture, function principle and fabrication of GDE. We highlight the application of GDE for conversion of CO2 using abiotic catalysts for subsequent biosynthesis as well as the application of microbial catalysts at GDE for CO2 conversion. The reduction of oxygen at GDE is summarized for the application of oxygen depolarized cathodes in microbial fuel cells and generation of H2O2 to drive enzymatic reactions. Finally, engineering aspects such as scale-up and the modeling of GDE-based processes are described. This review presents an update on the application of GDE in bio-based production systems and emphasizes their large potential for sustainable development of new pathways in bioeconomy.