Algae-derived electrodes in bioelectrochemical systems

Abstract

Bioelectrochemical systems (BESs), encompassing electrochemical systems that host biofilms of electroactive microorganisms, are increasingly garnering attention as energy-efficient and environmentally friendly alternatives to conventional bioenergy generation methods. A recent focus in BES research is the utilization of carbon materials derived from biomass, particularly from algae, as electrodes. In this study, we explore the preparation and application of algae-derived carbon (ADC) as both biotic and abiotic electrodes in BES. The production of ADC often involves pyrolysis, resulting in materials with desirable characteristics for bioelectrodes, including high surface area and porous structures. Numerous recent studies have successfully integrated ADC as bioanodes in microbial fuel cells (MFCs), resulting in significant improvements in power generation. Furthermore, ADC has found applications as both aqueous and air cathodes in MFCs, delivering exceptional performance due to the abundance of nitrogen functional groups derived from the substantial protein content in microalgae, which enhances the efficiency of oxygen reduction reaction (ORR). ADC was often applied to BES electrodes by coating powdered material onto conventional carbonaceous electrodes. However, only one study has designed ADC-based free-standing electrodes using certain chemicals to maintain the desired shape, a topic warranting further investigation. Notably, ADC generated from lipid-extracted microalgae residue demonstrated better ORR performance compared to ADC from whole biomass, suggesting the possibility of a more economically feasible algal biorefinery process. As the demand for sustainable technologies continues to grow, the development of ADC-based electrodes promises to facilitate energy-efficient and eco-friendly BES operations.