Enhancing the performance of photo-bioelectrochemical fuel cell using graphene oxide/cobalt/polypyrrole composite modified photo-biocathode in the presence of antibiotic

Abstract Photo-bioelectrochemical fuel cell (PBFC) holds a great potential to harvest sustainable electrical energy from wastewater, but low power output limits its applications due to poor electrochemical performance of photo-biocathode. Additionally, antibiotics are ubiquitous in wastewater streams, but little is known regarding their effects on photo-biocathode performance of the PBFC. This study attempted to increase power output of PBFC through improvement of the photo-biocathode performance by modifying the biocathode with graphene oxide/cobalt/polypyrrole (GO/Co/PPy) composite in the presence of oxytetracycline. The GO/Co/PPy composite modified electrode fabricated by one-step electropolymerization method exhibited more excellent catalytic activity toward oxygen reduction compared to Co-alone and Co/PPy modified electrode. The PBFC with GO/Co/PPy composite modified biocathode produced a maximum power density of 19 mW/m 2 , which was almost 4-fold higher than that produced with the bare biocathode (4.9 mW/m 2 ) due to improved bio-electrocatalytic performance of the bicathode by the GO/Co/PPy composite. The maximum power density of the PBFC was further increased 4.6 (105.5 mW/m 2 ), 3.7 (88.7 mW/m 2 ), 2.9 (74.6 mW/m 2 ) and 1.9 (56 mW/m 2 ) fold by exposure to 5, 10, 20, and 50 mg/L OTC, respectively. The further increases in power was due to reduced cathode's charge transfer resistance using degradation products of OTC as mediators and OTC-stimulated growth of species with extracellular electron transfer ability. However, the photosynthesis and growth of alga was negatively affected by OTC concentration higher than 10 mg/L, resulting performance deterioration of bicathode.