Fe3O4 nanoparticles shell amplify charge-extraction efficiency in Dunaliella photovoltaics

Microbial biophotovoltaics (BPVs) harness photosynthetic microorganisms to convert light energy into electricity, making them highly attractive for renewable energy production. However, current BPVs typically exhibit low power densities, primarily due to inefficient electron transfer processes and the need for close contact and high interfacial area. Here, we propose a novel method of enhancing Dunaliella-based BPVs using Fe3O4 nanoparticle coatings. The Fe3O4-coated Dunaliella cells (DS@Fe3O4) establish intimate contact with the cellular electron transfer machinery and maximize the interfacial area, significantly improving electron transfer efficiency and reducing internal resistance. This approach achieved higher power outputs compared to native Dunaliella BPVs, with an optimal Fe3O4 concentration of 2 mg/mL yielding the best performance. In contrast, SiO2 coatings on Fe3O4 (Fe3O4@SiO2) reduced electron transfer efficiency. These findings demonstrate that Fe3O4 nanoparticle coatings provide a superior method for enhancing bio-electrochemical systems, advancing the application of BPVs for sustainable energy solutions and environmental applications.