Construction of efficient bioelectrochemical devices: Improved electricity production from cyanobacteria (Leptolyngbia sp.) based on π‐conjugated conducting polymer/gold nanoparticle composite interfaces

In this study, gold electrodes (GE) were coated with conducting polymers to obtain a high photocurrent using cyanobacteria from a novel bioelectrochemical fuel cell. For this purpose, 4‐(4H‐ditiheno[3,2‐b:2',3'‐d]pyrol‐4‐yl) aniline and 5‐(4H‐dithieno[3,2‐b:2',3'‐d]pyrol‐4‐yl) napthtalane‐1‐amine monomers were coated on GE by performing an electropolymerization process. After that, gold nanoparticles (AuNP) were specifically modified by 2‐mercaptoethane sulfonic acid and p‐aminothiophenol to attach to the electrode surface. The conducting polymers GE coat was modified with functionalized AuNP using a cross‐linker. The resulting electrode structures were characterized by cyclic voltammetry and chronoamperometry under on‐off illumination using a fiber optic light source. Cyanobacteria Leptolyngbia sp. was added to the GE/conducting polymer/AuNP electrode surface and stabilized by using a cellulose membrane. During the illumination, water was oxidized by the photosynthesis, and oxygen was released. The released oxygen was electrocatalytically reduced at the cathode surface and a 25 nA/cm 2 photocurrent was observed in GE/ Leptolyngbia sp. After the electrode modifications, a significant improvement in the photocurrent up to 630 nA/cm 2 was achieved.