Evaluation of Cyanobacteria (Nostoc sp.) immobilized rGO/PPy/ ITO-PET bio-anode for enhanced electrocatalytic and energy conversion for a Photo-bio-electrochemical cell

This study aimed to develop anode with improved performance for potential use in energy applications, particularly in bio-photovoltaic applications. The study comprises the chemical synthesis of a conducting nanocomposite based on reduced graphene oxide and polypyrrole (rGO/PPy) by incorporating PPy into the rGO sheets along with the addition of an aerogel synthesis phase to improve the composite's overall characteristics. A comparative electrochemical analysis was conducted on cyanobacteria (Nostoc sp.) immobilised ITO-PET and modified rGO/PPy/ITO-PET anodes to investigate the photocurrent output of both. The rGO/PPy nanocomposite was further used to develop a cyanobacteria immobilised biofuel cell anode, and the electrochemical characterization of the fabricated bio-anode (rGO/PPy/ITO-PET) was carried out in a lab-made rudimentary electrochemical cell for the bio-electrocatalytic photolysis of water (light) and oxidation of stored organic matter (night). The results show that the modified bio-anode, for the bio-electrocatalytic reaction in the photo-bio-electrochemical cell configuration, attained a maximum current density of 0.132 mA cm^-2 in light, and 0.069 mA cm^-2 in dark at 0.0 V, and 0.375 mA cm^-2 in light, and 0.207 mA cm^-2 in dark at an applied voltage of 1.45 V. Therefore, the electrocatalytic photolysis and oxidation of organic materials were accomplished by the proposed bio-anode via the direct electron transfer mechanism. The amperometric photocurrent response of the developed bio-electrode remained relatively stable for approximately 10 days in the rudimentary designed bio-electrochemical cell. The study demonstrates the potential of rGO/PPy/ITO-PET based bio-electrode for possible application in developing the bio-photovoltaic cells for energy generation.