Membraneless enzymatic biofuel cells using iron and cobalt co-doped ordered mesoporous porphyrinic carbon based catalyst

Iron and cobalt co-doped ordered mesoporous porphyrinic carbon (FeCo-OMPC) is employed as the catalyst for both electrodes in membraneless enzymatic biofuel cells (EBCs). FeCo-OMPC is used for catalyzing oxygen redox reaction (ORR), while GOx/[FeCo-OMPC/CNT] is utilized as a catalyst for a series of glucose oxidation reaction (GOR) and hydrogen peroxide oxidation reaction (HPOR). The onset potential of the ORR by FeCo-OMPC is 0.31 V vs. Ag/AgCl, while that of HPOR by FeCo-OMPC/CNT and GOR-HPOR by GOx/[FeCo-OMPC/CNT] are both 0.12 V. The activity of this catalyst is better than previously reported similar catalysts due to the presence of Co species and high metal contents. As a result, the concentration of H₂O₂ generated by GOR is 1.02–1.56 mM when the same glucose concentration as human blood is used. In addition, the EBC using GOx/[FeCo-OMPC/CNT] and FeCO-OMPC shows the maximum power density of 21.3 ± 2.97 μW cm⁻² with open circuit voltage (OCV) of 0.17 ± 0.016 V. These values are significantly higher than those of EBC using the competitive Fe–N/CNT catalyst (0.11 V and 9.6 μW cm⁻²). Moreover, the OCV is close to the expected value by CV (0.19 V), confirming that the FeCo-OMPC catalyst can be used for implantable bioelectronics, such as biosensors and electroceuticals.