Dual catalytic functions of biomimetic, atomically dispersed iron-nitrogen doped carbon catalysts for efficient enzymatic biofuel cells

We report that the performance of enzymatic biofuel cell (EBC) can be boosted by exploiting the dual function of iron- and nitrogen-codoped carbon nanotube (Fe–N/CNT) catalysts. The Fe–N/CNT is directly used as a cathode catalyst for oxygen reduction reaction while it is combined with glucose oxidase (GOx) and polyethylenimine (PEI) to form GOx/PEI/[Fe–N/CNT] for catalyzing the overall oxidation reactions including glucose oxidation reaction at the anode. The cathode employing Fe–N/CNT catalyst shows excellent onset potential and current density (0.29 V and of 0.9 mA cm⁻²). In anode, GOx/PEI/[Fe–N/CNT] shows proper onset potential and current density (0.17 V and 74.3 μA cm⁻²) with the injection of 8 mM glucose solution. More quantitatively, its Michaelis-Menten constant and maximum current density are 139.4 mM and 347.1 μA cm⁻², respectively, and its catalytic activity is well maintained preserving 81.2% of its initial value even after four weeks. The EBC comprising Fe–N/CNT at the cathode and GOx/PEI/[Fe–N/CNT] at the anode exhibits the maximum power density (MPD) of 63 μW cm⁻². This is the first report that demonstrates the possibility of the heme mimicking nanocatalyst as both anodic and cathodic catalysts for EBCs.