Glucose biofuel cells using bi-enzyme catalysts including glucose oxidase, horseradish peroxidase and terephthalaldehyde crosslinker

Biocatalysts consisting of bi-enzyme of glucose oxidase (GOx) and horseradish peroxidase (HRP) and terephthalaldehyde (TPA) as cross-linker ([(TPA/HRP/GOx)]/PEI/CNT) that have different GOx and HRP mass ratio are developed and their catalytic activity about glucose oxidation reaction and electrical performance evaluated via biofuel cell are characterized. To gain the optimal catalytic structure, current density peak of flavin adenine dinucleotide redox reaction, electron transfer rate, Michaelis-Menten constants, sensitivity and catalytic stability are measured. As a result, [(TPA/HRP/GOx)]/PEI/CNT whose HRP and GOx ratio is 2:5 is determined as the best catalyst. It is ascribed to superior catalytic activity of GOx and H₂O₂ reduction reaction ability of HRP. Regarding electrical performance, polarization curves of enzymatic biofuel cells (EBCs) using the associated catalysts indicate that maximum power density (MPD) of EBC using [(TPA/HRP/GOx)]/PEI/CNT (HRP and GOx ratio of 2:5) is 2.0 ± 0.1 mW·cm⁻², which is the highest of all the tested EBCs. Based on that, it is obvious that the optimal [(TPA/HRP/GOx)]/PEI/CNT induces improvements in catalytic activity and EBC performance due to proper removal of toxic H₂O₂ molecules by HRP, excellent glucose reactivity by GOx and stable bonding of the catalytic structure by TPA.