Polydopamine mediator for glucose oxidation reaction and its use for membraneless enzymatic biofuel cells

Polydopamine (PDA) is used as a biocompatible mediator for fabricating glucose oxidase (GOx) based bioanode of enzymatic biofuel cells (EBFCs). Through the autoxidation and polymerization of dopamine monomer, spherical PDA particles are well synthesized, and their chemical and optical characteristics are verified. Although the durability of bioanode including CNT and PDA (CNT/PDA/GOx/Nafion) is poor, when catalyst including polyethyleneimine (PEI) upper layer (CNT/PDA/GOx/PEI/Nafion) is fabricated, CNT/PDA/GOx/PEI/Nafion shows excellent durability. This indicates PEI plays a critical role in suppressing the leaching out of PDA and GOx molecules. By the role of PEI, the anodic current density of CNT/PDA/GOx/PEI/Nafion (142.6 ± 1.98 μA cm⁻² at 0.6 V (vs. Ag/AgCl)) is 17.3 times better than that of CNT/PDA/GOx/Nafion. When maximum power density (MPD) of EBFC using CNT/PDA/GOx/PEI/Nafion is measured, that of EBFC including membrane and platinum-based air–cathode is 552.8 ± 5.4 µW cm⁻², and that of membraneless EBFC including bilirubin oxidase biocathode is 135.2 ± 5.45 μW cm⁻², which is better than that of other reported EBFCs studies. This confirms that the suggested new catalyst is a viable option as bioanode for EBFC.