Enzymatic fuel cells (EFCs) are bioelectrochemical devices used to convert chemical energy from organic fuels into electricity. Recently, a novel enzyme immobilization technique has been introduced through the use of microcavity electrodes sandwiching enzymes and redox mediators between two sheets of carbon nanotubes (CNTs), commonly referred to as buckypaper (BP) electrodes. This study evaluates how the choice of CNTs affects the performance of EFCs. Three types of BPs made from CNTs of different lengths (1.5–800 μm), diameters (9.5–60 nm) and defects were studied in terms of wettability, porosity, and permeation efficiency using methylene blue. BPs were then formed into a microcavity electrode architecture trapping bilirubin oxidase (BOx) and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) as redox mediators. The highest catalytic activity noted for mixed CNT BP trapping BOx (I max = −1.46 mA/cm 2 at 0.41 V) highlights the importance of tailored BP design for optimizing the performance of EFCs. • Microcavity electrodes advance enzymatic fuel cell design. • Enzyme and mediator are sandwiched between two sheets of CNT buckypaper. • Physical properties of CNT govern O₂ transport, permeability, and enzyme retention. • Optimized CNT length and BP pore structure improve EFC performance and stability.
Saad et al. (Sun,) studied this question.