Flexible self-standing porous carbon sheet electrodes fabricated via a wet-laid process for bioelectrochemical applications.

Flexible and self-standing carbon electrodes are highly desirable for bioelectrochemical devices operating in or near biological environments. MgO-templated carbon (MgOC) is widely used as a high-surface-area carbon material for fabricating enzyme electrodes; however, its application is largely limited to deposition onto rigid carbon or metal substrates, carbon fabrics, and paper substrates. In this study, we report the fabrication of a self-standing porous carbon sheet electrode via a wet-laid process, a water-based papermaking technique adapted from conventional papermaking. The resulting sheet contained MgOC particles physically immobilized by polymer binders. Various polymers, including biopolymers (cellulose, chitin, and chitosan) and synthetic polymers (poly(vinyl alcohol) and aramid fibrids), were evaluated as binders. Among them, aramid fibrids uniquely enabled the formation of flexible self-standing carbon sheets. By optimizing the carbon-to-aramid ratio, a porous carbon sheet exhibiting high flexibility and stable electrochemical responses was obtained. The optimized porous carbon sheet exhibited a maximum catalytic current density of 11 ± 1 mA cm-2 for glucose oxidation and retained 73 ± 8% of its initial current after 24 h of continuous operation.