Two-dimensional graphene paper supported flexible enzymatic fuel cells

Area of Science:

• Materials Science
• Electrochemistry
• Biotechnology

Background:

• Wearable and implantable biomedical devices require flexible, biocompatible electrode materials for enzymatic biofuel cells (EBFCs).
• Graphene paper presents a promising, low-cost, and freestanding support material for such applications.

Purpose of the Study:

• To investigate the use of two-dimensional graphene paper (2D-GP) as a flexible electrode material for EBFCs.
• To demonstrate the direct immobilization of enzymes on 2D-GP for bioanode and biocathode applications.

Main Methods:

• Fabrication of 2D-GP electrodes via assembly and reduction of graphene oxide (GO) nanosheets.
• Immobilization of glucose dehydrogenase (PQQ-GDH) and bilirubin oxidase (BOx) on 2D-GP.
• Characterization of electrode properties, including mechanical flexibility, conductivity, and enzyme activity.
• Assembly and testing of a glucose/oxygen EBFC.

Main Results:

• 2D-GP electrodes exhibited good mechanical strength, high conductivity, and minimal dependence on bending.
• Immobilized enzymes (PQQ-GDH and BOx) retained their biocatalytic activities.
• The glucose/oxygen EBFC achieved an open circuit voltage of 0.665 V and a power density of 4 μW cm⁻².
• Successful electron transfer mediation for the bioanode and direct electron transfer for the biocathode were observed.

Conclusions:

• Flexible 2D-GP is a viable and effective material for fabricating EBFCs.
• This work represents the first use of flexible graphene papers directly in EBFCs.
• The developed EBFCs show potential for applications in wearable biomedical devices due to their flexibility and facile enzyme immobilization.