Structurally decoupled strongly hydrophobic biocathode enables high-performance flexible enzymatic biofuel cells for self-powered sensing

PPy nanowires with ultrathin PTFE coating enable a tri-phase interface for enhanced O 2 transport and electron conduction. • The flexible EBFC achieves 334 μW·cm -2 power density in ambient air with long-term stability and mechanical robustness. • Self-powered glucose biosensing achieves a broad linear range of 1-20 mmol·L -1 with high fidelity and selectivity. Flexible and wearable enzymatic biofuel cells (EBFCs) have garnered considerable attention for their potential in self-powered sensing and portable electronics. However, their overall performance is often severely constrained by the sluggish oxygen reduction reaction (ORR) at the cathode, which stems from the low solubility and slow mass transfer of dissolved oxygen in the liquid phase. Herein, we propose a structural decoupling strategy to design and fabricate a flexible glucose/O₂ EBFC featuring an enhanced air-breathing biocathode. By conformally coating an ultra-thin, low-surface-energy polytetrafluoroethylene (PTFE) layer onto a 3D conductive scaffold of polypyrrole nanowires (PPy NWs) grown on carbon cloth, a robust gas–liquid–solid triple-phase interface is established. This hierarchical architecture significantly accelerates gas-phase oxygen mass transfer without compromising the intrinsic electrical conductivity. Consequently, the assembled device delivers an open-circuit voltage of ~0.8 V and an outstanding maximum power density of ~334 μW·cm −2 in ambient air. Furthermore, by eliminating the cathodic kinetic bottleneck, the EBFC functions as a self-powered glucose sensor, demonstrating a broad and robust linear response (1–20 mmol·L −1 , R 2  = 0.9903) that encompasses severe pathological glycemic levels, alongside high selectivity and stability. These distinctive capabilities position the developed EBFC as a highly promising self-sustaining platform for next-generation smart textiles and continuous wearable health monitoring. Download: Download high-res image (149KB) Download: Download full-size image