Interfacial Polarization Engineering in MXene-Polymer Nanofibers for High-Output Triboelectric Nanogenerators

In mechanical energy harvesting and sensing, triboelectric nanogenerators (TENGs) have garnered significant attention for effectively extracting energy from low-frequency, irregular motion and directly transducing it into sensing signals. However, poly(vinylidene fluoride)-based (PVDF-based) TENGs frequently exhibit limitations, including low power density, low output current, and high matched load resistance during operation. Herein, we report a TENG based on MXene, hydroxypropyl methylcellulose (HPMC), and PVDF-HFP composite nanofibers membrane (MHPm) as the negative tribo-layer and Al foil as the counter tribo-layer/electrode for low-frequency mechanical energy harvesting and real-time, ultrasensitive respiratory monitoring. HPMC acts as a synergistic regulator that promotes interfacial interactions among MXene, HPMC, and PVDF-HFP, reduces the coherent stacking scale of MXenes, and facilitates the maintenance of a discrete conductor-polymer-conductor structure, thereby strengthening interfacial polarization and electrical output performance. Under the drive of 70 N and 6 Hz, this device achieves a peak-to-peak (p-p) open-circuit voltage of 1.02 kV, a p-p short-circuit current density of 0.133 A·m^-2, and a peak power density of 27.40 W·m^-2 at a matched load resistance of 20 MΩ, while maintaining a stable current output over 15,000 contact-separation cycles. Moreover, the electrical outputs also provide well-differentiated breathing waveforms, enabling direct self-powered signal acquisition and supporting integrated wearable functionality.