2,2,6,6-Tetramethylpiperidine-1-oxyl (TEMPO)-Oxidized Cellulose Nanofibril-Reinforced Hydrogels for High-Output, Mechanically Robust Triboelectric Nanogenerators

With the rapid advancement of wearable sensors and the Internet of Things (IoT), self-powered systems have become essential for sustainable, low-maintenance electronics. Triboelectric nanogenerators (TENGs) are promising candidates; however, achieving high electrical output together with mechanical robustness remains challenging. Herein, we report an ultra-tough, stretchable TENG based on a conductive hydrogel reinforced with 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-oxidized cellulose nanofibrils (TOCNFs). The design delivers a dual benefit: abundant carboxyl groups on TOCNFs enhance triboelectric charge transfer and boost electrical output, while TOCNFs form a robust triple cross-linked network that imparts durability. The resulting TENG achieves an open-circuit voltage of 69.4 V, a short-circuit current of 2.8 μA, a power density of 12.15 μW/cm2, a tensile strength of 3.05 MPa at 908% elongation, and a compressive strength of 4.10 MPa at 80% strain, outperforming most reported hydrogel-based TENGs. For sensing, it exhibits a sensitivity of 0.36 V·kPa-1, fast response and recovery times (298/270 ms), and stable operation over 5000 cycles. Additionally, the device powers microelectronics, enables wireless Morse-code communication, and supports self-powered health monitoring. This work resolves the common trade-off between performance and durability in TENG design and provides a versatile platform for self-powered wearable electronics and IoT applications.