Fe³⁺-Coordinated Chitosan-Hydrogel Networks for Highly Deformable and Enhanced Performance Triboelectric Nanogenerators

Triboelectric nanogenerators (TENGs) have attracted a lot of attention recently because they can power wearable electronics and small energy-harvesting devices. However, the use of rigid materials has limited applicability in TENGs, particularly in flexible electronic devices. Hence, to address this challenge, flexible materials are gaining interest as an alternative to conventional rigid materials. This work introduces a hydrogel-based TENG that is easy to fabricate, offers high production efficiency, superior mechanical flexibility, and self-healing capabilities. The incorporation of Fe³⁺ ions into a crosslinked network of chitosan (CHI) and polyacrylic acid (PAA) macromolecular chains significantly enhances the hydrogel's conductivity and the TENG's output performance. Under a 2 N load, a single-electrode mode of hydrogel-TENG (H-TENG) produced output voltage and current of 150 V and 6 µA, respectively. Moreover, the hydrogel retains its good mechanical stretchability (250%), good electrical conductivity, strong adhesion, and robust self-healing ability. After just 5 min of self-healing, this H-TENG device also exhibited effective and sustained self-healing performance of the electrical output signal. Due to its high output voltage, stretchability, self-healing property, and sensitivity to mechanical stimuli, this H-TENG holds great promise as a wearable energy harvesting device and a highly accurate self-powered body motion sensor.