Structurally Reinforced Silk Fibroin/MXene Flexible Biocomposite Films for Robust Underwater Self-Powered Electronic Systems

The development of fully biodegradable piezoelectric nanogenerators (PENGs) is gaining attention as self-powered implantable and wearable technologies demand energy-harvesting materials that are both eco-friendly and high performing. Silk fibroin (SF) has emerged as a promising bioderived candidate due to its mechanical robustness and biocompatibility; however, its intrinsic piezoelectric output remains limited. This work produces a structurally reinforced silk fibroin (SRSF) biocomposite film, fabricated by incorporating MXene multilayers into the SF matrix, followed by alcohol treatments to induce β-sheet crystallinity, dipole orientation, and interfacial integrity. The fabricated SRSF-PENG device delivered a maximum output voltage of 14.8 V, current of 0.88 μA, and power density of 80.4 μW cm^-3. Recycling studies confirmed that the regenerated device retained nearly 87.8% of its original piezoelectric performance, demonstrating excellent reproducibility. Soil-burial biodegradation tests revealed a rapid decomposition rate exceeding 4.2% week^-1 across a 12 week period. Additionally, environmental stability analyses showed that the SRSF biocomposite film maintained a comparable voltage output under high-humidity (70% RH) and fully underwater conditions, indicating effective MXene protection by the hydrophobic SF network. These findings position SRSF as a sustainable, durable, and high-efficiency material platform for next-generation, self-powered bioelectronic systems.