Lignin-based polyurethane coatings integrating wear resistance, anti-biofouling, and anti-corrosion performance for durable triboelectric nanogenerators

Triboelectric nanogenerators (TENGs) have shown great potential for harvesting low-frequency mechanical energy in marine environments, yet their practical application is severely limited by biofouling, electrochemical corrosion, and mechanical wear, which degrade interfacial properties and reduce electrical output. Here, we report a multifunctional lignin-based polydimethylsiloxane-polyurethane (lignin-PDMS-PU) coating fabricated via a decoupled stepwise urethane formation strategy. The resulting covalently crosslinked network integrates rigid lignin domains and flexible PDMS segments, achieving enhanced wear resistance, anti-biofouling and anticorrosion performance. Compared with lignin-free PDMS-PU, the optimized coating containing 15 wt% lignin (L15%) reduced the protein (BSA) adsorption by nearly 75% and markedly suppressed bacterial adhesion. During prolonged immersion in 1 M NaCl solution, L15% exhibited an initial low-frequency impedance modulus on the order of 10 11 Ω and remained above 10 9 Ω after 14 days, exceeding the commonly used excellent-protection criterion for organic coatings (>10 9 Ω). The optimized L15% coating achieved approximately 176 V and 65 μW cm⁻ 2 in solid-solid mode with negligible output degradation over 10,000 operation cycles and retained ~81% of its initial output in 4.0 mg mL⁻ 1 BSA solution in liquid-solid mode, compared with only 43% for PDMS-PU, thereby demonstrating improved resistance to protein-induced output attenuation. This work provides a sustainable multifunctional coating strategy for durable TENG systems operating under mechanically abrasive and biologically complex environments.