The Triboelectric Properties of Ex Situ Transferred Bioinspired Polydopamine Films

Triboelectric nanogenerators (TENGs) are promising for energy harvesting, while biomimetic polydopamine films offer extraordinary mechanical resilience and adhesion. Free-standing polydopamine films are synthesized at the air/water interface, with thicknesses from 12 to 80 nm and lateral sizes over 5 cm², enabling easy electrode transfer. The effect of thickness and performance is examined against four polymers: polytetrafluoroethylene, polystyrene, polymethylmethacrylate, and polydimethylsiloxane, with the highest separation force for the latest. Boric acid functioned as an (anti)oxidation agent, improving polydopamine thickness control, mechanical strength, and adhesion to PDMS, leading to a charge density of up to 1.37 nC cm⁻². This nanoarchitecture enabled a simple TENG with an energy density of 1964.64 ± 144.45 µJ m⁻² and a power density of 78.51 ± 1.93 mW m⁻². Long-term stability is confirmed by monitoring peak-to-peak current over 10 000 contact-separation cycles, stabilizing at ≈0.8 µA. The demonstrated device could power up a microdevice and work as a self-powered pressure sensor. This methodology can be scaled for more efficient polydopamine-based TENGs, including multilayer or flexible nanogenerators.