Photosynthesis-inspired dual-mode self-healing coatings: leveraging peony-like ZnO for corrosion interception and energy harvesting

Abstract

Corrosion degradation has a significant impact on the service life of metallic materials, posing critical environmental, safety and related challenges. Inspired by the energy-driven self-healing mechanism of photosynthesis, silane-modified cellulose nanofibers (KMC) and polydopamine (PDA)-functionalized peony-like ZnO (PFZ) are integrated into a vitrimer matrix (PFD) to construct a composite coating on Q235 carbon steel, which is capable of spontaneous healing without artificial intervention. As a photothermal conversion trigger agent, PFZ can autonomously regulate its self-healing performance according to the energy storage status of the coating, toggling between “conservative” and “activated” modes to exhibit dual-mode self-healing behavior. This intelligent adjustment mechanism has realized the efficient utilization of solar energy and fully demonstrated superior environmental adaptability and self-healing ability (with cracks on the coating narrowing within 10 s under simulated sunlight). In addition, PFZ exhibits a unique “multilayered trapping effect” that effectively traps corrosive media, permanently impeding their further diffusion. The enhanced barrier protection grants the coating an ultra-low current density (7.655 × 10⁻¹⁰ A cm⁻²) and corrosion rate (8.899 × 10⁻⁶ mm per year), which are four and three orders of magnitude lower than those of Q235, respectively, representing excellent anti-corrosion performance. This bio-inspired approach offers a promising strategy for developing advanced coatings with sustainable and efficient corrosion protection.