Bioinspired nanofiber interfacial layers from corneal stroma for durable aqueous zinc-based electrochromic device

Smart windows that dynamically modulate light transmittance, particularly aqueous zinc (Zn)-based electrochromic windows (AZWs) employing reversible metal electrodeposition, are promising for building energy efficiency due to their high optical contrast and rapid switching. Nevertheless, practical implementation remains hindered by challenges such as Zn dendrite formation, parasitic hydrogen evolution reactions, and inadequate long-term cycling stability. Inspired by the hydration-mediated transparency mechanism of corneal collagen nanofibers, we developed a transparent interlayer of electrospun polyacrylic acid (PAA) nanofibers that minimizes light scattering through its fine fibrous structure and achieves pH-responsive ion regulation via abundant carboxyl groups. By dynamically adapting to changes in the interfacial environment during cycling, it effectively suppresses dendrite growth and side reactions. As a result, the PAA nanofiber-modified Zn symmetric cell demonstrates over 3400 h of dendrite-free operation at 5 mA·cm^-2. When integrated into AZW devices, the PAA nanofiber-modified indium tin oxide electrode achieves a transmittance modulation of 70.2%, fast switching kinetics (14.8 s for tinting and 89 s for bleaching), and efficient photothermal regulation (a 15 °C temperature reduction vs. the bleached state under direct sunlight). This biomimetic strategy offers a promising pathway toward the development of high-performance and durable aqueous AZWs.