Interface-Tailored Janus Nanofibers for High-Performance and Moisture-Wicking Wearable Energy Harvesting

Achieving high electrical output while maintaining reliable performance under humid, skin-contact conditions remains a critical bottleneck for textile-based self-powered sensors. In this work, we develop a Janus nanofiber mat that integrates asymmetric wettability with interfacial polarization modulation to simultaneously regulate moisture transport and enhance triboelectric output. The architecture consists of a hydrophilic PVP/CA layer, a conductive Ag nanowire interlayer, and a hydrophobic F-POSS/P(VDF-TrFE) layer. This multilayer configuration generates simultaneous gradients in pore size and surface energy, forming directional moisture-transport pathways that rapidly dissipate sweat and help stabilize the interfacial triboelectric state. The incorporation of F-POSS enriches polar phases in P(VDF-TrFE) and significantly reduces the surface potential, as revealed by KPFM, thus enhancing tribonegative polarization and improving charge retention capacity. Benefiting from this cooperative interfacial engineering, the Janus device delivers a peak power density of 0.98 W m^-2, high pressure sensitivities of 4.28 VkPa^-1 and 3.14 mAkPa^-1, and maintains significantly improved output retention across 50-100% RH. The textile platform also serves as a soft, skin-conformable pressure sensor capable of discriminating between joint motion and plantar pressure, and directly powers commercial LEDs and capacitors. This study highlights the potential of interfacial polarization engineering within Janus nanofiber systems as a powerful route to achieve breathable and high-output wearable energy harvesters.