Plant‐Inspired High‐Performance Hydrovoltaic Electricity Generation in Janus Aerogel Fibers with Gradient Nanostructures

Abstract While plant transpiration offers abundant hydrovoltaic energy, its intrinsic non‐directional water transport significantly constrains output efficiency. To overcome this, we developed bioinspired gradient Janus aerogel fibers using multi‐channel microfluidic spinning. These fibers feature asymmetric cellulose density, with a dense outer layer and a sparse inner core, complemented by carbon‐black surface layers. The resulting Laplace pressure gradients synergistically enhance both axial (4.36 mm s ⁻¹ ) and radial (0.38 mm s ⁻¹ ) water transport, thereby amplifying streaming and double‐layer potentials at the carbon–cellulose interfaces. A single 1.5‐cm fiber with a 0.1 cm ² evaporation area achieves an impressiveoutput of 0.6 V and 4500 nA, representing a 4.6‐fold increase in voltage and a 19.7‐fold increase in current compared to natural Musa basjoo leaves exceeding 3000 cm ² in area. Moreover, these fibers sustain over 95% efficiency across diverse conditions (−20 to 60 °C, 10–90% humidity, wind speeds up to 8 m s ⁻¹ ) and can power wearable electronics like watches, light‐emitting‐diodes, and bulbs via sweat‐based energy harvesting when integrated into textiles, showcasing unprecedented scalability for miniaturized hydrovoltaic systems. This research establishes a new paradigm for high‐performance energy harvesting inspired by nature, achieved through structural and material anisotropy engineering.