Oxygen‐Synergized All‐Fiber Hydrovoltaics With Milliamp Output Toward Self‐Powered Breathable Electronics

ABSTRACT Eruptive development of wearable technology has evoked great demand for decentralized energy supplies harvesting ubiquitous environmental stimuli, such as water evaporation. Conventional hydrovoltaic power generators (HPG) collect energy through directional ion migration originating from water gradient in functional materials, while the unsatisfactory electrical output severely hinders the practical applications. Herein, we develop a liquid‐induced high‐performance all‐fiber HPG for sustainable self‐powered electronics by constructing an ion‐enriched storage electrode and coincidently inducing an oxygen‐involved reaction in the solid‐liquid‐gas interface of the functional layer. Taking advantage of the hierarchical structural configuration of HPG, we verify the dual pathway synergistic electricity generation mechanism of hydrovoltaic effect and oxygen‐involved redox through in situ characterization and theoretical calculations. Significantly, the HPG exhibits an impressive power density of 164.5 µW cm −2 , an extraordinary current density of 1.25 mA cm −2 , a high air‐permeability of 428.4 mm s −1 , and an excellent sustainability with high output retention of 88% after 150 cycles of washing, outperforming most of the counterparts. As demonstration of applications, the as‐assembled HPG power supply packs can directly drive various wearable electronics without extra energy storage devices or rectification circuits, demonstrating the great expectation for the development of evaporation energy harvesters and self‐powered wearable electronics.