Directional Oxygen Defect Engineering in Black Phosphorus Aerogel for Flexible and Stable Moisture‐Electric Generators

Abstract The overuse of fossil energy reserves emphasizes the necessity for the advancement of sustainable energy alternatives. Some functional materials have the capacity to directly produce electricity through interactions with ambient humidity, opening up possibilities for self‐powered devices. Black phosphorus possesses exceptional physicochemical properties and ambient stability. Herein, the fabrication of compact and flexible moist‐electric generators is explored by directional surficial oxygen defect engineering in black phosphorus aerogel. Through directional oxygen‐plasma irradiation, a gradient of surficial oxygen defects is imparted onto the porous skeletons of black phosphorus aerogel, leading to spontaneous charge separation and power generation upon exposure to moist atmospheres. In an air environment with a relative humidity of 80%, the as‐fabricated moisture‐enabled electric generator (with an ultrathin thickness of 160 µm) exhibited the capability to generate a voltage of 0.25 V and a current density of 0.16 µA cm⁻². Comparative experiments and the theoretical calculations provided substantiation of the presence of an internal built‐in electric field. Through a straightforward stacking process, the integrated device can generate a stable voltage of 2.1 V. This work paves a new avenue for the development of self‐powered systems aiming at the conversion of atmospheric potential energy into self‐sustainable electrical power for portable applications.