Energy Harvesting from Atmospheric Humidity by a Hydrogel-Integrated Ferroelectric-Semiconductor System

Direct utilization of abundantly available solar energy is a promising way to create a sustainable society. Here, we report a ferroelectric-semiconductor (BaTiO3@BiVO4) hybrid that uses an effective strategy to enhance charge separation and transfer during water oxidation. The tetragonal BaTiO3 can induce an outward vector of built-in electric field after positive polarization, which aids in increasing the photovoltage and accelerating holes' transfer to BiVO4's surface. A super-hygroscopic metal hydrogel serves as an atmospheric humidity harvester for continuous water supply to the hybrid, where water oxidation takes place. As the hydrogel absorbs moisture from ambient humid air, it functions as a dehumidifying agent and carries water to the photoanode for power generation, being connected in series with a solar cell, further boosting the carrier's mobility. This photoanode-hydrogel and solar-cell intelligent assembly can generate a photocurrent of 0.4 mA/cm(2) with a relative humidity reduction of 12.0% under an illumination of 10 mW/cm(2).