Efficient moisture energy harvesting through electronegativity enhancement and dual-gradient asymmetric structural design

Currently, low counter-ion adsorption due to low surface charge density of solids and slow ion flow due to lack of gradient structure are still the key factors restricting the performance of moisture energy harvesters (MEHs). In this study, an efficient MEH based on wood aerogel is developed through electronegativity enhancement and dual-gradient asymmetric structure design. The negative potential of the internal channel is successfully enhanced by introducing ionization groups, resulting in an electric double layer (EDL) with higher counterion concentration. Meanwhile, the rapid movement of ions is further induced by the dual-gradient of water and ion concentration triggered by the surface porous structure and the asymmetry of the overall ionization groups. At 80 % relative humidity, the device achieved a peak open-circuit voltage of 650 mV and a short-circuit current of 22 μA, approximately 9.1 times the average current of most biomass-based MEHs. In addition, we also designed a forest fire early warning system that is sensitive and can accurately assess the scale of the fire. These groundbreaking findings not only provide innovative ways to develop simple and effective environmental energy harvesting strategies, but also have the potential to expand its application range.