Metal‐Based Porous Hygroscopic Hydrogel Toward Efficient Passive Moisture Harvesting and Thermoelectric Generation

ABSTRACT Water and energy scarcity constitute a severe global challenge, particularly acute in arid and remote regions. However, harnessing the ubiquitous atmospheric moisture and solar energy for freshwater production and electricity generation offers a sustainable solution to this challenge. Here, we report a porous hygroscopic hydrogel (CHCL), the CuO and LiCl are mixed with two types of celluloses, forming the moisture adsorption active sites. Benefiting from the precise coordination synergistic effect between the two celluloses, the CHCL has a water uptake of 1.35 g g −1 at 30% relative humidity, and desorb all the water only by one sun illumination. By integrating a real water production system with only 12 g hydrogel, the passive solar‐driven system achieves a water production of 14.3 L kg −1 day −1 under outdoor conditions. Except for freshwater production, the temperature of evaporation surface is higher than bulk, the temperature difference guides a directional charge transfer, building the internal electric field. The constructed thermoelectric generator is capable to generate an open‐circuit voltage of 219.7 mV in a self‐sustained manner.