Tandem Atmospheric Water Harvesting and Passive Cooling Enabled by Hygroscopic Biopolymer‐Based Aerogels

Abstract Atmospheric water harvesting (AWH) provides a promising pathway to alleviate global water stress. However, in arid areas, how to solve the local drought problem while making full use of other local wasted energy and improving resource utilization efficiency is still a challenge. Here, salt‐based biodegradable and photothermal aerogels with vertical channels are constructed to efficiently utilize waste heat from photovoltaic (PV) panels for tandem atmospheric water harvesting and passive cooling. Specially, the hydrogen bonding interactions and the ionic cross‐linking of the aerogel porous skeleton together ensure the material's stability. This aerogel has a high‐water adsorption capacity (1.4–5.7 g·g⁻¹ at 30–90% relative humidity (RH)), and solar‐powered water production of up to 1.80 g·g⁻¹·day⁻¹. After integrating aerogels with PV panels, PV waste heat water collection and evaporation processes result in a fresh‐water production of 0.033 kg·m⁻²·h⁻¹, and the PV panel power generation increases by 2.9%. This work demonstrates the great potential of AWH technique combined with passive cooling to fully utilize low‐grade energy, promoting the development of advanced energy‐water cogeneration.