An integrated copolymer-based hydrogel system for solar-driven atmospheric water harvesting and electricity...

Sorption-based atmospheric water harvesting (SAWH) presents a promising solution to mitigating global freshwater scarcity, particularly in off-grid regions, as it operates independently of centralized infrastructure. However, developing adsorbents that simultaneously achieve high moisture uptake, rapid desorption kinetics, and long-term durability remains challenging. Here, a novel composite hydrogel adsorbent (PADCL) engineered is reported through the integration of acrylamide (AM) and [2-(methacryloyloxy) ethyl] dimethyl-(3-sulfopropyl) ammonium hydroxide (DMAPS) copolymer network with lithium chloride (LiCl) and photothermal biochar derived from carbonized and acid-washed carboxymethyl chitosan (CMCS-CW). Optimized hydrophilic group distribution and cross-linking architecture alleviate salt-induced densification of conventional hydrogels under high salinity, thereby significantly enhancing overall SAWH performance. Experimental results demonstrate that PADCL exhibits outstanding equilibrium water absorption capacity across a broad humidity range from 30% to 90% relative humidity (RH), ranging from 1.21 to 4.53 g g^-1. Under 1.0 sun irradiation, 86% of the adsorbed water is released within 30 minutes, delivering an integrated power density of 0.59 W m⁻² with thermoelectric modules. Outdoor scale-up evaluations confirm a daily water yield of 5.31 L m^-2, with the harvested water complying with international quality standards and successfully supporting off-grid lettuce cultivation. This work proposes a robust and scalable material design strategy for high-performance atmospheric moisture capture and underscores its potential in addressing the interlinked challenges of water, energy, and food security.