An eco-friendly photosensitive hydrogel for food security in arid regions

Solar-driven atmospheric water harvesting (SAWH) offers a promising strategy for improving water-use efficiency in greenhouse cultivation. In this study, a low-cost, biodegradable photosensitive hydrogels prepared by polyaspartic acid (PASP) and carbon nanotubes (CNTs) were served to agricultural water management in arid regions. The optimized hydrogel (1.5-CNTs-PASP) exhibited a water uptake of 1.55 g g − 1 within 2.5 h under simulated nocturnal conditions (20 °C, 80% RH) and achieved a rapid desorption rate of 1.53% min − 1 under 800 W m − 2 of irradiation. When integrated into an evaporation-transpiration recycling device (ETRD), the hydrogel enables passive nighttime moisture capture and daytime solar-driven water release, reducing irrigation demand by up to 45% in tomato seedling cultivation without compromising plant growth. Results also revealed the landfilling of post-used hydrogel could enhance soil microbial diversity and enzyme activities, inferring favorable ecological compatibility. Cost analysis revealed $0.08 ~ 0.12 L − 1 of water was realized, suggesting the high practical feasibility of the novel 1.5-CNTs-PASP hydrogel. This work presents an integrated strategy combining efficient water harvesting, agricultural application, and ecological safety for sustainable farming in water-scarce regions.