Agricultural waste-derived moisture-absorber for all-weather atmospheric water collection and electricity generation

Harvesting water and energy from ambient environment promises to relieve the worldwide fresh-water scarcity and energy shortage. The fabrication of well-designed materials for atmospheric water harvesting (AWH) requires highly-technical skills, hampering practical applications in isolated regions or after natural disasters. Herein, we report an efficient moisture absorber from waste corn stalk for AWH and for concurrent electricity generation. The sample can adsorb water at capacities of 0.46–1.84 kg kg−1 under relative humidity of 20%–80%. Moreover, with surface modification using commercial carbon ink, a corn stalk slice (3 cm × 1 cm × 0.2 cm) can output a stable open-circuit voltage of ~0.6 V in the air. Density functional theory calculations reveal that the oxygen groups in the carbon ink contribute to the power generation in the corn stalk. When connected in series, corn stalk slices can directly power an electronic calculator. This study contributes to the development of practical strategies to address issues in the water-waste-energy nexus.