Moisture-Activated, Low-Temperature Regeneratable Hydrogels for Cost-Effective Carbon Dioxide Capture and Water Harvesting

Abstract Effective emission control requires advanced sorbents that operate efficiently under dilute CO2 concentrations and variable humidities with minimized regeneration energy. However, existing sorbent materials typically incur high operational costs. Here, hydrogel sorbents comprising poly(N-isopropylacrylamide) (PNIPAM) with uniformly distributed triethylenetetramine (TETA) capture sites are developed to enable humidity-enhanced carbon capture and low-temperature regeneration. The hydrogel sorbents exhibit a synergistic moisture-activated capture mechanism, achieving ∼4.1 mmol g–1 CO2 uptake with concurrent water uptake of ∼0.6 g g–1 at 5% CO2 inlet and 70% relative humidity. The gel network enhances oxidative stability and enables regeneration at 50 °C within 30 min, representing a substantial reduction in energy demand. Solar- or Joule-heating-powered regeneration prototype devices are demonstrated to maintain robust stability and durability under continuous operation over 50 cycles. Techno-economic and life-cycle assessments reveal that the hydrogel sorbents offer a promising pathway toward economically viable and environmentally sustainable, decentralized CO2 removal coupled with water recovery.