A bio-inspired thermo-responsive hydrogel purifier for effective water harvesting in seawater

Solar desalination technology has garnered considerable attention due to its eco-friendliness, sustainability, and cost-efficiency; however, its practical application is impeded by the drawback of low water yield. To address this challenge, we present a reticulated carpet shark-inspired thermo-responsive purification system mimicking the natural water extraction of the root and evaporation–guttation of pneumatophores. The purifier consists of an internal thermo-responsive (TR) hydrogel and external polyamide (PA) membrane. The incorporation of anisotropic micro-layers along with a graphene (GE) filler has markedly improved the hydrogel's directional heat conductivity, facilitating swift heat transfer across the entire purifier. The hydrogel's swelling and collapsing capabilities have been effectively optimized through meticulous component control. Moreover, the hydrogel exhibits an ultrahigh osmotic pressure (12.1 atm), which provides ample power for the PA membrane to efficiently separate water molecules and salt ions from seawater. Consequently, the resultant purifier boasts an ultra-high freshwater yield of 29.99 kg m⁻²·h⁻¹ under one sun's intensity, surpassing previously reported solar-powered water collection systems in the literature while maintaining excellent salt rejection efficiency in seawater. Remarkably, it exhibits exceptional mechanical robustness and operational stability. The findings of this study underscore the immense potential of TR hydrogels for practical applications in solar desalination.