3D multifunctional sponge hydrotalcite-based porous composite hydrogel for solar interfacial steam generation with excellent salt resistance and compression resilience

In recent years, interfacial solar-driven water evaporation technology has attracted widespread attention as an effective method for alleviating water scarcity and water pollution. However, the application of solar evaporators in unpredictable water environments is still limited by mechanical performance and durability. Herein, a multifunctional sponge hydrotalcite-based porous composite hydrogel (PAM/LDH & HCNTs) with salt resistance and compression resilience is prepared by foaming polymerization method. Benefiting from the molecular thermal vibration of CNT and the non-radiative relaxation of LDH, the composite hydrogel exhibits high light absorption (97.59 %) and superior photothermal conversion. Moreover, composite hydrogel shows outstanding compression resilience because of the incorporation of filler materials and the deformability of three-dimensional connecting pore structure. The composite hydrogel demonstrates a competitive evaporation rate of 2.96 kg m- 2 h- 1 under 1 sun. Superhydrophilicity, three-dimensional connecting pores and fast water transport allow rapid brine reflux in the composite hydrogel, thus, ensuring excellent evaporation performance in high brine concentrations. In addition, the composite hydrogel shows an excellent purification for simulated heavy metal ion and dye wastewater. Meanwhile, the composite hydrogel exhibits superhydrophilicity and underwater oleo- phobic properties, indicating potential for oil/water mixtures separation. Therefore, composite hydrogel shows great promise in practical application of desalination and various water environments.