Creation of Gradient Porous Structure and Surface Wettability Engineering of Boron Nanosheet–Silver Nanoparticle Hydrogel for Multifunctional Solar-Driven Water Management

Solar-driven water management such as water purification via evaporation and condensation has gained increasing attention as a promising solution to address the current issues of water and energy scarcity. Herein, a nanocomposite hydrogel incorporating Ag nanoparticle (NP)-loaded boron nanosheets within a polyacrylamide matrix was fabricated, which exhibited excellent solar light absorption efficiency and photothermal conversion capability. Under simulated 1-sun irradiation, the membrane demonstrated an evaporation rate of 4.572 kg m^–2 h^–1 when used with simulated seawater (∼3.5 wt % NaCl), and the cation concentration in the desalinated water was reduced by 3–4 orders of magnitude. The membrane’s excellent performance is attributed to its gradient porous structure with different wettability between the upper and lower surfaces, the plasmonic effect of Ag NPs, and the high water affinity of the boron nanosheets. Additionally, the fabricated membrane showed an excellent pollutant degradation capability and demonstrated potential applications in temperature sensing and thermoelectric generation.