Photothermally responsive pervaporation composite membranes with a NH₂-UiO-66 interlayer for high-efficiency desalination

Pervaporation desalination offers a unique solution for high-recovery desalination, yet its integration with photothermal effects remains hindered by inefficient thermal management and the absence of rational interfacial design. This study transcends conventional approaches by engineering an in-situ grown NH₂-UiO-66 interlayer that concurrently functions as a thermal insulator, a hydrophilization agent, and a vapor-transport mediator within a trilayer composite membrane. This multifunctional interlayer enables a paradigm shift: it localizes photothermal energy to drive rapid, low-temperature crosslinking of a PVA-GO separation layer while simultaneously reducing mass-transfer resistance. At an optimized ZrCl₄ precursor concentration of 4 mmol, this rationally designed architecture achieves an exceptional balance of permeability and selectivity, delivering a water flux of 126.93 kg·m⁻²·h⁻¹ with 99.97% salt rejection for 3.5 wt% NaCl at 75 °C. Under solar irradiation, the membrane exhibits a flux enhancement of 22.56% (1 sun) and 44.45% (2 sun) at 25 °C, with fully reversible photo-responsiveness over 12 cycles. Furthermore, the membrane demonstrates high boron rejection (99.67%) in real seawater desalination. By decoupling the traditionally competing demands of membrane fabrication and operation through a single photothermal energy input, this work establishes a generalizable interlayer-engineering strategy for advancing thermally driven separation technologies.