Casting-Derived PVA/PDMS Janus Membranes with Stable Photothermal Conversion for Solar Desalination

Abstract Solar photothermal conversion enables water evaporation and purification through localized interfacial heating, offering a sustainable approach for solar energy utilization. However, integrating efficient solar harvesting, continuous water transport, and structural support within a simply fabricated membrane remains challenging. In this study, a casting-derived Janus bilayer photothermal membrane was developed by integrating a hydrophilic PVA/FeCo@C/CNTs/ACNTs photothermal layer with a hydrophobic PDMS/ZnO nanorod supporting layer. The multicomponent FeCo@C/CNTs/ACNTs photothermal layer provides strong broadband solar absorption and efficient photothermal conversion, while the PVA matrix facilitates continuous water transport through swelling-assisted hydration. Meanwhile, the PDMS/ZnO nanorod layer provides mechanical support for the PVA-based photothermal layer and contributes to the structural integrity of the bilayer membrane during interfacial evaporation. Under 1.5 sun irradiation, the membrane surface temperature reached 83.7 °C, while an evaporation rate of 1.618 kg·m–2·h–1 was achieved under 1 sun irradiation. In addition, the membrane demonstrated effective performance in solar-driven seawater desalination and dye-containing water purification, highlighting its potential for solar-driven water-treatment applications.