Dense Thiourea–Graphene Oxide Wetting-Resistant Membrane for Photothermal Distillation

Solar-driven membrane distillation (SDMD) shows great prospects in zero-carbon–water desalination. However, the poor wetting resistance of traditional photothermal membranes remains a key challenge to their practical application. Herein, we constructed a wetting-resistant photothermal membrane comprising a thiourea (TU)–graphene oxide (GO) dense photothermal layer and poly(vinylidene fluoride) (PVDF) hydrophobic layer, simultaneously enhancing the membrane wetting resistance and solar-thermal conversion. The GO-TU/PVDF membrane with stable and fine-sized nanochannels (0.58 nm average pore size) formed by the TU-cross-linked GO exhibited 100% resistance to sodium dodecyl sulfate wetting, while the GO/PVDF control shows obvious swelling with enlarged GO nanochannels and severe wetting. In addition, the introduction of TU partially reduces GO to strengthen its photothermal activity, further enhancing the SDMD flux under irradiation. Our work offers a new and efficient strategy to improve the wetting resistance of photothermal membranes, which may guide the development of more stable SDMD and solar evaporation systems to favor practical application.