Hybrid W-MgF2/graphene photothermal membrane for efficient solar-driven desalination

Abstract

A novel hybrid W-MgF2/Graphene photothermal membrane is developed to enhance the efficiency of self-heated membrane distillation (SHMD) systems. The membrane combines three distinct functional components: plasmonic tungsten for strong solar absorption, hollow MgF2 nanoparticles for broadband light scattering, and a graphene-PMMA layer for efficient thermal conduction and IR absorption. This tripartite architecture enables highly localized heat generation while minimizing radiative losses, surpassing the limitations of conventional single-component systems. The membrane demonstrates over 95.39 % solar absorption across the 0.3？2.5 μm range. Under 1 sun irradiation, the membrane achieves a maximum water flux of 0.938 LMH, representing a 1.9-fold enhancement compared to uncoated membranes, while maintaining an ion rejection rate above 99 %. Additionally, the membrane is fabricated via a scalable, sequential spray-coating method, allowing large-area (50 × 50 cm2) uniform deposition with excellent long-term durability. These findings establish a new materials strategy for efficient and practical solar-driven desalination.