Sustainable advances in nanostructure-doped polymer hydrogels for fog harvesting: materials innovation, mechanistic insights and emerging applications

Freshwater harvesting is an important strategy to address water scarcity and provide a sustainable solution to such global challenges. In recent years, nanostructure-doped polymer hydrogels (NSPHs) have gained popularity as advanced materials with promising capabilities for effectively enhancing fog-harvesting performance due to their desirable structural, thermal, and surface features. Fog harvesting is an important technique for freshwater collection. This review discusses the progress in fog harvesting; including material innovations, structural design, mechanistic understanding, hydrogel principles, challenges, and advancements in NSPHs.The aim of this study is to provide a comprehensive framework for novel applications in promising research areas, establishing nanoparticle-doped polymer hydrogels as next-generation sustainable fog-harvesting materials. Nanoparticles enhance surface wettability, nucleation sites, surface-to-volume ratios, flexibility, thermal conductivity, solar absorption, and directional water transport, enabling the application of these composites in sustainable agricultural practices, renewable energy production, and smart water management. The study concludes by identifying key research gaps in advanced material performance, scalability, and sustainability on a local scale; intelligent hydrogel-based nanocomposite systems will ultimately address the implications of global water scarcity through fog harvesting.