High-Performance Atmospheric Water Harvesting via Polydimethylsiloxane (PDMS)–Chitosan Surfaces

Water scarcity has emerged as one of the most urgent existential challenges of our era, demanding technologies that are both sustainable and adaptable across diverse climatic conditions. Atmospheric water harvesting (AWH), which captures the Earth’s ubiquitous yet underutilized water vapor, offers a carbon-neutral route to decentralized freshwater generation. In this study, we introduce an eco-friendly drop-casting approach for fabricating high-performance AWH surfaces. By orchestrating the complementary functionalities of PDMS (a hydrophobic polymer) and chitosan (a biopolymer) with intrinsic hydrophilicity, we achieved tunable surface chemistries and microstructures optimized for droplet nucleation, coalescence, and directional transport. Surface characterization using 3D profilometry and FE-SEM revealed finely controlled roughness gradients and hierarchical morphologies that promote rapid condensation and efficient droplet shedding. Among the fabricated architectures, the P@C1 composite demonstrated exceptional fog harvesting efficiency of 2.739 g cm –2 hr –1, outperforming conventional polymeric systems. This unprecedented performance arises from a finely balanced hydrophobic and hydrophilic forces that accelerate droplet formation and release. Fabricated through a low-energy, scalable process, this surface demonstrates how simple, nature-inspired design can transform atmospheric moisture into a sustainable water source, turning a global challenge into an opportunity through the power of intelligent engineering.