Advanced Liquid-Entrapped Nanosurfaces for Optimized Atmospheric Water Harvesting.

Our study addresses the pressing global freshwater scarcity crisis by engineering advanced liquid-entrapped nanosurfaces optimized for highly efficient atmospheric water harvesting (AWH). Through a synergistic approach integrating carbon fiber paper (CFP), hydrothermally synthesized nanoneedles (NNs), and silicone oil liquid entrapment (LE) within NNs, we achieved remarkable improvements in water collection efficiency. While CFP captures fog effectively during AWH, it faces challenges with water-pinning effects, mitigated by NNs' improved droplet-spreading properties, leading to a notable 50% increase in harvesting efficiency. Further enhancements are observed upon silicone oil entrapment within CFP-bearing NNs, resulting in exceptional performance compared to noninfused surfaces. The resultant liquid entrapped nanoneedles (LE-NNs) and liquid entrapped oxidized (LE-ONNs) surfaces exhibit significant fog harvesting capability, achieving an impressive water collection rate of 21.643 ± 0.538 L/m/h, which represents a 4-fold increase compared to CFP alone. This experiment was conducted with a sample area of 0.5 cm. The samples were tilted at different angles to optimize mist contact with the surface, and the humidifier nozzle was positioned approximately 5 cm from the test surface to ensure a minimal fog velocity. Comprehensive analysis of morphological and compositional attributes is conducted by using techniques such as field emission scanning electron microscopy (FESEM), X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray spectroscopy (EDS), and Fourier transform infrared (FTIR) spectroscopy. Leveraging CFP, NNs, or ONNs with LE presents a straightforward and highly effective surface engineering method. This approach holds promise for advancing water collection technologies and addressing global water crises sustainably.