Efficient Fog Harvesting via Synergistic Aerodynamic-Electrostatic Capture in Engineered 3D Janus Conical Arrays

Global water scarcity necessitates the development of efficient atmospheric water harvesting technologies. While fog represents a vast freshwater reservoir, conventional collection via 2D meshes is fundamentally limited by aerodynamic deviation, where low-inertia droplets follow the deviated air streamline, bypassing collector wires. Although electrostatic-assisted methods have been introduced to rectify the droplet trajectory, current mesh-based architectures suffer from significant leakage as fog droplets are frequently drawn through apertures rather than being intercepted. Here, a 3D Janus conical array surface (JCAS) is presented that eliminates this interception gap by synergizing passive aerodynamic trapping with active electrostatic attraction. The JCAS architecture reshapes local airflow to generate internal vortices that decelerate incoming fog, while a corona discharge simultaneously drives charged droplets toward the interior conical walls. Experimental evaluations reveal a stabilized collection rate of 350 g m⁻² min⁻¹, a 66% improvement over state-of-the-art electrostatic meshes. Furthermore, the integration of Janus wettability and a vertical drainage slit prevents surface flooding and ensures continuous operation. By bridging the gap between electrostatic pull and physical interception, this multi-scale approach provides a mechanistic pathway for high-performance fog harvesting, offering a robust solution for decentralized water production in moisture-rich environments.