Robust, Scalable, and Triboelectric-Responsive Superhydrophobic Coating for Versatile Smart City Applications.

Self-powered sensing networks are essential for smart city infrastructure, with triboelectric nanogenerators (TENGs) emerging as a promising technology for distributed sensing and energy harvesting. However, widespread TENG implementation is hindered by moisture-induced charge dissipation in urban environments. While superhydrophobic surfaces can mitigate this issue, existing coatings lack sufficient triboelectric properties for effective charge generation, while suffering from mechanical fragility that limits practical deployment. Herein, a triboelectric-responsive superhydrophobic coating (TRSC) is reported that achieves thorough drying within 90 s at room temperature with remarkable cost-effectiveness (<US$1 m-2). The coating exhibits consistent superhydrophobicity (contact angle 157°) and stable electrical output after 500 cycles of mechanical abrasion, tape-peeling, and compression tests. When deployed as smart city sensors, TRSC enables solid-solid contact sensing for traffic monitoring, solid-liquid interfacial energy harvesting from raindrops, and noncontact sensing for human activity detection. The coating maintains performance under 99% relative humidity and shows excellent adhesion on various substrates regardless of surface roughness, microstructure, and geometric complexity. Compatible with automatic spraying systems and conventional equipment, this coating strategy enables large-scale manufacturing to transform existing urban infrastructure into smart sensing networks, marking a significant step toward practical smart city implementation.