Multifunctional Organic and Inorganic Composite Coating for Outdoor Droplet Energy Collection and Water Quality Monitoring

Droplet energy harvesting has attracted much attention due to its potential advantages in dealing with future energy crises and the dilemmas faced by environmental pollution. However, large‐scale manufacturing of advanced droplet electricity generators that can adapt to harsh environments remains a key challenge. Herein, we reported MoO 3 ‐doped PBA‐fa (P/M) coatings as triboelectric materials for droplet electricity generators using an industrially viable and scalable ultrasonic spray coating method. The optimal P/M‐based droplet electricity generator exhibits a high output current of 100 μA and an excellent voltage of 37 V, which are superior to some conventional polymer‐based droplet electricity generators and presents one to two orders of magnitude enhancement compared to those of common wall coating‐based droplet electricity generators, respectively. Moreover, an outstanding power density of 281.5 mW m −2 is achieved, preceding most polymer‐based droplet electricity generators. The excellent properties should be ascribed to the collaborative contributions of surface potential, the dielectric properties, and hydrophobicity of the friction layer. Additionally, the P/M coating has superior flame retardancy, self‐cleaning, and antibacterial properties, making it an ideal material for outdoor droplet energy harvesting. Furthermore, the P/M‐integrated droplet electricity generator system functioned as a dual‐mode sensor, enabling real‐time monitoring of bacterial concentration in domestic wastewater and pH variations in industrial effluents.