A Surface-Engineered Antifouling Droplet Triboelectric Nanogenerator with Enhanced Output and Long-Term Stability for Practical Raindrop Energy Harvesting

Droplet-based triboelectric nanogenerators (D-TENGs) offer significant potential for harvesting energy from natural water droplets, yet surface contamination severely restricts their output performance and operational lifetime. To address critical issues such as surface shielding and reduced charge transfer area caused by residual salts (e.g., calcium and magnesium), this study proposes a micronano patterned D-TENG based on fluorosilane-modified silica (FMS-TENG). Utilizing a polydimethylsiloxane substrate, the device features a hydrophobic and antiscaling composite interface constructed via FM-silica fluorination. This interface effectively reduces water affinity and minimizes ionic residue accumulation, thereby maintaining droplet dynamics and ensuring a stable triboelectric output. Experimental results demonstrate that the FMS-TENG achieves a peak power of 7.6 mW, an order of magnitude higher than that of untreated devices. In continuous droplet impact tests spanning 30,000 cycles, the FMS-TENG exhibited only a 10.1% decay, compared to a 77.3% reduction in conventional devices. Additionally, the FMS-TENG possesses self-cleaning capabilities, restoring the original output performance with just eight droplets after sediment contamination. This study presents an effective surface engineering strategy to enhance the reliability and service life of droplet energy harvesters in real-world environments.