A leaf-mimic rain energy harvester by liquid-solid contact electrification and piezoelectricity

Previous droplet-based electricity generator has made breakthroughs in efficient water energy harvesting through taking advantage of the contact electrification, however, the kinetic energy of water remains to be tapped into. In this work, we develop a leaf-mimic rain energy harvester (REH) that allows for the collection of electrostatic and kinetic energy simultaneously based on the synergy of the liquid-solid contact electrification and the piezoelectric effect. Impinged by a water droplet, the REH generates a boosted transferred charge value (101 nC) and high output power density (82.66 W m⁻²). We also show that such performances enable the construction of self-charged wireless sensor systems with continuous operational capability. The REH is also low-cost and facile for fabrication, paving a new way towards high-efficiency power generation from raindrops as well as other water sources.