Water-Triboelectrification-Complemented\nMoisture Electric\nGenerator

Energy\nharvesting from ubiquitous natural water vapor based on\nmoisture electric generator (MEG) technology holds great potential\nto power portable electronics, the Internet of Things, and wireless\ntransmission. However, most devices still encounter challenges of\nlow output, and a single MEG complemented with another form of energy\nharvesting for achieving high power has seldom been demonstrated.\nHerein, we report a flexible and efficient hybrid generator capable\nof harvesting moisture and tribo energies simultaneously, both from\nthe source of water droplets. The moisture electric and triboelectric\nlayers are based on a water-absorbent citric acid (CA)-mediated polyglutamic\nacid (PGA) hydrogel and porous electret expanded polytetrafluoroethylene\n(E-PTFE), respectively. Such a waterproof E-PTFE film not only enables\nefficient triboelectrification with water droplets' contact but\nalso\nfacilitates water vapor to be transferred into the hydrogel layer\nfor moisture electricity generation. A single hybrid generator under\nwater droplets' impact delivers a DC voltage of 0.55 V and a\npeak\ncurrent density of 120 μA cm<sup>–2</sup> from the MEG,\ntogether with a simultaneous AC output voltage of 300 V and a current\nof 400 μA from the complementary water-based triboelectric generator\n(TEG) side. Such a hybrid generator can work even under harsh wild\nenvironments with 5 °C cold and saltwater impacts. Significantly,\nan optical alarm and wireless communication system for wild, complex,\nand emergency scenarios is demonstrated with power from the hybrid\ngenerators. This work expands the applications of water-based electricity\ngeneration technologies and provides insight into harvesting multiple\npotential energies in the natural environment with high output.