A multi-layered interdigitative-electrodes-based triboelectric nanogenerator for harvesting hydropower

Hydropower is the most important and wildly-used renewable energy source in the environment. In this paper, we demonstrate a multi-layered triboelectric nanogenerator (TENG) to effectively harvest the water wave energy. For a single-layered TENG, interdigitive electrodes are incorporated in order to generate multiple electric outputs under water wave or water drop impact. For the collection of water wave energy, a polyurethane (PU) coated copper rod is used to roll back and forth and contact with the polytetrafluoroethylene (PTFE) film covered interdigitative electrodes. The surfaces of the PU and PTFE films are fabricated as porous structures and nanowire arrays, which provide an advantages of large contact area and efficient separation. Under one wave impact, the single-layered TENG composed of nine pairs of interdigitative electrodes can provide nine pulses of electric outputs (each pulsed output voltage is 52V and output current density is 13.8mAm^-2). The instantaneous output power density of a five-layered TENG is 1.1Wm^-2. In addition, the PTFE film covered interdigitative electrodes has been successfully used to harvest water drop energy, whcih can also generate 9 pulses of electric outputs upon one water drop falling. All these results show the developed TENG has a potential to harvest the hydropower of ocean wave and raindrop in the near future.