Optimization of triboelectric energy harvesting from falling water droplet onto wrinkled polydimethylsiloxane-reduced graphene oxide nanocomposite surface

This study investigates the triboelectric energy harvesting phenomenon of falling water droplets on a novel nanocomposite surface, chemically synthesized from reduced graphene oxide (rGO) and polydimethylsiloxane (PDMS) polymer. The prime concern of this work is to synthesize such a triboelectric nanocomposite film, which will pose optimized hydrophobicity along with ameliorated dielectric properties through proper optimization of filler quantity inclusion in PDMS matrix. Therefore, six samples including one pristine PDMS and five nano-composites (PDMS-rGO) have been prepared by varying filler concentration. Optimization has been explained based on determination of several parameters and nano-characterization techniques such as thickness of rGO flakes, thickness of polymer and nanocomposite samples, water contact angles, dielectric properties, triboelectric outputs, FE-SEM, EDX, FTIR, XPS and Raman spectroscopic analyses. After analyzing the outputs of a single electrode mode triboelectric nanogenerator (SEM-TENG) based on Pristine PDMS and nanocomposite samples, it has been found that 0.5 mg rGO incorporated PDMS matrix of 141 mu m thickness revealed highest water contact angle i.e.116.9 degrees. Besides, highest output potential difference (V-OC) of similar to 2 V and close circuit current (I-SC) of similar to 2 nA have been obtained upon contact and separation of rolling water droplet over the same nanocomposite surface. This work demonstrates a unique way to get an optimized thin triboelectric nanocomposite film, which is able to harvest the kinetic energy of a tiny moving water droplet. Hence, we hope that this work may serve as a convenient platform for triboelectric energy harvesting from natural raindrops, fountains or any real-life phenomenon involving the movement of droplet.