High-Performance Flexible Piezoelectric-Assisted Triboelectric Hybrid Nanogenerator via Polydimethylsiloxane-Encapsulated Nanoflower-like ZnO Composite Films for Scavenging Energy from Daily Human Activities

We successfully synthesized flower-like zinc oxide (ZnO) nanoarchitectures by a chemical precipitation method which is a facile, cost-effective, low-temperature, and quick-synthesis process. Furthermore, these nanoarchitectures were used to design an MWCNT (multiwalled carbon nanotube)/ZnO/PDMS (polydimethylsiloxane) composite film-based hybrid nanogenerator (HNG). Here, the ZnO nanoflowers play an important role in enhancing the piezoelectric and triboelectric potentials of HNG, termed as piezoelectric-assisted triboelectric (PAT)-HNG. The ZnO nanoflowers were employed as the piezoelectric material as well as to enhance the surface roughness of PDMS, which can increase the triboelectric performance. Besides, the MWCNTs were also utilized to evenly distribute the ZnO nanoflowers and also to reduce the internal resistance of PAT-HNG. To maximize the electrical output power of the device, the concentration of ZnO and the amount of MWCNTs were changed and the electrical output performance of PAT-HNG was investigated. As a result, an optimized PAT-HNG with MWCNT/ZnO/PDMS composite film was achieved, which consists of ∼4.95 g of PDMS, 4.8 wt % ZnO, and 0.015 g of MWCNT. The electrical output power of the optimized PAT-HNG was employed to drive 20 commercial light-emitting diodes connected in series. To demonstrate the practical applications of PAT-HNG, it was fixed onto a slipper and efficiently harvested the energy from daily human activities. Consequently, the PAT-HNG device exhibited electrical output voltage/current values of ∼75 V/3.2 μA, ∼150 V/8 μA, and ∼400 V/30 μA, while walking, running, and jumping, respectively.