Figure 8.

a–c) Vertical contact‐separation‐mode TENGs using pristine PVDF film as triboelectrification layer. Reproduced with permission.^{[ 59 ]} Copyright 2014, Tsinghua University Press and Springer‐Verlag GmbH Germany, part of Springer Nature. d–h) Electrospun PVDF nanofibers‐based TENGs for acoustic energy harvesting. Reproduced with permission.^{[ 60 ]} Copyright 2019, Elsevier. i–k) A coaxial rotatory freestanding TENG with an annular electrospinning PVDF nanofibrous membrane and rotatable Al electrodes as triboelectric materials for wind energy harvesting. Reproduced with permission.^{[ 61 ]} Copyright 2018, Elsevier.