Fig. 4

Fabrication of TENGs from eco-friendly materials: a CNF-based TENG. (Reproduced with permission from Ref. [37]); b a schematic of the fabrication process for CP biocomposite and interactions between the CA and PEI molecular chains. (Reproduced with permission from Ref. [38]); c a photo of the silk-based TENG and cross-section microscope image of its bottom layer. (Reproduced with permission from Ref. [39]); d the process for preparing IBTENG and the photos of friction layers and fabricated IBTENG. (Reproduced with permission from Ref. [40])