Embedding in-plane aligned MOF nanoflakes in silk fibroin for highly enhanced output performance of triboelectric nanogenerators

Embedding active fillers into polymers to construct composite materials is an effective way to enhance the output performance of triboelectric nanogenerators (TENGs). Among various kinds of fillers, 2D fillers provided excellent improvements to the output performance of TENGs due to their large aspect ratios and excellent charge-trapping capability. Herein, we synthesized 2D metal-organic framework nanoflakes (NF-MOF) and embedded them in silk fibroin (SF) to fabricate composite films for TENGs. Owing to their narrow bandgap and high aspect ratio, NF-MOF successfully enhanced the output power density of TENGs. The effect of filler mass ratios and alignment degrees was systematically explored. The maximum instantaneous power density (263 mu W cm(-2)) was obtained by in-plane aligning MOF nanoflakes in the SF matrix with a mass ratio of 0.2 wt%. The proper alignment of NF-MOF in the SF matrix constitutes a network of numerous nanoscale capacitors, providing the composite film with high charge storage capability. The prepared TENG with enhanced output performance was applied to charge commercial capacitors, power small electronics and harvest the physical energy from human motions.