Enhanced Electrical Output for Triboelectric Nanogenerator Based on Cobalt-Doped Zeolitic Imidazolate Framework as a Multifunctional Filler for Negative Tribolayer

Abstract

Developing more efficient triboelectric nanogenerators raises several questions about how to tune the dielectric constant, porosity, and charge-trapping ability of friction layers. Herein, the modification of the standard Ecoflex layer was achieved by the incorporation of pure imidazolate zeolitic frameworks (ZIF-8 and ZIF-67) and modified structures (Cox%/ZIF-8), as a strategy for tuning the dielectric constant of the heterostructure (ZIF/Ecoflex) and the charge transfer rate by progressive incorporation of a cobalt-doping element. As a result, the dielectric constant varied from (2.81 ± 0.28) for pure Ecoflex to (3.29 ± 0.01) for the ZIF-67/Ecoflex composite, while fixed-point Kelvin probe experiments indicate faster charge rearrangement in ZIF-67-based composites. As a consequence of the direct relationship between the transferred charge density and the variation in the dielectric constant of the friction layer, the modification provided by the ZIF incorporation into Ecoflex resulted in an improvement of 58% in the short-circuit current and 170% in the open-circuit voltage measured at 4 Hz, characterizing important findings for cobalt-doping effects in ZIF derivatives applied as a nanofiller in the friction layer for TENGs.