Metal-Organic Frameworks as Multifunctional Materials for Triboelectric Nanogenerators Applied in Self-Charging Power Sources

High Resolution Image Download MS PowerPoint Slide The singular porous structures of metal–organic frameworks (MOFs), with metal ions or clusters as central nodes and organic compounds as ligands, offer a wide range of environmental and energy-based applications. In particular, for prototypes of triboelectric nanogenerators, the versatile role of MOFs enables their use as friction-layer nanofillers and a means to tune the dielectric constant of tribopairs, thereby improving surface charge activity for both tribopositive and tribonegative layers. The functionalization of MOFs with standard electron-donating and -withdrawing groups and the production of composites improve both tribopairs abilities and the device’s performance under high-humidity and high-temperature conditions. Also, strategies for faster charge-transfer rates in self-charging power sources are discussed, with a view to integrating MOF-based supercapacitors into all MOF devices that leverage the outstanding properties of these structures. In this Review, a comprehensive evaluation of strategies for using MOFs and their composites as nanofillers in tribopairs is provided, with a focus on the potential-well interpretation of doping processes in tribopairs and their impact on the overall performance of energy-harvesting devices and the extension in the limit of operation at high relative humidity, characterizing a critical drawback in TENGs based on standard tribolayers and for integrated devices in which the power output at interfaces can be controlled.