Post-synthetic modification of UiO-type metal-organic framework with Cu²⁺ ions toward fabrication of flexible...

Post-synthetic modification of MOFs refers to the chemical derivatization of MOFs after their synthesis. Incorporating additional metal ions into the framework is an alternative approach to performing post-synthetic modification, which can expand the interlayer spacing in the MOF structure, provide sufficient spaces for the diffusion of electrolyte ions, and also act as a supporting column to hinder crystal collapse during recording cycles. It enhances the conductivity of MOFs, which improves the transport of electrons and ions, resulting in a significant electrochemical performance. In this work, the post-modification of the synthesized UiO-type MOFs is done in two steps, including a functionalization step and complexation with Cu²⁺ ions. The resulting Cu-Modified MOF is used for the first time as an electroactive material to fabricate a flexible supercapacitor electrode (Cu-Modified MOF/CF (carbon felt)). This electrode exhibits the highest specific capacitance (C_SP) of 302.25 F. g^- 1 at ʋ = 0.005 V. s^- 1. Post-synthetic modification enhances the electrochemical behavior, resulting in a C_SP value 6.72 times higher than that of the MOF. Based on the results, post-synthesis modification of MOFs can lead to the fabrication of different types of MOF materials, which will have a prominent impact on the future of these important materials.