Core–Shell MOF@COF Motif Hybridization: Selectively Functionalized Precursors for Titanium Dioxide Nanoparticle-Embedded Nitrogen-Rich Carbon Architectures with Superior Capacitive Deionization Performance

Porous carbon was synthesized by heating the precursor FA within the pores of MOF-5. The resultant carbon displayed a high specific surface area (BET, 2872 m2.g-1) and important hydrogen uptake (2.6 wt % at 760 Torr, -196 degrees C) as well as excellent electrochemical properties as an electrode material for electrochemical double-layered capacitor (EDLC).

The low conductivity of two-dimensional covalent organic frameworks (2D COFs), and most related coordination polymers, limits their applicability in optoelectronic and electrical energy storage (EES) devices. Although some networks exhibit promising conductivity, these examples generally lack structural versatility, one of the most attractive features of framework materials design. Here we enhance the electrical conductivity of a redox-active 2D COF film by electropolymerizing 3,4-ethylenedioxythiophene (EDOT) within its pores. The resulting poly(3,4-ethylenedioxythiophene) (PEDOT)-infiltrated COF films exhibit dramatically improved electrochemical responses, including quantitative access to their redox-active groups, even for 1 μm-thick COF films that otherwise provide poor electrochemical performance. PEDOT-modified COF films can accommodate high charging rates (10–1600 C) without compromising performance and exhibit both a 10-fold higher current response relative to unmodified films and stable capacitances for at least 10 000 cycles. This work represents the first time that electroactive COFs or crystalline framework materials have shown volumetric energy and power densities comparable with other porous carbon-based electrodes, thereby demonstrating the promise of redox-active COFs for EES devices.