In Situ Functionalization of Carbon Nanotubes With Porphyrin-Based Covalent Organic Frameworks as Electrode Material...

2D covalent organic frameworks (COFs) with redox-active properties and an extended π-conjugated architecture are excellent candidates for energy storage. In this work, we synthesized redox-active, porphyrin-based covalent organic frameworks (MT-COF) by forming amide bonds between 5,10,15-Tris(4-aminophenyl)-20-phenylporphyrin (TPPTri-NH₂) and 5,10,15-Tris(4-carboxyphenyl)-20-phenylporphyrin (TPPTri-COOH). To enhance electrochemical performance, we designed in situ MT-COF wrapping onto carbon nanotubes (SWCNT-NH₂ and MWCNT) via covalent and noncovalent interactions to form SWCNT-MT-COF and MWCNT@MT-COF nanoconjugates, respectively. In a three-electrode setup, MWCNT@MT-COF achieved a potential window of up to 2.2 V, with an impressive specific capacitance of 320.1 F/g at a current density of 0.35 A/g in 0.5 M K₂SO₄. The symmetric supercapacitor cell constructed with MWCNT@MT-COF demonstrated a notable specific capacitance of 45.7 F/g and an energy density of 30.7 Wh/kg, along with a high areal capacitance of 30.5 mF cm^-2 in 0.5 M K₂SO₄. Furthermore, it retained 96.4% of its capacitance after 20,000 Galvanostatic charge-discharge (GCD) cycles at 5 A/g.