Synthesis and Electrical Property of Graphite Oxide-like Mesoporous N-Carbon Derived from Polyimide-Covalent Organic Framework Templates

Abstract

In this study, two PI-COFs, PI-TAPA-PMDI (twisted triphenylamine node) and PI-TAPB-PMDI (non-twisted triphenylbenzene node), were pelletized (∼10 mm diameter) under 90 MPa and carbonized at 600 °C in argon for 2–50 h. Carbonization produced nitrogen-doped, defective porous carbons with an enhanced electronic conductivity. Electrochemical impedance spectroscopy showed that PI-TAPB-PMDI COF-600 heated for 50 h had significantly lower resistance (Rs≈ 14.14 Ω and Rct≈ 61.66 Ω) compared to shorter heating treatments (Rs≈ 27.70 Ω), indicating improved electron transport and better interaction with a Fe(CN)63–/Fe(CN)64–redox couple system. The XRD patterns verified the crystalline structure of PI-TAPA-PMDI and PI-TAPB-PMDI COFs, which reduces to an amorphous state during the carbonization progress. The XPS and FTIR results confirmed nitrogen incorporation and hydrogen bonding, while Raman and BET analyses revealed superior structural ordering and porosity in the PI-TAPB-PMDI COF compared to PI-TAPA-PMDI, respectively. For PI-TAPB-PMDI COF-600, increasing carbonization time raised BET surface area (up to 510 m2g–1) and promoted mesoporosity, with a pore size of 2.8 nm after 50 h treatment. In summary, PI-TAPB-PMDI COF-600 With a nitrogen content of 0.5% and conductivity of 3.02 × 10–2S cm–1demonstrates strong potential as a high-performance, functionalized graphite oxide-like material for energy storage applications.