A facile approach for tailoring carbon frameworks from microporous to nonporous for nanocarbons

Controlling carbon frameworks of nanocarbons from microporous to nonporous without imposing any additional treatment on a given type of precursor currently remains a great challenge. Here, a facile approach for tailoring different pore characteristics of carbon frameworks for nanocarbons from polypyrrole (PPy) precursors has been achieved based on the significant effect of reaction medium on the conjugation degree of PPy chains. Nanocarbon from PPy synthesized in NaOH solution (CPPy-NaOH) has numerous micropores with a BET surface area up to 482 m² g^-1, which is 10-fold higher than that of nanocarbon with an almost nonporous carbon framework from PPy polymerized in HCl solution (CPPy-HCl). This could be attributed to a distinct difference in the conjugation degree of the PPy chains. A much lower conjugation degree for the PPy precursor of CPPy-NaOH facilitates formation of micropores during carbonization. CPPy-NaOH exhibits much higher specific capacitance than CPPy-HCl. Furthermore, CPPy-NaOH gives much larger surface efficiency and higher capacitance retention ratios as compared to a commercial activated carbon for supercapacitors.