A new COF linked by an ether linkage (-O-): synthesis, characterization and application in supercapacitance

A new COF (NWNU-COF-4) linked by an aryl ether bond (Ar-O-Ar) was synthesized by the condensation reaction of 2,4,6-trihydroxypyrimidine and trinitrophenol under simple and easy reaction conditions. Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), N-2 adsorption-desorption, thermogravimetric analysis (TGA), powder X-ray diffraction (XRD) and scanning electron microscopy (SEM) were utilized to characterize the product. The BET specific surface area of NWNU-COF-4 was 21.33 m(2) g(-1), and its pore size was about 1.351 nm. Additionally, this method of preparation was simple and cheap. The electrochemical measurements showed that the synthesized NWNU-COF-4 had excellent pseudocapacitive performance with maximum specific capacitance of 133.44 F g(-1) at 0.3 A g(-1) in 6 mol L-1 KOH electrolyte. When the current density increased by 10 times (3.0 A g(-1)), the specific capacitance was 114.12 F g(-1), and the retention rate was 82%. After 10 000 GCD cycles, the capacitance still kept 94% of its initial capacitance.