Porous carbon prepared by zeolitic imidazolate framework ( ZIF‐7‐III ) as the precursor for supercapacitor applications in different electrolytes

Abstract

ZIF-7-III and its nitrogen-doped porous carbon (NPC) structures were synthesized for the first time by direct carbonization and fused with KOH in an argon atmosphere. The morphology and structural characterization of NPC materials were performed by scanning electron microscopy (SEM), Raman, Fourier transform infrared (FT-IR), and X-ray diffraction (XRD) analysis, and their supercapacitive properties were examined as a device form for the first time. The characteristic peak at 2θ = 9.1° in the XRD pattern indicates pure ZIF-7-III phase obtained, and impurity was not observed in the phase of ZIF-7-III. Two broad peaks at nearly 25° and 44° might belong to graphite and its diffractions for the NPC structures. The FT-IR analysis of ZIF-7-III and NPC materials matches well with the reported literature. Raman spectra of the activated NPC material show two prominent peaks located around 1357 and 1592 cm−1. A nonporous dense phase with a 2D stacked-layered structure was detected on the structure of ZIF-7-III. The morphology of activated NPC material turns into the 2D structure to the 3D dodecahedron morphology with an increase in the specific surface area. The cyclic voltammetry and galvanostatic cycling measurements of NPC structures were investigated on the device system in different electrolytes such as KOH, NaOH, LiOH, and Na2SO4. The electrochemical performance of NPC compounds was presented comparatively in a device, and the KOH-activated NPC material showed a higher specific surface area (709.7 m2/g) and higher capacitance value (104 Fg−1 at 0.4 Ag−1 and 118 Fg−1 for 5 mV/s) with low capacitive fade after 4000 charge/discharge cycles among others.