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Nitrogen and sulfur co-doped carbons derived from chromium carbide (NSCDC) are successfully synthesized by chemical extraction of chromium atom from chromium carbide and followed by a facile hydrothermal treatment using thiourea as nitrogen and sulfur sources. The physicochemical and electrochemical properties of the as-prepared materials are characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), nitrogen adsorption/desorption isotherm, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Fourier infrared spectroscopy (FTIR), cyclic voltammetry (CV), galvanostatic charge/discharge tests (GCD), electrochemical impedance spectroscopy (EIS) and cycle life measurements. The results demonstrate that nitrogen and sulfur species are successfully incorporated into carbon derived from chromium carbide (CDC), and the obtained NSCDC can still maintain interconnected mesoporous carbon network which is favorable for rapid transport of electrolyte ions. Besides, NSCDC exhibits the enhanced wettability, improved conductivity and excellent supercapacitive performance generated from the incorporation of nitrogen and sulfur. The maximum specific capacitance of 281.2 F g-1 at 1 mV s-1 can be achieved for the NSCDC-4. Moreover, the NSCDC-4 supercapacitor possesses excellent cyclic stability with high capacitance retention of 95% after 6000 consecutive cycles. These exciting results reveal that NSCDC is a kind of promising electrode material for the high performance supercapacitors. [ABSTRACT FROM AUTHOR]

A novel metal-organic-frameworks-derived activated mesoporous carbon polyhedron/Sulfur composite (AMCP-950/S) is successfully designed and synthesized. The composition analysis and structure characteristics of samples are conducted by thermogravimetric analyses (TGA), X-ray powder diffraction (XRD), field-emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM). The electrochemical performances of samples are examined by cyclic voltammetric (CV), charge/discharge and electrochemical impedance spectroscopy (EIS) measurements. The effects of the carbonization temperatures on the physicochemical and electrochemical performances of the resultant mesoporous carbon polyhedron are carefully studied. The results show that the activated mesoporous carbon polyhedron (AMCP-950), which is prepared by the MOF-5 (Zn4O(BDC)3) carbonized at the optimized temperature (950°C) and then KOH activation, has uniform sponge-like morphology, abundant mesoporous structure and huge large specific surface areas of 2211.1 m ²/g. Besides, AMCP-950/S composite shows the high sulfur content of 79.0 wt%, the excellent electrochemical performance with the high initial capacity of 1274.0 mAh/g (based on the weight of C/S active substance) and over 81.7% capacity retention after 50 cycles at a discharge rate of 0.2 C (1 C = 1675 mAh/g) as well as excellent coulombic efficiency. [ABSTRACT FROM AUTHOR]