Yanrui Hao,Hao Guo,Mingyue Wang,Liping Peng,Henglong Ren,Wu Yang
In this article, MOF-derived (NiCo)Se 2 -x-CeO 2 sphere-rod structure composite with mixed ligands (BPDC: biphenyl-4, 4′-dicarboxylic acid, PTA : terephthalic acid) is constructed via a two-step solvothermal technique. The carboxyl functional groups of BPDC act as nucleation modulation to inhibit transverse growth of MOF by enhancing steric hindrance , and two symmetric carboxyl groups and unsaturated metal nodes of adjacent layers generate the coordination, thus forming ordered nanostructures with relatively large aspect ratio. The structure produces larger pores to balance the opposite and different rate of diffusion for metal and nonmetallic ions in hydrothermal selenization. The construction of heterostructure by combining highly reactive (NiCo)Se 2 with low reactive CeO 2 improves diffusion kinetics. As-prepared (NiCo)Se 2 –3:7-CeO 2 derived from MOF-3:7-CeO 2 of largest aspect ratio generates large mesopore to achieve strong penetration of electrolyte ions and exhibits enhanced performance through synergistic interaction between all components on heterointerface. After testing, the (NiCo)Se 2 –3:7-CeO 2 (PTA:BPDC = 3:7) electrode shows superior specific capacitance of 2715 F g −1 (1222 mAh g −1 ) at 1 A g −1 . The assembled (NiCo)Se 2 –3:7-CeO 2 //AC HSC (hybrid supercapacitor) delivers energy density of 45.9 Wh kg −1 at power density of 747 W kg −1 .
Hong Jia,Xinyu Zhu,Tingting Song,Jinping Pan,Feng Peng,Longhua Li,Yu Liu
Exploring novel structures consisting of multiple highly active components is a crucial challenge for supercapacitor applications. Using an in-situ self-templated method, we demonstrate the controlled fabrication of a fibrous hierarchical nanocomposite made of carbon microfibers covered with a layer of metal–organic framework (MOF) derived from nickel-cobalt layered double-hydroxide (NiCo-LDH) nanosheets decorated with (NiCo)Se 2 nanoparticles . The (NiCo)Se 2 nanoparticles attached tightly onto the surface of the two-dimensional NiCo-LDH, both of which were generated by the decomposition of the NiCo-based MOF, and exhibited multiple active sites that contributed to improved electrical conductivity, high capacity, and structural stability. Density functional theory calculations revealed that the density of states near the Fermi level was significantly enhanced, favoured OH – adsorption, and promoted the kinetics of the electrochemical reaction. Benefiting from the intrinsic synergetic contributions from the hierarchical nanoscale structure, the electrode made from the nanocomposite delivered an impressive capacity of 1394.2 F g −1 (702.7 C g −1 ) at 1 A g −1 . Furthermore, a hybrid supercapacitor based on the developed nanocomposite demonstrated an energy density of 50.6 W h kg −1 and a power density of 800 W kg −1 with high cyclic stability. Our results suggest that the hierarchical nanocomposite can be a powerful electrode for advanced next-generation supercapacitors.
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