RESUMEN
In this work, three Cu metal-organic framework samples with tunable rhombic, squama, and trucated bipyramid morphologies have been synthesized at 0, 25, and 60 °C, respectively, and further employed as precursors to initially prepare Cu@C composites by the calcination-thermolysis procedure. Then Cu@C composites have been etched with HCl and subsequently activated with KOH to obtain activated porous carbon (APC-0, -25, and -60). Interestingly, APC-25 presents a loose multilevel morphology of cabbage and possesses the largest specific surface area (1880.4 m2 g-1) and pore volume (0.81 cm3 g-1) among these APC materials. Consequently, APC-25 also exhibits the highest specific capacitance of 196 F g-1 at 0.5 A g-1, and the corresponding symmetric supercapacitor cell (SSC) achieves a remarkable energy density of 11.8 Wh kg-1 at a power density of 350 W kg-1. Furthermore, APC-25 shows excellent cycling stability, and the loss of capacitance is only 7.7% even after 10000 cycles at 1 A g-1. Significantly, five light-emitting diodes can be lit by six SSCs, which proves that APC-25 can be used in energy storage devices.
RESUMEN
In this work, three isomeric benzenedicarboxylates, 1,2-benzenedicarboxylic acid (o-H2bdc), 1,3-benzenedicarboxylic acid (m-H2bdc), and 1,4-benzenedicarboxylic acid (p-H2bdc) have been utilized as the ancillary ligands to perform a systematic study on the structural diversity of mixed-ligand frameworks. The solvothermal reactions of Co(NO3)2 with these aromatic acids and the primary ligand 4,4'-bis(imidazolyl)biphenyl (bibp) afford three novel coordination polymers, {[Co6(bibp)3(o-bdc)6(H2O)](CH3CN)1.5}∞ (1), [Co(bibp)(m-bdc)]∞ (2), and [Co(bibp)(p-bdc)]∞ (3). Owing to the different orientations of the carboxylate groups, the benzenedicarboxylates adopt various bridging modes to connect the Co(II) ions into a series of 1D carboxylateâ©cobalt architectures based on the 1D chain, binuclear and single-ion magnetic units, respectively. These 1D architectures are further decorated by the bibp ligand to afford a 1D belt for , 2D double-bridging (4,4) sheet for 2, and an unusual 3D dmp framework for 3. Significantly in 3, three equivalent frameworks are interlocked with each other to represent an unprecedented three-fold interpenetrating dmp network. The structural diversity indicates that the benzenedicarboxylate plays an essential role in the assembly of mixed-ligand frameworks, and the orientation of the carboxylate group exerts an important influence on the nucleation, dimensionality and also interpenetration. Furthermore, the magnetic properties of 1 and 2 have been studied by fitting the experimental data as possible, and the magneto-structural correlation of 2 has also been well discussed. Importantly, CoO and Co3O4 were obtained from the controllable thermolysis of crystals of 1 via simple calcination treatment under different gas environments. The as-synthesized cobalt oxides display good crystallinity and appear as micro- or nanoparticles, which can be applied as supercapacitor electrodes as demonstrated by their energy storage performance in 2 M KOH electrolyte.
