Benzoate Acid-Dependent Lattice Dimension of Co-MOFs and MOF-Derived CoS₂@CNTs with Tunable Pore Diameters for Supercapacitors

Abstract

Herein three novel cobalt metal-organic frameworks (Co-MOFs) with similar ingredients, [Co(bib)(o-bdc)] (1), [Co(bib)(m-bdc)] (2), and {[Co(bib)(p-bdc)(HO)](HO)} (3), have been synthesized from the reaction of cobalt nitrate with 1,4-bis(imidazol-1-yl)benzene (bib) and structure-related aromatic acids (1,2-benzenedicarboxylic acid = o-bdc, 1,3-benzenedicarboxylic acid = m-bdc, and 1,4-benzenedicarboxylic acid = p-bdc) by the solvothermal method. It is aimed to perform systematic research on the relationship among the conformation of benzoate acid, lattice dimension of Co-MOF, and pore diameter of MOF-derived carbon composite. Through the precursor strategy, Co-MOFs 1-3 have been utilized to synthesize porous cobalt@carbon nanotube composites (Co@CNTs). After the in situ gas-sulfurization, secondary composites CoS@CNTs were successfully obtained, which kept similar morphologies of corresponding Co@CNTs without destroying previous highly dispersed structures. Co-MOFs and two series of composites (Co@CNTs and CoS@CNTs) have been well characterized. Topology and Brunauer-Emmett-Teller analyses elucidate that the bdc ion could control the pore diameters of MOF-derived carbon composites by adjusting the lattice dimension of Co-MOFs. The systematic studies on electrochemical properties demonstrate that (p)-CoS@CNT possesses hierarchical morphology, moderate specific surface area, proper pore diameter distribution, and high graphitization, which lead to remarkable specific capacitances (839 F g at 5 mV s and 825 F g at 0.5 A g) in 2 M potassium hydroxide solution. In addition, the (p)-CoS@CNT electrode exhibits good electrochemical stability and still retains 82.9% of initial specific capacitance at the current density of 1 A g after 5000 cycles.

Covalent Organic Frameworks: A New Class of Porous Organic Frameworks for Supercapacitor Electrodes

“…To be honest, the properties of COFs electrodes in specific capacitance are poorer compared with its analogue MOFs. [101][102][103][104] It can be attributed to the poor conductivity and the slow charge transfer rate of itself on account of the structures formed with organic units. However, the outstanding cycling stability and long cycling life can't be neglected.…”

Frontispiece: Controllable Syntheses of MOF‐Derived Materials

“…b) The schematic illustration of fabricationo fCoS2@CNTsa nd their supercapacitorp erformance. Reproduced with permission from reference [51].C opyright 2017, American Chemical Society.…”

“…It is speculated that inherent crystal structureso fM OFs possess predominant influences on MOF-derived materials, which have been rarely investigated.I no ur recent work, we intensively performed as tudy on the relationship among the conformationo fb enzoate acid, lattice dimension of Co-MOF,a nd pore diameter of MOF-derived Co@CNT composite (Figure 9a). [51] Three structure-related benzenedicarboxylica cids, obdc, m-bdc and p-bdc (1,2-benzenedicarboxylic acid = o-bdc, 1,3-benzenedicarboxylica cid = m-bdc,a nd 1,4-benzenedicarboxylic acid = p-bdc), weres elected as the primaryl igand to construct as eries of Co-MOFs 1-3.O na ccount of the unaltered connecting mode of Co II ion and bib ligand,structures of Co-MOFs are modulated by the extensiono fb enzoate acid. The conformational disparityo fH 2 bdc provides an opportunity to investigate how to controlo ver the lattice dimension of MOFs, which is closely related to the pore diameter of MOF-derived materials.…”

A Porous Carbon Polyhedron/Carbon Nanotube Based Hybrid Material as Multifunctional Sulfur Host for High‐Performance Lithium‐Sulfur Batteries

“…MOFs have attracted growing research interest on account of their abundant diversity in structure and composition by selecting different metal centers and complexing ligands . MOFs‐derived advanced nanomaterials with multiple architecture and tailored chemical composition are widely utilized in electrochemical energy storage and conversion fields, such as electrocatalysis, Li/Na‐ion batteries and supercapacitors . Specially, typical zeolitic imidazolate framework‐67 (ZIF‐67) has the extremely inexpensive and facile synthetic route and the superiority of abundant and controllable pore structure.…”

“…[24] MOFsderived advanced nanomaterials with multiple architecture and tailored chemical composition are widely utilized in electrochemical energy storage and conversion fields, such as electrocatalysis, Li/Na-ion batteries and supercapacitors. [25][26][27][28] Specially, typical zeolitic imidazolate framework-67 (ZIF-67) has the extremely inexpensive and facile synthetic route and the superiority of abundant and controllable pore structure. Furthermore, ZIF-67 possesses the high content of nitrogen and cobalt element that can be act as an appropriate precursor to synthesize the conductive porous Co-embedded N-doped carbon nanomaterial.…”