Latest ArticlesSynthetic conditions and ligands are the key structural defining factors of metal–organic frameworks (MOFs). Therefore, reasonable optimization of these aspects is considered to be an effective means for designing materials with novel structures and target functions. Herein, two novel Co(Ⅱ)-based MOFs, namely [Co(HL)(dibp)]n (HL-8) and {[Co2(L)(OH)(dibp)]·DMA}n (HL-9) (H3L = 2′, 6′-dimethyl-[1,1′-biphenyl]-3,4′,5-tricarboxylic acid; dibp = 4,4′-di(1H-imidazol-1-yl)-1,1′-biphenyl]), have been hydrothermally synthesized and structurally characterized. HL-8 crystallizes in the orthorhombic system (Pna21) with a grid layer structure, while HL-9 crystallizes in the monoclinic P21/n space group assembled through Co4(OH)2 clusters with organic ligands. Remarkably, benefiting from the finite cage-like structure, HL-9 exhibited enhanced performance in carbon dioxide (CO2) adsorption/catalytic transformation and excellent size selectivity during dye molecular adsorption process.
Gel polymer electrolytes (GPEs) are promising alternatives to liquid electrolytes applied in high-energy-density batteries. Here superior SiO2 nanofiber composite gel polymer electrolytes (SNCGPEs) are developed via in-situ ionic ring-opening polymerization of 1,3-dioxolane (DOL) monomers in SiO2 nanofiber membrane (PDOL-SiO2) for lithium metal batteries. The oxygen atoms of PDOL together with Si-O of SiO2 construct a more efficient channel for Li+ migration. Consequently, the lithium ion transference number (tLi+) and ionic conductivity (σ) at 30 ℃ of PDOL-SiO2 are 0.80 and 1.68 × 10−4 S/cm separately. PDOL-SiO2 manifests the electrochemical decomposition potentials of 4.90 V. At 0.5 mA/cm2, Li|PDOL-SiO2|Li cell shows a steady cycling performance for nearly 1400 h. LFP|PDOL-SiO2|Li battery can steadily cycle at 0.5 C with a capacity retention rate of 89% after 200 cycles. While cycling at 2 C, the capacity retention rate can maintain at 78% after 300 cycles. This contribution provides a innovative strategy for accelerating Li+ transportation via designing PDOL molecular chains throughout the SiO2 nanofiber framework, which is crucial for high-energy-density LMBs.
Available online two new Ni8Mo8 bimetallic coordination clusters, [Ni4(TC4A)]2[(Mo5ⅤMo3ⅥO24)(PO4)] (+Solvent) (Ni8PMo8, H4TC4A= p-tert-butylthiacalix[4]arene) and [Ni4(TC4A)]2[(Mo5ⅤMo3ⅥO24)(OH)(CO3)] (+Solvent) (Ni8Mo8), were synthesized by solvothermal method and structurally characterized by single-crystal X-ray diffraction, powder X-ray diffraction, FT-IR spectroscopy, and TGA experiments, respectively. The usage of H3PMo12O40 as source for Ni8PMo8 resulted a sandwich like structure built from two Ni4-thiacalix[4]arene units and a Mo8 polyoxometalate with inner spaces of PO43−. Ni8Mo8 with the similar structure to that of Ni8PMo8 is from H2MoO4 starting reagent with OH− and CO32− anions encapsulated in the center. The two clusters can be directly loaded on carbon paper and utilized as working electrodes which showed distinguishable performances for glucose detection and oxidation. This work provides a better understanding of the structure–property relationships in using substituted polyoxometalates for electrochemical applications and is helpful for building calixarene-based or polyoxometalate-based functional materials.
High entropy oxides (HEOs) have attracted extensive attention of researchers due to their remarkable properties. The electrocatalytic activity of electrocatalysts is closely related to the reactivity of their surface atoms which usually shows a positive correlation. Excellenet stability of HEOs leads to their surface atoms with relative poor reactivity, limiting the applications for electrocatalysis. Therefore, it is significant to activate surface atoms of HEOs. Constructing amorphous structure, introducing oxygen defects and leaching are very effective strategies to improve the reactivity of surface atoms. Herein, to remove chemical inert, low-crystallinity (Fe, Co, Ni, Mn, Zn)3O4 (HEO-Origin) nanosheets with abundant oxygen vacancies was synthesized, showing an excellent catalytic activity with an overpotential of 265 mV at 10 mA/cm2, which outperforms as-synthesized HEO-500℃-air (335 mV). The excellent catalytic performance of HEO-Origin can be attributed to high activity surface atoms, the introduction of oxygen defects efficiently altered electron distribution on the surface of HEO-Origin. Apart from, HEO-Origin also exhibits an outstanding electrochemical stability for oxygen evolution reaction (OER).
The development of efficient and cost-effective electrocatalysts for oxygen evolution reaction (OER) is crucial for the overall water splitting. Herein, we prepared a highly exposed NiFeOx ultra-small nanoclusters supported on boron-doped carbon nonotubes catalyst, which achieves a 10 mA/cm2 anodic current density at a low overpotential of 213 mV and the Tafel slope of 52 mV/dec in 1.0 mol/L KOH, superior to the pristine NiFeOx-CNTs and other state-of-the-art OER catalysts in alkaline media. A combination study (XPS, sXAS and XAFS) verifies that the local atomic structure of Ni and Fe atoms in the nanoclusters are similar to NiO and Fe2O3, respectively, and the B atoms which are doped into the crystal lattice of CNTs leads to the optimization of Ni 3d eg orbitals. Furthermore, in-situ X-ray absorption spectroscopies reveal that the high valence state of Ni atoms are served as the real active sites. This work highlights that the precise control of highly exposed multicomponent nanocluster catalysts paves a new way for designing highly efficient catalysts at the atomic scale.
Based on the reported Fe clusters constructed by using N-tris(hydroxymethyl)methylglycine (H5thmmg), herein, we explored the use of H5thmmg for Ni chemistry. Successfully, an octanuclear Ni cluster, Ni8O(H3thmmg)6·2NO3 (Ni8) was acquired under solvothermal condition. Its metallic core is comprised of two centrosymmetric cubanes Ni4(µ3-O)3(µ6-O) linked by sharing an O2− ion and six H3thmmg2− ligands are attached to the periphery. Interestingly, the 2-mercapto-5-amino-1,3,4-thiadiazole (Hmat) ligand with both N and S donor atoms was introduced into the synthesis of Ni8 cluster, a disparate decanuclear nickel cluster, Ni10O(OH)2(H3thmmg)4(mat)8 (Ni10) is assembled by H3thmmg2− and mat− mixed ligands. The metal core of Ni10 cluster is a pudgy tetrahedron, whose four vertexes are four Ni2+ ions and the remanent six Ni2+ ions are located in the tetrahedral cavity. Four H3thmmg2− ligands are located at the four vertices of the tetrahedron and 8 mat− ligands are all on the six sides of the tetrahedron. The different synthetic conditions contribute to the different configurations. Magnetic studies indicate that both complexes Ni8 and Ni10 display antiferromagnetic interactions.
Stimulus-responsive vesicles have broad applications in a variety of areas. Herein, oxidation-responsive framboidal triblock copolymer vesicles are prepared by photoinitiated RAFT seeded emulsion polymerization of a thioether-functionalized monomer using diblock copolymer vesicles as seeds. The obtained framboidal vesicles can transform into worms or spheres in the presence of reactive oxygen species, which can be further used for controlled release of cargos (e.g., silica nanoparticles).
Achieving efficient degradation of organic pollutants via activation of sulfite is meaningful but challenging. Herein, we have constructed a heterogeneous catalyst system involving Co3O4 and TiO2 nanoparticles to form the p-n heterojunction (Co3O4/TiO2) to degrade acetaminophen (ACE) through photocatalytic activation of sulfite. Specifically, X-ray photoelectron spectroscopy analysis and theoretical calculations provide compelling evidence of electron transfer from Co3O4 to TiO2 at the heterointerface. The interfacial electron redistribution of Co3O4/TiO2 tunes the adsorption energy of HSO3‒/SO32‒ in sulfite activation process for enhanced the catalytic activity. Owing to its unique heterointerface, the degradation efficiency of ACE reached 96.78% within 10 min. The predominant active radicals were identified as •OH, h+, and SOx•− through radical quenching experiments and electron spin resonance capture. Besides, the possible degradation pathway was deduced by monitoring the generated intermediate products. Thereafter, the enhanced roles of well-engineered compositing interface in photocatalytic activation of sulfite for complete degradation of ACE were unveiled that it can improve light absorption ability, facilitate the generation of active species, and optimize reactive pathways. Considering that sulfite is a waste from flue gas desulfurization process, the photocatalytic activation of sulfite system will open up new avenues of beneficial use of air pollutants for the removal of pharmaceutical wastewater.
A novel thiazolothiazole-bridged imidazole derivative (1) was found to exhibit blue fluorescence in gaseous state or in methanol and yellow fluorescence in solid state. The N-alkylation of imidazole subunit(s) in 1 using n-propyl iodide generated unsymmetrically or symmetrically alkylated thiazolothiazole-bridged imidazolium salts with good water solubility and remarkably strong emission in solution. Furthermore, the replacement of iodide counter-anion by triflate or bis(trifluoromethane sulfonyl)imide achieved remarkably strong emission in solid state and in solution as well as good water solubility. The strong fluorescence of dicationic salts with triflate and NTf2– counter-anions in solid state can be ascribed to their twisted and rigid structures induced by interionic C−H···F hydrogen bonding.
During the past few years, the construction of BODIPY-based supramolecular fluorescent metallacages through coordination-driven self-assembly has gained increasing interest due to their unique photophysical properties and applications in catalysis, sensing, and bioimaging. In consideration of the rapid development of this field, it is time to summarize recent developments involving BODIPY-based metallacages. In this review, a comprehensive summary of the construction of BODIPY-based metallacages as well as their photophysical properties and applications will be presented.