Latest ArticlesZinc-ion hybrid super-capacitors are regarded as promising safe energy storage systems. However, the relatively low volumetric energy density has become the main bottlenecks in practical applications of portable electronic devices. In this work, the zinc-ion hybrid super-capacitor with high volumetric energy density and superb cycle stability had been constructed which employing the high-density three-dimensional graphene hydrogel as cathode and Zn foil used as anode in 1 mol/L ZnSO4 electrolyte. Benefiting from the abundant ion transport paths and the abundant active sites for graphene hydrogel with high density and porous structure, the zinc-ion hybrid super-capacitor exhibited an extremely high volumetric energy density of 118.42 Wh/L and a superb power density of 24.00 kW/L, as well as an excellent long cycle life (80% retention after 30,000 cycles at 10 A/g), which was superior to the volumetric energy density of the reported zinc-ion hybrid super-capacitors. This device, based on the fast ion adsorption/desorption on the capacitor-type graphene cathode and reversible Zn2+ plating/stripping on the battery-type Zn anode, which will inspire the development of zinc-ion hybrid super-capacitor in miniaturized devices.
By taking the functional advantages of both pyrazolate and carboxylate ligands, a unique dual-functional pyrazolate-carboxylate ligand acid, 4-(3,6-di(pyrazol-4-yl)-9-carbazol-9-yl)benzoic acid (H3PCBA) was designed and synthesized. Using it, a new Co(II)-based metal-organic framework (MOF), Co3(PCBA)2(H2O)2 (BUT-75) has been constructed. It revealed a (3,6)-connected net based on the 6-connected linear trinuclear metal node, and showed good chemical stability in a wide pH range from 3 to 12 at room temperature, as well as in boiling water. Due to the presence of rich exposed Co(II) sites in pores, BUT-75 presented high selective CO2 adsorption capacity over N2 at 298 K. Simultaneously, it demonstrated fine catalytic performance for the cycloaddition of CO2 with epoxides into cyclic carbonates under ambient conditions. This work has not only enriched the MOF community through integrating diverse functionalities into one ligand but also contributed a versatile platform for CO2 fixation, thereby pushing MOF chemistry forward by stability enhancement and application expansion.
With the development of single-molecule detection and super-resolution fluorescence imaging, rhodamine dyes gain new life. Through the modification of the N-substituents and the replacement of the oxygen atom in xanthene, the wavelength and brightness can be effectively changed. However, the spectra of rhodamine, especially due to the balance between ring-closed non-fluorescent lactone and ring-opened fluorescent zwitterion/cation, are sensitive to interference from various environmental factors. In this way, the spectral data of various rhodamines reported by different research groups under different test conditions lacked comparability, sometimes even lacked accuracy. In order to meet the requirements for the accuracy and uniformity of spectral data in the research of single molecule imaging and dye structure-fluorescence relationship study, we have tested the spectra of fifteen rhodamine dyes that cover the visible and near-infrared regions under exactly the same conditions. By studying the dependence of the spectra on dye concentrations, it was confirmed that 1 μmol/L was ideal for detection less from the interference of dye molecule aggregation. We provide comprehensive and reliable spectral data of these fifteen dyes, which are expected to be used as references for future research. And the direct comparison of different rhodamine spectra would help to understand the structure-fluorescence relationship of rhodamines.
In this work, titanium-capped cobalt clathrochelates have been applied as secondary building units (SBUs) for the construction of supramolecular rings. Two heterometallic wheel-like [Ti6Co12] complexes based on cobalt clathrochelates, [C6H15N4]2[TiCo2(μ2-Oipr)(Oipr)2(Dmg)3]6 (2, Dmg=dimethylglyoxime) and H6[TiCo2(μ2-Oipr)(Oipr)2(Dmg)3]6 (3), have been successfully synthesized and characterized. The supramolecular stacking modes of these wheels are largely dependent on the applied synthetic conditions, which further impact their gas adsorption properties.
Reliable technologies for CO2 capture and conversion (C3) are of vital importance for the establishment of a sustainable society. Metal-organic framework (MOF) composites have shown their compelling potentials for C3 due to the plentiful reticular chemistry of MOF structures and the synergistic catalysis between MOFs and the functional guests. This review focuses on the syntheses and catalytic applications towards C3 of MOF composites, which is divided into three sections. The first section gives a brief introduction about synthetic strategies of MOF composites. The second section discusses the recent progress of MOF composites in C3, including CO2 chemical fixation, hydrogenation, photoreduction, electroreduction and photoelectroreduction. The third section summarizes the challenges and future prospects of MOF composites for C3. We hope that this review cannot only provide an inspiration for the rational design of MOF composites for C3, but also stimulate more and more research works in this emerging area.
The N-heterocyclic carbene (NHC)-catalyzed reactions involving two-electron reaction pathway have been well-established. However, the development of NHC-catalyzed radical reactions is still in its infancy in terms of reaction types and enantioselectivity. In the past decade, several elegant NHC-catalyzed radical reactions have been developed, including NHC-catalyzed oxidation of aldehydes to esters, reductive coupling reactions using Breslow intermediate as SET reductant and NHC-catalyzed reactions via radical homoenolates, dienoaltes and trienolates. This review summarizes the recent advances in NHC-catalyzed reactions involving radical intermediates.
A novel kind of fully bio-based PSAs were obtained through the curing reaction between two components derived from the plant oils: carboxyl-terminated polyricinoleate (PRA) from the castor oil and epoxidized soybean oil (ESO). The gel content, glass transition temperature (Tg), rheological behavior, tensile strength, creep resistance and 180° peel strength of the PSAs were feasibly tailored by adjusting the component ratio of ESO to PRA. At low cross-linking level, the PSAs behaved like a viscous liquid and did not possess enough cohesiveness to sustain the mechanical stress during peeling. The PSAs cross-linked at or near the optimal stoichiometric conditions displayed an adhesive (interfacial) failure between the substrate and the adhesive layer, which were associated with the lowest adhesion levels. The PSAs with the dosage amount of ESO ranging from 10~20 wt% were tacky and flexible, which exhibited 180° peel strength ranging from 0.4~2.3 N/cm; and could be easily removed without any residues on the adherend. The process for the preparation of the fully bio-based PSAs was environmentally friendly without using any organic solvent or other toxic chemical, herein showing the great potential as sustainable materials.
Numerous scientists are in the pursuit of energy storage materials with high energy and high power density by assembly of electrochemically active materials into conductive scaffolds, owing to the emerging need for next-generation energy storage devices. In this architectures, the active materials bonded to the conductive scaffold can provide a robust and free-standing structure, which is crucial to the fabrication of materials with high gravimetric capacity. Thus, hierarchical copper-cobalt-nickel ternary oxide (CuCoNi-oxide) nanowire arrays grown from copper foam were successfully fabricated as free-standing anode materials for lithium ion batteries (LIBs). CuCoNi-oxide nanowire arrays could provide more active sites owing to the hyperbranched structure, leading to a better specific capacity of 1191 mAh/g, cycle performance of 73% retention in comparison to CuO nanowire structure, which exhibited a specific capacity of 1029 mAh/g and capacity retention of 43%, respectively.
With increasing demand for renewable energy, graphene-like BC3 monolayer as high performance electrode materials for lithium and sodium batteries are drawing more attention recently. However, its structural stability, potassium storage properties and strain effect on adsorptionproperties of alkali metal ions have not been reported yet. In this work, phonon spectra, AIMD simulations and elastic constants of graphene-like BC3 monolayer are investigated. Our results show that graphene-like BC3 monolayer possesses excellent structural stability and the maximum theoretical potassium storage capacity can reach up to 1653 mAh/g with the corresponding open circuit voltages 0.66 V. Due to potassium atom can be effectively adsorbed at the most energetically favorable h-CC site with obvious charge transfer, making adsorbed graphene-like BC3 monolayer change from semiconductor to metal which is really good for electrode utilization. Moreover, the migrations potassium atom on the graphene-like BC3 monolayer is rather fast with the diffusion barriers as low as 0.12 eV, comparing lithium atom with a relatively large diffusion barrier of 0.46 eV. Additionally, the tensile strains applied on the graphene-like BC3 monolayer have marginal effect on the adsorption and diffusion performances of lithium, sodium and potassium atoms.
Imitating the signal transduction and transmembrane transport controlled by biological channels in the cell membrane, artificial nanochannels with a similar capability of sensing and transport are constructed as bionic nanochannels. To accomplish selective sensing and transport of biological analyte (as "guest"), the bionic nanochannels are modified with the artificial receptor (as "host"). Based on selective recognition between host and guest, bionic nanochannels translate the stimulus of the guest to electrochemical signal as sensors, and further regulate the transmission of guest as transporters. However, throughout all kinds of guests, the selective sensing and transport of ions and chiral molecules is a challenging problem. And throughout all hosts of ions and chiral molecules, the macrocyclic hosts with multisite of recognition show better selectivity, such as crown ethers, cyclodextrins, calixarenes, and pillararenes. In this article, we highlight recent advances in the macrocyclic host-based nanochannels for the selective sensing and transport of ionic and chiral guests, summarize the similarities and differences of different kinds of macrocyclic host-based nanochannels, and expect the research direction and application prospect.
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