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.
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.
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.
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.
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.
A novel water-soluble red-emissive AIE fluorescence probe for cysteine (Cys) in situ was prepared and the performance of selectivity and sensitivity has been carefully investigated in this study. The probe was established on the electrostatic interaction of sulfonate functionalized tetraphenylethene (TPE) and polycation generated by the reaction between a polymer bearing dinitrobenzenesulfonate groups and Cys. From the experimental results, it was easy to distinguish Cys from glutathione (GSH) and homocysteine (Hcy) with a detection limit of 73 nmol/L. The assay system also possessed strong anti-interference ability against multitudinous amino acids. The Stokes shift was 142 nm and the emission ranged from 550 nm to 850 nm. In addition, double responses in fluorescence and ultraviolet-visible spectra also make the red-emissive assay ideal for sensitive detection and quantification of Cys for most purposes, especially in-situ monitoring of Cys in aqueous medium.
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.
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.
The nano-Si/graphite nanocomposites are the promising anodes candidates for high-energy lithium-ion batteries because of their high theoretical capacities and low volume variations. However, the nano-Si has a severe tendency to separate from the graphite substrate due to the inherently weak bonding between them, thus leading to the deteriorated cycling performance and low Coulombic efficiency. Herein, we design a robust nano-Si/graphite nanocomposite structure with strong interfacial adhesion caused by the Si—Ti and Ti—C covalent bonds. The abundant Si—Ti and Ti—C bonds formed between nano-Si and graphite greatly enhance the interfacial adhesion force, resulting in the highly stabilized and integrated electrode structure during battery cycling. Consequently, the as-obtained nano-Si/graphite anodes deliver a high capacity retention of 90.0% after 420 cycles at 0.5 C with an average Coulombic efficiency of 99.5%; moreover, a high initial Coulombic efficiency of 90.2% is achieved. Significantly, this work provides a novel strategy to address the poor interfacial adhesion between nano-Si and graphite, which can be applied to other nano-Si based composites anodes.
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