Latest ArticlesMetal organic framework (MOF) has been confirmed as the promising precursor to develop the conversion-typed anode materials of sodium-ion batteries (SIBs) because of the tunable structure design and simple functional modification. Here, we prepare the ultrasmall Ni3S2 nanocrystals embedded into N-doped porous carbon nanoparticles using the scalable Ni-MOF as precursor (denoted as Ni3S2@NPC). The ultrasmall size of Ni3S2 can work for accelerated electron/ion transfer to facilitate the electrochemical reaction kinetics. Moreover, the robust conductivity network originated from N-doped porous carbon nanoparticles can not only improve the electron conductivity, but also enhance the electrode integrity and stability of the electrode/electrolyte interface. In addition, the N heteroatoms provide extra Na storage sites. Accordingly, the electrode delivers the obviously competitive capacities and high-power output with respect to the currently reported Ni3S2/C composites. This study provides a scalable and universal strategy to develop the advanced transition metal sulfides for practically feasible SIBs.
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.
We design a ratiometric fluorescent sensing platform for bleomycin (BLM) by using proximity-dependent DNA-templated silver nanoclusters (DNA-AgNCs) probe. This ratiometric sensing system is constructed with DNA-AgNCs as single fluorophore. The proposed strategy is based on the two following facts: (1) a covert DNA can approach and transform the DNA-AgNCs with green emission (G-DNA-AgNCs) into red emission through hybridization reaction. (2) The specific cleavage of the convert DNA by BLM in the presence of Fe(II) inhibits the discoloration of G-DNA-AgNCs. Thus, benefiting from the specific recognition of BLM and unique properties of G-DNA-AgNCs, a highly-sensitive ratiometric sensor for BLM has been successfully developed. The detection limit is as low as 30 pmol/L. This label-free fluorescence probe possesses advantages of convenient synthetic process and low cost. Moreover, this ratiometric method has been applied to the detection of BLM in human serum samples, illustrating a promising tool for analysis of BLM in cancer therapy.
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.
Porous structure and heteroatom doping are two key parameters for significantly boosting the capacitive performance of graphene-based materials. Herein, we report a facile approach to prepare one-dimensional (1D) nitrogen-doped holey graphene nanoscrolls (NHGNSs) through cold quenching treatment of two-dimensional graphene oxide sheets, followed by thermal annealing in the successive atmosphere of NH3 and air. Benefiting from the synergy of the unique 1D tubular morphology, abundant nanoholes and nitrogen doping, the NHGNSs exhibit a high specific capacitance of 126 F/g at 1 A/g in ionic liquid electrolyte and excellent rate capability with 81% of the capacitance retained at 20 A/g. Furthermore, the fabricated symmetric supercapacitors based on NHGNSs achieve both high energy density of 53.5 Wh/kg at 875 W/kg and high power density of 17.5 kW/kg at 43.4 Wh/kg. The simple synthetic process and superior electrochemical performance suggest the great potential of NHGNSs for supercapacitor application.
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.
Zinc-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 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.
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.
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