Determination of Coordination Configuration of Rare Earth Ions with Aminoacids in Solutions with Cooperative Vibronic Spectroscopy

The use of cooperative vibronic spectroscopy to measure coordination numbers of the ligands surrounding rare earth ions in solutions was proposed and demonstrated. It is shown that the time-resolved cooperative vibronic spectroscopy is a very useful technique for the determination of the ligand type and ligand number for different coordination groups. Coordination configuration of arginine with Tb3+ in solutions with different pH values was studied. It demonstrates that the carboxy1 of arginine can replace H2O to coordinate with Tb3+ and the coordination number of carboxyl increases with the increase of pH value of the solutions.

Metal-organic frameworks based single-atom catalysts for advanced fuel cells and rechargeable batteries

The next-generation energy storage systems such as fuel cells,metal-air batteries,and alkali metal(Li,Na)-chalcogen(S,Se)batteries have received increasing attention owing to their high energy density and low cost.However,one of the main obstacles of these systems is the poor reaction kinetics in the involved chemical reactions.Therefore,it is essential to incorporate suitable and efficient catalysts into the cell.These years,single-atom catalysts(SACs)are emerging as a frontier in catalysis due to their maximum atom efficiency and unique reaction selectivity.For SACs fabrication,metal-organic frameworks(MOFs)have been confirmed as promising templates or precursors due to their high metal loadings,structural adjustability,porosity,and tailorable catalytic site.In this review,we summarize effective strategies for fabricating SACs by MOFs with corresponding advanced characterization techniques and illustrate the key role of MOFs-based SACs in these batteries by explaining their reaction mechanisms and challenges.Finally,current applications,prospects,and opportunities for MOFs-based SACs in energy storage systems are discussed.

Strain and interfacial engineering to accelerate hydrogen evolution reaction of two-dimensional phosphorus carbide

Hydrogen,regarded as a promising energy carrier to alleviate the current energy crisis,can be generated from hydrogen evolution reaction(HER),whereas its efficiency is impeded by the activity of catalysts.Herein,effective strategies,such as strain and interfacial engineering,are imposed to tune the catalysis performance of novel two-dimensional(2D)phosphorus carbide(PC)layers using first-principle calculations.The findings show that P site in pristine monolayer PC(ML-PC)exhibits higher HER performance than C site.Intriguingly,constructing bilayer PC sheet(BL-PC)can change the coordinate configuration of P atom to form 3-coordination-P atom(3-co-P)and 4-coordination-P atom(4-co-P),and the original activity of 3-co-P site is higher than the 4-co-P site.When an external compressive strain is applied,the activity of the 4-co-P site is enhanced whereas the external strain can barely affect that of 3-co-P site.Interestingly,the graphene substrate enhances the overall activity of the BL-PC because the graphene substrate optimizes the?GH*value of 4-co-P site,although it can barely affect the HER activity of 3-co-P site and ML-PC.The desirable properties render 2 D PC-based material promising candidates for HER catalysts and shed light on the wide utilization in electrocatalysis.

Radial magnetic field in magnetic confinement device

The intrinsic radial magnetic field（B r） in a tokamak is explored by the solution of the Grad–Shafranov equation in axisymmetric configurations through an expansion of the four terms of the magnetic surfaces. It can be inferred from the simulation results that at the core of the device, the tokamak should possess a three-dimensional magnetic field configuration, which could be reduced to a two-dimensional one when the radial position is greater than 0.6a. The radial magnetic field and the amzimuthal magnetic field have the same order of magnitude at the core of the device. These results can offer a reference for the analysis of the plasma instability, the property of the core plasma, and the magnetic field measurement.

Insights into structural and spectroscopic characterization of Sm^(3+)doped orange rich red emitting CsMgPO_(4)phosphors

In the present study,Sm^(3+)activated inorganic orthophosphate CsMgPO_(4)(CSMP)phosphors were prepared by adopting a solid-state reaction method.The structural phase purity and morphological features were studied by X-ray powder diffraction(XRD)and scanning electron microscopy(SEM),respectively.The molecular structure and vibrational modes were substantiated with the Fourier transform infrared spectroscopy(FTIR)and Raman spectroscopy characterization.The optical bandgap of the host and Sm^(3+)doped phosphors was deduced from the diffused reflectance(DR)spectra with a typical value of 5.72 eV and a small variation is observed with increasing concentrations.A systematic study of photoluminescence(PL)properties of Sm^(3+)doped CSMP phosphors was carried out.From the room temperature excitation and emission spectra,it is found that the phosphor emits in the orange rich red light under the suitable excitation of 402 nm in the UV region and concentration quenching occurs at x=0.02 doping level.The emission peaks observed at around 562,598 and 644 nm confirm the characteristic Sm^(3+)4 f-4 f transitions.The temperature-dependent photoluminescence(TD-PL)of the x=0.02(optimum doping)is recorded from 30 to 210℃,showing good thermal stability even at 150℃.The thermal quenching mechanisms are discussed based on the configuration coordinate model of excitation and emission.The prepared phosphors are found to exhibit near thermal stability compared to the commercially available red phosphors.PL decay time and quantum efficiency were measured.The colour coordinates are found to lie in the orangish-red region of the colour space.Thus the prepared phosphors CSMP:x Sm^(3+)can be useful as a red component in designing UV excitable chip-based phosphor-converted white LED applications.