In-situ structural evolution analysis of Zr-doped Na_(3)V_(2)(PO_(4))_(2)F_(3) coated by N-doped carbon layer as high-performance cathode for sodium-ion batteries

With great superiorities in energy density,rate capability and structural stability,Na_(3)V_(2)(PO_(4))_(2) F_(3)(NVPF)has attracted much attentions as cathode of sodium ion battery(SIB),but it also faces challenges on its poor intrinsic electronic conductivity and the controversial de/sodiation mechanism.Herein,a series of Zr-doped NVPF coated by N-doped carbon layer(~5 nm in thickness,homogenously)materials are fabricated by a sol-gel method,and the optimized heteroatom-doping amounts of Zr and N doping improve intrinsic properties on enlarging lattice distance and enhancing electronic conductivity,respectively.Specifically,among all samples of Na_(3) V_(2-x)Zr_(x)(PO_(4))_(2) F_(3)/NC(NVPF-Zr-x/NC,x=0,0.01,0.02,0.05,and 0.1),the optimized electrode of NVPF-Zr-0.02/NC delivers high reversible capacities(119.2 mAh g^(-1) at0.5 C),superior rate capability(98.1 mA h g^(-1) at 20 C)and excellent cycling performance.The structural evolution of NVPF-Zr-0.02/NC electrode,in-situ monitored by X-ray diffractometer,follows a step-wise Na-extraction/intercalation mechanism with reversible multi-phase changes,not just a solid-solutionreaction one.Full cells of NVPF-Zr-0.02/NC//hard carbon demonstrate high capacity(99.8 mA h g^(-1) at 0.5 C),high out-put voltage(3.5 V)and good cycling stability.This work is favorable to accelerate the development of high-performance cathode materials and explore possible redox reaction mechanisms of SIBs.

Morphology and crystal-plane effects of Zr-doped CeO2 nanocrystals on the epoxidation of styrene with tert-butylhydroperoxide as the oxidant

The morphology effect of Zr-doped CeOwas studied in terms of their activities in the selective oxidation of styrene to styrene oxide using tert-butyl hydroperoxide as the oxidant. In the present work, Zrdoped CeOnanorods exhibited the highest catalytic performance（yield of styrene oxide and TOF value）followed by nanoparticles and nanocubes. For the Zr-doped CeOnanorods, the apparent activation energy is 56.3 k J/mol, which is much lower than the values of catalysts supported on nanoparticles and nanocubes（73.3 and 93.4 k J/mol）. The high resolution transmission electron microscopy results indicated that（100） and（110） crystal planes are predominantly exposed for Zr-doped CeOnanorods while（100）and（111） for nanocubes,（111） for nanoparticles. The remarkably increased catalytic activity of the Zrdoped CeOnanorods is mainly attributed to the higher percentage of Cespecies and more oxygen vacancies, which are associated with their exposed（100） and（110） crystal planes. Furthermore, recycling studies proved that the heterogeneous Zr-doped CeOnanorods did not lose its initial high catalytic activity after five successive recycles.

Theoretical Study of the Structural, Electronic, and Magnetic Properties of Zirconium-doped Aluminum Clusters：AlnZr(n = 1～14)

The geometrical structures, stabilities, electronic and magnetic properties of AlnZr（n = 1~14） clusters have been systematically investigated using density functional theory. It is found that for the optimized clusters the zirconium atom prefers to remain on the surface, and the growth patterns are organized as follows： Zr substituted Aln＋1 clusters or Zr capped Aln clusters as well as Al added Aln-1Zr clusters. All doped clusters exhibit relatively larger average binding energies and magnetic behaviors compared with pure Aln＋1 counterpart. The calculated fragmentation energies and second-order difference of energies exhibit pronounced odd-even alternation behavior as a function of the cluster size when n = 3~13. In all AlnZr clusters, there exits internal hybridization in both Al and Zr atoms and charge transfer from Al to Zr atom, which reflects the strong interactions between the two kinds of atoms. The magnetic property analysis shows that the 4d electrons of Zr atom are the main origin for cluster magnetism.

Degradation of benzene on Zr-doped TiO_2 photocatalysts with a bimodal pore size distribution

Zr-doped TiO2 was prepared from TiOSO4 and ZrOCO3 by a co-precipitation method using NH3H2O as the precipitation agent. The Zr-doped TiO2 was characterized by X-ray diffraction（XRD）, low temperature N2adsorption–desorption measurement, and UV–Vis diffuse reflectance spectroscopy technology. Appropriate amounts of ZrO2 addition can greatly improve the TiO2 microstructure properties and its photocatalytic activities. In addition, polyethylene glycol（PEG） was used as a surfactant for templating the pore structure of samples. A bimodal pore structure can be controlled using PEG6000 and PEG20000 surfactants simultaneously during the preparation. The rate constant of benzene degradation over the Zr-doped TiO2 linearly decreases with the increase of photocatalytic reaction temperature and decreases in a polynomial relation with the benzene concentration.Moreover, it increases approximately linearly with the increase of the illumination intensity or area.

Zr-doped titanium lithium ion sieve and EP-granulated composite:Superb adsorption and recycling performance

Lithium ion sieve(LIS)has attracted great attention due to its high adsorption selectivity towards Li+.Herein,a new type of Zr-doped Ti-LIS(HZrTO)was synthesized by a simple calcination method.The adsorption capacity increased from 56.3 mgg-1(before doping)to 93.2 mgg-1 after doping in LiOH solution(lithium 1.8gL-1).The adsorption isotherm and adsorption kinetics of HZrTO accord with the Langmuir isotherm and the pseudo-second-order kinetic equation,respectively.Batch experiments showed that HZrTO has good stability and selectivity.In addition,HZrTO was granulated via epoxy resin(E-12),and the obtained granular adsorbent showed good adsorption capacity,excellent stability and high selectivity towards Li+.