Progress in doping and crystal deformation for polyanions cathode based lithium-ion batteries

Polyanion-based materials are considered one of the most attractive and promising cathode materials for lithiumion batteries(LIBs)due to their good stability,safety,cost-effectiveness,suitable voltages,and minimal environmental impact.However,these materials suffer from poor rate capability and low-temperature performance owing to limited electronic and ionic conductivity,which restricts their practical applicability.Recent developments,such as coating material particles with carbon or a conductive polymer,crystal deformation through the doping of foreign metal ions,and the production of nanostructured materials,have significantly enhanced the electrochemical performances of these materials.The successful applications of polyanion-based materials,especially in lithium-ion batteries,have been extensively reported.This comprehensive review discusses the current progress in crystal deformation in polyanion-based cathode materials,including phosphates,fluorophosphates,pyrophosphates,borates,silicates,sulfates,fluorosilicates,and oxalates.Therefore,this review provides detailed discussions on their synthesis strategies,electrochemical performance,and the doping of various ions.

Influence of Doping Ions on the Antibacterial Activity of Biomimetic Coating on CoCrMo Alloy

In this study biomimetic fluoridated phosphate doped hydrophilic coatings with various ions on CoCrMo alloy were pre- pared by electrodeposition. Cu and Zn ions were chosen for doping because of their well known antibacterial activity. The struc^xes of the coatings were identified using Fourier-transform Infrared （FTIR） analysis. X-ray Diffraction （XRD） analysis was performed to evaluate crystallite dimensions of the specimen surface. The contact angle was measured in order to establish the hydrophilic/hydrophobic balance and to compute surface energy. All studied samples have a hydrophilic character which is weaken after doping. The time evolution of ions releasing from the coatings was evaluated with an inductively plasma mass spectrometer after immersion in saline phosphate. The hemolytic experiments indicate that except the fluoridated coatings doped with Zn which is slightly hemolytic, all other samples are non hemolytic. The test for antibacterial activity for Staphy- lococcus aureus and Pseudomonas aeruginosa indicated that the fluoridated biomimetic coating doped with various positive ions increases bacterial growth inhibition level significantly. Fluoridated phosphate coating doped with Cu has best antibacterial activity

Prolonging charge-separation states by doping lanthanide-ions into {001}/{101} facets-coexposed TiO_(2) nanosheets for enhancing photocatalytic H_(2) evolution

Ultrathin TiO_(2)nanosheets with coexposed{001}/{101}facets have attracted considerable attention because of their high photocatalytic activity.However,the charge-separated states in the TiO_(2)nanosheets must be extended to further enhance their photocatalytic activity for H_(2)evolution.Herein,we present a successful attempt to selectively dope lanthanide ions into the{101}facets of ultrathin TiO_(2)nanosheets with coexposed{001}/{101}facets through a facile one-step solvothermal method.The lanthanide doping slightly extended the light-harvesting region and markedly improved the charge-separated states of the TiO_(2)nanosheets as evidenced by UV-vis absorption and steady-state/transient photoluminescence spectra.Upon simulated sunlight irradiation,we observed a 4.2-fold enhancement in the photocatalytic H_(2)evolution activity of optimal Yb^(3+)-doped TiO_(2)nanosheets compared to that of their undoped counterparts.Furthermore,when Pt nanoparticles were used as cocatalysts to reduce the H_(2)overpotential in this system,the photocatalytic activity enhancement factor increased to 8.5.By combining these results with those of control experiments,we confirmed that the extended charge-separated states play the main role in the enhancement of the photocatalytic H_(2)evolution activity of lanthanide-doped TiO_(2)nanosheets with coexposed{001}/{101}facets.

Photocatalytic Activity of Nanosized TiO_2 Enhanced by co-doping with Fe^(3+) and Nd^(3+) Ions

In this study, nanosized TiO2 co-doped with Fe3+ and Nd3+ ions was synthesized via a sol-gel method. The metallic ion doped TiO2 was thoroughly characterized with XRD and UV-vis, and the photocatalytic activity was evaluated by degrading methylene blue (MB) solution. The results indicated that TiO2 crystalline size was reduced and phase transformation of anatase to rutile was suppressed as the content of doped Nd3+ ion increased in the co-doped TiO2. The UV-vis spectra of co-doped TiO2 seemed to simply overlay two spectra of single metal doped TiO2, and had significantly increased absorbance in the ranges of 400～500 nm, 565～600 nm and 730～765 nm as compared to pure TiO2. The photocatalytic activity of co-doped TiO2 was obviously enhanced, and raised about 30% compared to that of pure TiO2 as doped Nd3+ content was 0.15% and Fe3+ content was 0.05%, respectively. The enhanced catalytic activity was attributed to a synergistic effect of two doped ions, where doped Fe3+ ion inhibited the recombination of photogenerated electron and hole, and Nd3+ ion brought more surface carboxyl to promote the degradation reaction.

Rare Earth Ion Yb^3+ Doping of Bi2WO6 with Excellent Visible-light Photocatalytic Activity

The rare earth ion Yb^3+ doped Bi2WO6 photocatalysts were synthesized by hydrothermal method.Moreover,XRD,XPS,FESEM,TEM,Ramam,N2 adsorption-desorption isotherm measurements and UV-vis diffusion reflectance spectra were used to characterize the Yb^3+ doped Bi2WO6 photocatalysts.The morphology,specific surface area,and pore volume distribution were greatly affected after Yb3+ ions doping.Photocatalytic performance of Bi2WO6 was effectively enhanced after Yb3+ ions doping,6% Yb^3+ doped Bi2WO6 had the best photocatalytic performance,and 96.2% Rhodamine B was degradated after irradiated 30 min,which was 1.29 times that of the pristine one.The enhanced photocatalytic performance was due to the increased specific surface area,decreased energy band gap and inhibition of photoelectron-hole recombination after Yb3+ ions doping.

Photocatalytic degradation of Rhodamine B under visible light with Nd-doped titanium dioxide films

Microporous titanium dioxide films were prepared by the sol-gel methods on glass substrates, using tetrabutyl titanate as source material. In order to absorb the visible light and increase the photocatalytic activities, different concentrations of neodymium ions (Nd/Ti molar ratio was 0.5%, 0.7%, 0.9%, and 1.1% respectively) were added into the sol. X-ray diffraction (XRD), X-ray photoelectron spectros-copy (XPS), and atom force microscopy (AFM) were applied to characterize the modified films. A kind of typical textile industry pollutant (Rhodamine B) was used to evaluate the photocatalytic activities of the films under visible light. The results showed that the activities of the films were improved by doping Nd ions into the sol.

Relationship between Crystal Structure and Luminescence Properties of (Y_(0.96-x)Ln_xCe_(0.04))_3Al_5O_(12) (Ln=Gd, La, Lu) Phosphors

The doping effects of La^3＋, Gd^3＋ and Lu^3＋ on the crystal structure and luminescence properties of （Yo96-x LnxCe0.04）3Al5O12（Ln = Gd, La, Lu） phosphors were studied. The X-ray diffraction patterns presented that with the inerease of the doping concentrations of La^3＋ and Gd^3＋ ions, the d-value of （Y0.96-xLnxCe0.04）3Al5O12 （Ln = Gd, La） inereased and the larger the doping ion, the stronger the effect would be. The doping amount causing phase transition in （Y0.96-xLnxCe0.04）3Al5O12 decreased with the inerease of the ionic radii of the doping lanthanide ions （La^3＋： 0.106 nm, Gd^3＋： 0. 094 nm, Lu^3＋ ： 0.083 nm）. The bigger doping ion of Gd^3＋ made the emission of （Y0.96-xGdxCe0.04）3Al5O12 move to red spectral region, but the smaller one of Lu^3＋ made it blue.

Characterization of metal doped-titanium dioxide and behaviors on photocatalytic oxidation of nitrogen oxides

A series of nanosized ion-doped TiO2 catalysts with different ion content （between 0.1 at.% and 1.0 at.%） have been prepared by wet impregnation method and investigated with respect to their behavior for UV photocatalytic oxidation of nitric oxide. The catalytic activity was correlated with structural, electronic and surface examinations of the catalysts using X-ray diffraction analysis （XRD）, ultraviolet-visible （UV-Vis） absorption spectroscopy, transmission electron microscopy （TEM）, energy disperse spectrometer （EDS） and high resolution-transmission electron microscopy （HR-TEM） techniques. An enhancement of the photocatalytic activity was observed for Zn2＋ doping catalyst ranged from 0.1 at.% to 1.0 at.% which was attributed to the lengthened lifetime of electrons and holes. The improvement in photocatalytic activity could be also observed with the low doping concentration of Cr^3＋ （0.1 at.%）. However, the doping of Fe^3＋, Mo^6＋, Mn^2＋ and the high doping concentration of Cr^3＋ had no contribution to photocatalytic activity of nitric oxide.

Ribbon-like Cu doped V6O13 as Cathode Material for High-performance Lithium Ion Batteries

Ribbon-like Cu doped V6O（13） was synthesized via a simple solvothermal approach followed by heat treatment in air.As an cathode material for lithium ion battery,the ribbon-like Cu doped V6O（13 ）electrode exhibited good capacity retention with a reversible capacity of over 313 m Ah·g^-1 for up to 50 cycles at 0.1C,as well as a high charge capacity of 306 m Ah·g^-1 at a high current rate of 1 C,in comparison to undoped V6O（13 ）electrode（267 m Ah·g^-1 at 0.1C and 273 m Ah·g^-1 at 1 C）.The high rate capability and better cycleability of the doped electrode can be attributed to the influence of the Cu ions on the mophology and the electronic conductivity of V6O（13） during the lithiation and delithiation process.

Rare earth doped CaCu_3Ti_4O_(12) electronic ceramics for high frequency applications

Ca1-xRxCu3Ti4O12(R=La,Y,Gd;x=0,0.1,0.2,0.3) electronic ceramics were fabricated by conventional solid-state reaction method.The microstructure and dielectric properties as well as impedance behavior were carefully investigated.XRD results showed that the secondary phases with the general formula R2Ti2O7 existed at grain boundaries of rare earth doped ceramics,which inhibited abnormal grain growth.The dielectric constant decreased from 4×105 in pure CaCu3Ti4O12(CCTO) ceramics to 2×103 with rare earth doping....

Theoretic and Experimental Studies on Titania Nanotube Doped with Ag Metal Ions

The electronic state density and energy bands of Ag-doped anatase TiO2 are studied by WIEN2k software package based on DFT. The calculation results show that the band-gap of anatase titania became bigger after doping with Ag metal ions. The band-gap transfers from 2.04 to 2.5 eV, but a new energy band appears among the forbidden band after the Ag atom substitution. The interband width of Ag-TiO2 is 0.17 eV, which is located at –0.07 eV; more excitation and jump routes are opened for the electrons. The lowest excitation energy can achieve 1.2 eV, which may allow the photons with lower energy （at longer wavelength, such as visible light） to be absorbed. Ag ions are implanted into the titania nanotube sample by MEVVA （Metal Vapor Vacuum Arc） implanter. The photo-electrochemical response and photo-degradation experiment of titania nanotube samples implanted with Ag ions are tested under UV and visible light; the results indicated that the performance of implanted titania naotubes is enhanced both under UV and visible light; it is worth mentioning that the photocurrent density can reach 0.145 mA/cm2 under visible light, which is 181 times higher than those of pure TiNT, and the k value of degradation methyl orange can obtain 0.30 h-1, which is 71 times higher than that of pure TiNT. All the experimental results are consistent well with the theoretic ones.

Surface modification and characterization of F-Co doped spinel LiMn_2O_4

Spinel LiCo0.09Mn1.91O3.92F0.08 as cathode material was modified with LiCoO2 by the sol-gel method, and the crystal structure, morphology and electrochemical performance were characterized with XRD, SEM, EDS, AAS and charge-discharge test in this paper. The results show that a good clad coated on parent material can be synthesized by the sol-gel method, and the materials with modification have perfect spinel structure. LiCo0.09Mn1.91O3.92F0.08 materials coated by LiCoO2 improve the stability of crystal structure and decrease the dissolution of Mn into electrolyte. With the LiCoO2 content increasing, the specific capacity and cycle performance of samples are improved. The capacity loss is also suppressed distinctly even at 55 ℃.

Preparation and Properties of Lanthanum Trivalent Ion Doped TiO_2 Nanopowders by Liquid Plasma Spray

The lanthanum trivalent ion doped TiO2 nanopowders were prepared by liquid plasma spray with solution of titanium tetra-tert-butoxide and alcohol as feedstock and La(NO3)3·6H2O as doping component. The photocatalytic activity of samples at different doping concentrations in photocatalytic degradation of methyl orange was discussed. The powders were characterized by Transmission Electron Microscopy (TEM) and X-Ray Diffraction (XRD), and the effect of doped ion on the pattern, phase composition and crystallite sizes were analyzed. The results indicated that lanthanum trivalent ion doped TiO2 nanopowders could be prepared by liquid plasma spray. Lanthanum trivalent ion doping increased the photocatalytic activity of TiO2 greatly, the optimal doping concentration was 0.5%. The doped powders were the mixture of anatase phase and rutile phase. The contents of anatase phase decreased firstly and then increased with an increase in the contents of lanthanum trivalent ion. Doping lanthanum trivalent ion could make the TiO2 nanopowders uniform and reduced its particle size.

Photocatalytic Inhibition of Cyanobacterial Growth Using Silver-doped TiO_2 under UV-C Light

Capacity of the silver-doped TiO2 under UV-C light to restrain cyanobacterial growth was explored with Anabaena sp. PCC 7120 and Microcystis aeruginosa as test species. The survival, chlorophyll bleaching, photosynthetic activity, DNA breakages, antioxidant enzyme activities, lipid peroxidation, and cellular morphologic structure of test cyanobacteria were analyzed. The results indicate that the test cyanobacteria with UV-C photocatalysis by silver-doped TiO2 sufferd from effects of reactive oxygen species, which promote the damage of the cell wall and the peroxidation of cell membranes, and subsequently, aggravate the losses of cell organelle and viability. The results suggest that UV-C photocatalysis by the silver ions doped TiO2 could be a promising method to prevent fast and excessive growth of cyanobacteria in eutrophic water sources.

Effect of Doped Alkali Metal Ions on the SO_(2) Capture Performance of MnO_(2) Desulfurization Materials at Low Temperature

Sulfur dioxide(SO_(2))emissions from diesel exhaust pose a serious threat to the environment and human health.Thus,desulfurization technology and the performance of desulfurization materials must be improved.In this study,MnO_(2) was modified with various alkali metal ions using the impregnation method to enhance its SO_(2) capture performance.The composites were characterized intensively by scanning electron microscopy,energydispersive X-ray spectroscopy,X-ray diffraction spectroscopy,and Brunauer-Emmett-Teller theory.The SO_(2) capture performance of these composites were measured via thermogravimetry,and the effect of doping with alkali metal ions on the SO_(2) capture performance of MnO_(2) was investigated.Results showed that the SO_(2) capture performance of MnO_(2) could be enhanced by doping with alkali metal ions,and the MnO_(2) composite doped with LiOH(2.0 mol/L)had the best SO_(2) capture capacity(124 mgSO_(2)/gMaterial),which was 18%higher than that of pure MnO_(2).Moreover,the type and concentration of alkali metal ions had varying effects on the SO_(2) capture performance of MnO_(2).In our experiment,the SO_(2) capture performance of the MnO_(2) doped with NaOH,LiCl,Na2CO3,K2CO3,and Li2CO3 composites were worse than that of pure MnO_(2).Therefore,the influences of the type and concentration of alkali metal ions to be doped into desulfurization materials must be considered comprehensively.

Regulating Electron-Hole Separation to Promote the Photocatalytic Property of BiOBr_1−xI_x/BiOBr Local Distorted Hierarchical Microspheres

In this work, hierarchical BiOBr1−xIx/BiOBr heterojunction photocatalyst with a microsphere morphology was synthesized by a facile solvothermal process. It demonstrated that the local structure of the photocatalysts was highly distorted due to the substitution of bromide ions by iodine ions. The photocatalytic properties were evaluated by the photodecomposition of aqueous phenol solution under visible-light irradiation. The results indicated that all the composite photocatalysts exhibited high photocatalytic activity. In particularly, the BiOBr1−xIx/BiOBr (x = 0.25) sample exhibited over 92% degradation efficiency of phenol within 150 min, which is 24.6 and 3.08 fold enhancement in the photocatalytic activity over the pure phased BiOBr and BiOI, respectively. Moreover, this excellent photocatalytic property can be expanded to other colorless organic contaminants, verifying the common applicability of BiOBr1−xIx/BiOBr (x = 0.25) as an excellent visible-light photocatalyst for organics decomposition. The significant improvement in the photocatalytic activity can be explained by the high efficiency of charge separation due to the enhancement in the internal electric fields and band match that comes from the local structure distortion. This work provides valuable information for the design of highly active photocatalysts toward the environmental remediation.

White light emission in 0D halide perovskite[(CH_(3))_(3)S]_(2)SnCl_(6)·H_(2)O crystals through variation of doping ns^(2) ions

With the rapid development of white LEDs,the research of new and efficient white light emitting materials has attracted increasing attention.Zero dimensional(0D)organic–inorganic hybrid metal halide perovskites with superior luminescent property are promising candidates for LED application,due to their abundant and tailorable structure.Herein,[(CH_(3))_(3)S]_(2)SnCl_(6)・H_(2)O is synthesized as a host for dopant ions Bi^(3+)and Sb^(3+).The Sb^(3+)doped,or Bi^(3+)/Sb^(3+)co-doped,[(CH_(3))3S]_(2)SnCl_(6)・H_(2)O has a tunable optical emission spectrum by means of varying dopant ratio and excitation wavelength.As a result,we can achieve single-phase materials suitable for emission ranging from cold white light to warm white light.The intrinsic mechanism is examined in this work,to clarify the dopant effect on the optical properties.The high stability of title crystalline material,against water,oxygen and heat,makes it promising for further application.

Doping suppresses lattice distortion of vacant quadruple perovskites to activate self-trapped excitons emission

The vacancy-ordered quadruple perovskite Cs_(4)CdBi_(2)Cl_(12),as a newly-emerging lead-free perovskite system,has attracted great research interest due to its excellent stability and direct band gap.However,the poor luminescence performance limits its application in light-emitting diodes(LEDs)and other fields.Herein,for the first time,an Ag^(+)ion doping strategy was proposed to greatly improve the emission performance of Cs_(4)CdBi_(2)Cl_(12) synthesized by hydrothermal method.Density functional theory calculations combined with experimental results evidence that the weak orange emission from Cs_(4)CdBi_(2)Cl_(12) is attributed to the phonon scattering and energy level crossing due to the large lattice distortion under excited states.Fortunately,Ag^(+)ion doping breaks the intrinsic crystal field environment of Cs_(4)CdBi_(2)Cl_(12),suppresses the crossover between ground and excited states,and reduces the energy loss in the form of nonradiative recombination.At a critical doping amount of 0.8%,the emission intensity of Cs_(4)CdBi_(2)Cl_(12):Ag^(+)reaches the maximum,about eight times that of the pristine sample.Moreover,the doped Cs_(4)CdBi_(2)Cl_(12) still maintains excellent stability against heat,ultraviolet irradiation,and environmental oxygen/moisture.The above advantages make it possible for this material to be used as solid-state phosphors for white LEDs applications,and the Commission International de I’Eclairage color coordinates of(0.31,0.34)and high color rendering index of 90.6 were achieved.More importantly,the white LED demonstrates remarkable operation stability in air ambient,showing almost no emission decay after a long working time for 48 h.We believe that this study puts forward an effective ion-doping strategy for emission enhancement of vacancy-ordered quadruple perovskite Cs_(4)CdBi_(2)Cl_(12),highlighting its great potential as efficient emitter compatible for practical applications.

Holographic Storage Properties of In:Fe:Mn:LiNbO_3 Crystals

In：Fe：Mn：LiNbO3（LN） crystals were grown in air atmosphere by Czochralski method with different concentration of In （0, 1, 2, 3 mol%） in the melts, while the contents of Fe2O3 and MnO were 0.1 and 0.5 mol%, respectively. The location of doping ions was analyzed by Ultravioletvisible absorption spectra and differential thermal analysis. The diffraction efficiency （η）, writing time （τw） and erasure time （τe） of the crystals were measured by two-beam coupling experiment. The dynamic range and photorefractive sensitivity have also been calculated. The results showed that with the increase of In ions in the melt, the absorption edge of In：Fe：Mn：LN crystal shifts to the violet firstly and then makes the Einstein shift, the Curie temperature of crystal increases firstly and then decreases, the storage ratio speeds up, diffraction efficiency decreases, and dynamic range and photorefractive sensitivity increase. The mechanism of holographic storage properties of In：Fe： Mn：LN crystal with different doping concentration of In^3＋ was investigated, suggesting the In： Fe：Mn：LN crystals are excellent holographic storage materiel with better synthetical properties than Fe：Mn：LN crystals.

Study on the Growth and Photorefractive Properties of In:Fe:Cu:LiNbO_3 Crystals

Fe（0.2 mol%）：Cu（0.04 mol%）：LiNbO3 crystals with different doping concentration of In^3＋ （0, 1.0, 2.0, 3.0mol%） were grown by Czochralski method, and then oxidized and reduced. The infrared transmittance spectra of crystals were measured to investigate the location of doping ion and its threshold concentration. The photorefractive properties of the crystals were tested by two beam coupling experiment. The results showed that the threshold concentration of In ions is 2.0～ 3.0 mol% and In ions take the place of NbLi^4＋ to form （ InLi^2＋） before reaching its threshold concentration, and then the location of normal Nb ions. In the （2.0 mol%）：Fe：Cu：LiNbO3 crystal with the oxidation treatment having the highest diffraction efficiency （η = 45.8%）, the photo-damage resistance threshold value R of In（3.0 mol%）：Fe：Cu：LiNbO3 was 3.67×10^4 W/cm^2 which was two orders of magnitude higher than that of Fe：Cu：LiNbO3 crystal （4.30×10^2 W/cm^2）. And the photo-damage resistance ability was enhanced by oxidized treatment. The In（2.0～3.0 mol%）：Fe：Cu：LiNbO3 crystals with oxidized treatment have the best photorefractive properties.