In this study,a batch of φ12 mm Cs_(2)LiYCl_(6):Ce crystals codoped with different contents of Cu^(+)and Sc^(3+)was successfully grown using the Multi-ampule Bridgeman method.A new emission peaking at 418 nm is found...In this study,a batch of φ12 mm Cs_(2)LiYCl_(6):Ce crystals codoped with different contents of Cu^(+)and Sc^(3+)was successfully grown using the Multi-ampule Bridgeman method.A new emission peaking at 418 nm is found in the photoluminescence spectra of CLYC:Ce codoped with Cu^(+)ion.Codoping Cu^(+)or Sc^(3+)both increases the proportion of intrinsic self-trapped exciton(STE)luminescence,and extends the excitation band of Ce^(3+),especially in Cu^(+)codoped samples,where a new absorption peak at 248 nm can be identified.The light yield of Cu^(+)codoped samples remains largely unchanged,but the energy resolution shows a slight deterioration.Both light yield and energy resolution degrade after Sc^(3+)codoping,and the effect is much severe than that of Cu^(+)codoped samples.X-ray induced afterglow can be suppressed after Cu^(+)codoping and low content of Sc^(3+)codoping.The scintillation decay variation also depends on the codoping ions and their contents.展开更多
Diamond crystals were synthesized with different doping proportions of N-H-O at 5.5 GPa-7.1 GPa and 1370℃-1450℃. With the increase in the N-H-O doping ratio, the crystal growth rate decreased, the temperature and pr...Diamond crystals were synthesized with different doping proportions of N-H-O at 5.5 GPa-7.1 GPa and 1370℃-1450℃. With the increase in the N-H-O doping ratio, the crystal growth rate decreased, the temperature and pressure conditions required for diamond nucleation became increasingly stringent, and the diamond crystallization process was affected. [111] became the dominant plane of diamonds;surface morphology became block-like;and growth texture,stacking faults, and etch pits increased. The diamond crystals had a two-dimensional growth habit. Increasing the doping concentration also increased the amount of N that entered the diamond crystals as confirmed via Fourier transform infrared spectroscopy. However, crystal quality gradually deteriorated as verified by the red-shifting of Raman peak positions and the widening of the Raman full width at half maximum. With the increase in the doping ratio, the photoluminescence property of the diamond crystals also drastically changed. The intensity of the N vacancy center of the diamond crystals changed, and several Ni-related defect centers, such as the NE1 and NE3 centers, appeared. Diamond synthesis in N-H-O-bearing fluid provides important information for deepening our understanding of the growth characteristics of diamonds in complex systems and the formation mechanism of natural diamonds, which are almost always N-rich and full of various defect centers. Meanwhile, this study proved that the type of defect centers in diamond crystals could be regulated by controlling the N-H-O impurity contents of the synthesis system.展开更多
Catalyst design relies heavily on electronic metal‐support interactions,but the metal‐support interface with an uncontrollable electronic or coordination environment makes it challenging.Herein,we outline a promisin...Catalyst design relies heavily on electronic metal‐support interactions,but the metal‐support interface with an uncontrollable electronic or coordination environment makes it challenging.Herein,we outline a promising approach for the rational design of catalysts involving heteroatoms as anchors for Pd nanoparticles for ethanol oxidation reaction(EOR)catalysis.The doped B and N atoms from dimethylamine borane(DB)occupy the position of the Ti_(3)C_(2) lattice to anchor the supported Pd nanoparticles.The electrons transfer from the support to B atoms,and then to the metal Pd to form a stable electronic center.A strong electronic interaction can be produced and the d‐band center can be shifted down,driving Pd into the dominant metallic state and making Pd nanoparticles deposit uniformly on the support.As‐obtained Pd/DB–Ti_(3)C_(2) exhibits superior durability to its counterpart(∼14.6% retention)with 91.1% retention after 2000 cycles,placing it among the top single metal anodic catalysts.Further,in situ Raman and density functional theory computations confirm that Pd/DB–Ti_(3)C_(2) is capable of dehydrogenating ethanol at low reaction energies.展开更多
In this study, we have performed first-principles screened exchanged hybrid density function theory with the HSE06 function calculations of the C-Mo, C-W, N-Nb and N-Ta codoped anatase TiO2 systems to investigate the ...In this study, we have performed first-principles screened exchanged hybrid density function theory with the HSE06 function calculations of the C-Mo, C-W, N-Nb and N-Ta codoped anatase TiO2 systems to investigate the effect of codoping on the electronic structure of TiO2. The calculated results demonstrate that （W（s）＋C（s）） codoped TiO2 narrows the band gap significantly, and have little influence on the position of conduction band edges, therefore, enhances the efficiency of the photocatalytic hydrogen generation from water and the photodegradation of organic pollutants. Moreover, the proper oxygen pressure and temperature are two key factors during synthesis which should be carefully under control so that the desired （W（s）＋C（s）） codoped TiO2 can be obtained.展开更多
Mg_(3)Sb_(2)has attracted intensive attention as a typical Zintl-type thermoelectric material.Despite the exceptional thermoelectric performance in n-type Mg_(3)Sb_(2),the dimensionless figure of merit(zT)of p-type Mg...Mg_(3)Sb_(2)has attracted intensive attention as a typical Zintl-type thermoelectric material.Despite the exceptional thermoelectric performance in n-type Mg_(3)Sb_(2),the dimensionless figure of merit(zT)of p-type Mg_(3)Sb_(2)remains lower than 1,which is mainly attributed to its inferior electrical properties.Herein,we synergistically optimize the thermoelectric properties of p-type Mg_(3)Sb_(2)materials via codoping of Cd and Ag,which were synthesized by high-energy ball milling combined with hot pressing.It is found that Cd doping not only increases the carrier mobility of p-type Mg_(3)Sb_(2),but also diminishes its thermal conductivity(κ_(tot)),with Mg_(2.85)Cd_(0.5)Sb_(2)achieving a lowκtot value of∼0.67 W m^(−1)K^(−1)at room temperature.Further Ag doping elevates the carrier concentration,so that the power factor is optimized over the entire temperature range.Eventually,a peak zT of∼0.75 at 773 K and an excellent average zT of∼0.41 over 300−773 K are obtained in Mg_(2.82)Ag_(0.03)Cd_(0.5)Sb_(2),which are∼240%and∼490%higher than those of pristine Mg_(3.4)Sb_(2),respectively.This study provides an effective pathway to synergistically improve the thermoelectric performance of p-type Mg_(3)Sb_(2)by codoping Cd and Ag,which is beneficial to the future applications of Mg_(3)Sb_(2)-based thermoelectric materials.展开更多
In the iron-based high-To bulk superconductors, Tc above 50 K was only observed in the electron-doped 1111-type compounds. Here we revisit the electron-doped SmFeAsO polycrystals to make a further investigation for th...In the iron-based high-To bulk superconductors, Tc above 50 K was only observed in the electron-doped 1111-type compounds. Here we revisit the electron-doped SmFeAsO polycrystals to make a further investigation for the highest Tc in these materials. To introduce more electron carriers and less crystal lattice distortions, we study the Th and F eodoping effects into the Sm-O layers with heavy electron doping. Dozens of Sm1-xThx FeAsO1-yFy samples are synthesized through the solid state reaction method, and these samples are carefully characterized by the structural, resistive, and magnetic measurements. We find that the codoping of Th and F clearly enhances the superconducting Tc more than the Th or F single-doped samples, with the highest record Tc up to 58.6K when x = 0.2 and y=0.225. Further element doping causes more impurities and lattice distortions in the samples with a weakened superconductivity.展开更多
In this work, a simple method to modulate the crystal phase and morphology with a large amount of K＋ions codoping is proposed. The phase changes to the mixture of β-Na YF4 and β-KYF4 with increasing the content of...In this work, a simple method to modulate the crystal phase and morphology with a large amount of K＋ions codoping is proposed. The phase changes to the mixture of β-Na YF4 and β-KYF4 with increasing the content of K^＋ions to 80 mol%.When it exceeds 80 mol%, β-Na YF4 disappears gradually and β-KYF4 dominates with a poor crystalline. In addition, the morphology changes from nanosphere to nanoplate, and then to nanoprism, which indicates that a higher content of K^＋ions favors the growth rates along [0001] than the [10-10] of the nanocrystals. Additionally, the upconversion（UC） luminescence properties and the ratio of red/green（R/G） UC intensity of samples with different phases and morphologies are detected,which makes it possible to tune the UC fluorescence by varying the concentration of K^＋ions.展开更多
In this paper we present a novel report on the upconversion luminescence performance of NaY0.92Yb0.05Er0.03F4 enhanced by Zr^4＋ codoping. The luminescence intensity of the tridoped hexagonal NaYF_4 synthesized by a h...In this paper we present a novel report on the upconversion luminescence performance of NaY0.92Yb0.05Er0.03F4 enhanced by Zr^4＋ codoping. The luminescence intensity of the tridoped hexagonal NaYF_4 synthesized by a hydrothermal method increased to the maximum, about seven times of the non-Zr^4＋ sample when the Zr^4＋ codoping concentration rose to 6 mol%, while the luminescence lifetime was also prolonged by Zr^4＋ codoping. To explore the relationships between the microstructure and upconversion properties, X-ray powder diffraction, field emission scanning electron microscope, electron energy-dispersive spectroscopy and upconversion emission spectroscopy were employed. From these characterizations, we found that the codoping of Zr^4＋ could modulate the crystal microstructure of NaYF_4 for higher upconversion luminescence intensity and longer lifetime. This study may be helpful for the design and synthesis of high-performance upconversion materials.展开更多
The structural,electronic properties and formation energies of sulfur and alkaline earth codoped delafossite CuAlO_2 have been investigated using the first-principles density functional theory calculations.Our results...The structural,electronic properties and formation energies of sulfur and alkaline earth codoped delafossite CuAlO_2 have been investigated using the first-principles density functional theory calculations.Our results reveal that the volume of codoping systems increases with the increasing atomic radius of metal atoms.The formation energies under different growth conditions have been calculated,showing that the codoping systems are formed easily under O-rich growth conditions.Electronic band structures and density of states have been obtained.The decreased bandgaps,enhanced covalence and appearance of electron acceptors after codoping are all good for p-type conductivity.展开更多
Carbon-based materials have become a research hotspot in the field of energy storage devices in recent years due to their abundant resources,low cost,and environmental friendliness.However,the low capacity and poor hi...Carbon-based materials have become a research hotspot in the field of energy storage devices in recent years due to their abundant resources,low cost,and environmental friendliness.However,the low capacity and poor high rate performance still constitute great challenges.Metal organic framework-derived carbon has been widely researched because of its high porosity,tunable structure,and good conductivity.In this work,N/S codoped hierarchical porous carbon microspheres were prepared by a high-temperature heat treatment and atomic doping process using a zinc-based organic framework as the precursor.When used as a potassium-ion battery anode,it has a high reversible specific capacity(435.7 mAh g^(-1)),good rate performance(133.5 mAh g^(-1)at 10,000 m A g^(-1)),and long-term cycling stability(73.2%capacity retention after the 2500th cycle).The potassium storage mechanism of the derived carbon was explained by various electrochemical analysis methods and microstructure characterization techniques,and the relationship between the structural characteristics and electrochemical properties was researched.In a supercapacitor,the porous carbon material exhibits a specific capacitance of 307.2 F g^(-1)at a current density of 0.2 A g^(-1)in a KOH aqueous solution and achieves a retention rate of 99.88%after 10,000 cycles.The assembled symmetric supercapacitor device delivers a high energy density of 6.69 Wh kg^(-1),with a corresponding power density of 2500 W kg^(-1).In addition,density functional theory calculations further confirmed that N/S codoping can improve the adsorption capacities of potassium and hydroxyl ions in the derived carbon.展开更多
The electronic structure and optical properties of N and Fe codoping Ti02 have been investigated by first-principles calculations based on density functional theory. The calculated results indicate that the stability ...The electronic structure and optical properties of N and Fe codoping Ti02 have been investigated by first-principles calculations based on density functional theory. The calculated results indicate that the stability of N and Fe codoping TiO2 will change at different substitutional sites of N and Fe. The mechanism of band gap narrowing of doping Ti02 is discussed by investigating the density of state. The different substitutional site of N and Fe in codoping TiO2 influences the visible-light absorption. An increased visible-light absorption for doping TiO2 results from the synergistic effect of N and Fe codoping. Therefore, N and Fe codoping may enhance the visible-light photocatalytic activity of TiO2.展开更多
Infrared-to-visible upconverted luminescent spectra of Er3 t and La3 t codoped Y2O3 powders are investigated.By introducing La3 t ions, the upconversion green radiation is found to be greatly enhanced when compared wi...Infrared-to-visible upconverted luminescent spectra of Er3 t and La3 t codoped Y2O3 powders are investigated.By introducing La3 t ions, the upconversion green radiation is found to be greatly enhanced when compared with the powders with La3 t absent. Such enhancement can be attributed to the modification of the local symmetry surrounding the Er3 t ion, which benefits the intra-4f transitions of Er3 t ion, and the decreasing interaction between Er3 t ions, which suppresses the energy transfer process4F7∕2t 4I11∕2→ 4F9∕2t 4F9∕2.展开更多
With the support by the National Natural Science Foundation of China,the research teams led by Prof.Xu Xiaohong（许小红）at the School of Chemistry and Materials Science,Shanxi Normal University and Prof.Zhang Zhenyu ...With the support by the National Natural Science Foundation of China,the research teams led by Prof.Xu Xiaohong（许小红）at the School of Chemistry and Materials Science,Shanxi Normal University and Prof.Zhang Zhenyu at ICQD,University of Science and Technology of China used vanadium-iodine（Ⅴ-Ⅰ）codoped Sb2Te3 to realize high-temperature quantum anomalous Hall effect（QAHE）,which was展开更多
Owing to their unique optical properties and nontoxicity,lead-free halide double perovskite nanocrystals are of interest for widespread applications.Herein,the colloid synthesis and photoluminescenc e property of Ag^(...Owing to their unique optical properties and nontoxicity,lead-free halide double perovskite nanocrystals are of interest for widespread applications.Herein,the colloid synthesis and photoluminescenc e property of Ag^(+)-Eu^(3+)codoped Cs_(2)NaInCl_(6)nanocrystals were investigated.The pe rovskite nanocrystals exhibit a broad warm-white photo luminescence with correlated color temperature(CCT)of 3447 K and color rendering index(CRI)of 90.2,and the means of codoping would improve its optical performance.A fast energy transfer and a long-lived self-trapped excitons state are unveiled by the femtosecond transient absorption spectra.The fast energy transfer from the self-trapped excitons of host nanocrystals to the Eu^(3+)ions is helpful to achieve a broad photoluminescence,and the quantum yield of Cs_(2)NaInCl_(6):0.05Ag^(+)-Eu^(3+)anocrystals can be enha nced to 69.5%.There is a large exciton binding energy and strong electron-phonon interaction in the codoped perovskite nanocrystals.The efficient and excellent air-stable double perovskite nanocrystals would be considered as a single-component phosphor for warm-white lighting.展开更多
Co-V-Ga-based shape memory alloys have shown great potential in the field of solid-state elastocaloric refrigeration due to their low stress hysteresis(Δσ_(hys)) and excellent superelasticity.However,large applied s...Co-V-Ga-based shape memory alloys have shown great potential in the field of solid-state elastocaloric refrigeration due to their low stress hysteresis(Δσ_(hys)) and excellent superelasticity.However,large applied stress and low adiabatic temperature change(ΔT_(ad)) greatly limit the application of Co-V-Ga-based alloys as elastocaloric materials.Here,we have successfully achieved a breakthrough in material properties by innovatively introducing the co-doping strategy of Mn and Ti elements.It was found that the synergistic effect of Mn and Ti significantly enhanced the mechanical properties of the Co_(52)V_(31)Ga_(14)Mn_(1)Ti_(2) alloy through solid solution strengthening,fine grain strengthening,and precipitation strengthening mechanisms.A large ΔT_(ad) of-11 K was obtained for the Co_(52)V_(31)Ga_(14)Mn_(1)Ti_(2) bulk poly crystalline alloy under a very low applied stress of 380 MPa.This is mainly due to the strong texture of <001>A.Texture strengthening is the key factor to improve the elastocaloric effect of alloys.At the same time,the Co_(52)V_(31)Ga_(14)Mn_(1)Ti_(2) alloy still maintains a ΔT_(ad) of -4 K without an obvious attenuation trend after 350 elastocaloric cycles under the applied stress of 300 MPa.In addition,due to the low energy dissipation(ΔW),the energy conversion efficiency of the elastocaloric response is greatly improved,so that the coefficient of performance(COP) of the Co_(52)V_(31)Ga_(14)Mn_(1)Ti_(2) alloy material is as high as 28.9,far exceeding most of the current shape memory alloy elastocaloric materials.As a result,the co-doping of Mn and Ti elements makes it possible to prepare an elastocaloric refrigeration alloy with low applied stress and a large elastocaloric effect.展开更多
Magnetic and optical properties of ZnO co-doped with transition metal and carbon have been investigated using density functional theory based on first-principles ultrasoft pseudopoten- tial method. Upon co-doping with...Magnetic and optical properties of ZnO co-doped with transition metal and carbon have been investigated using density functional theory based on first-principles ultrasoft pseudopoten- tial method. Upon co-doping with transition metal （TM） and carbon, the calculated results show a shift in the Fermi level and a remarkable change in the covalency of ZnO. Such cases energetically favor ferromagnetic semiconductor with high Curie temperature due to p-d exchange interaction between TM ions and holes induced by C doping. The total en- ergy difference between the ferromagnetic and the antiferromagnetic configurations, spatial charge and spin density, which determine the magnetic ordering, were calculated in co-doped systems for further analysis of magnetic properties. It was also discovered that optical prop- erties in the higher energy region remain relatively unchanged while those at the low energy region are changed after the co-doping. These changes of optical properties are qualitatively explained based on the calculated electronic structure. The validity of our calculation in comparison with other theoretical predictions will further motivate the experimental inves- tigation of （TM, C） co-doped ZnO diluted magnetic semiconductors.展开更多
Codoping approach is an appealing strategy to further improve the catalytic activity of Ce-based catalysts.In the present study,Mn and/or Cu doped ceria solid solutions MnxCuyCe1-x-yO2,CuxCe1-xO2,MnxCe1-xO2 and pure C...Codoping approach is an appealing strategy to further improve the catalytic activity of Ce-based catalysts.In the present study,Mn and/or Cu doped ceria solid solutions MnxCuyCe1-x-yO2,CuxCe1-xO2,MnxCe1-xO2 and pure CeO2 were prepared by CTAB-assisted hydrothermal method for CO oxidation.XRD,SEM,EDS,BET,Raman,H2-TPR,XPS and in situ DRIFTS techniques were carried out to study the physicochemical properties and to correlate them to the activity.The doped samples maintain the cubic fluorite structure of CeO2 with high crystallinity and small crystallite size,forming Ce-based solid solutions.The obtained catalysts have large mesoporous structure with average pore size of 10-14 nm.The doped transition metal enhances the oxygen vacancies and improves reducibility of the solids.The synergistic interaction of Mn and Cu codoping induces mo re oxygen vacancies,pro moting the increase of surface adsorbed oxygen and the transfer of bulk oxygen of catalyst,thereby enhancing the catalytic activity for CO oxidation.Besides,the decomposition rate of the carbonate species which is derived from in situ DRIFTS for each catalyst can provide a measure to evaluate its catalytic activity of CO oxidation.展开更多
The impact of N-and X（X=S,Se,Te）-codoping on electronic properties of anatase TiO2 has been systematically investigated using density functional theory （DFT）.The optimized geometry shows that there is large lattic...The impact of N-and X（X=S,Se,Te）-codoping on electronic properties of anatase TiO2 has been systematically investigated using density functional theory （DFT）.The optimized geometry shows that there is large lattice expansion for the codoped anatase TiO2 due to large atomic radius of the codoped atom.The calculated substitution energies indicate that incorporation of X（X =S,Se,Te） into N-doped bulk TiO2 can not promote synergistic effect on N after substituting for Ti,whcreas it is bctter after substituting for O.According to the total density of states （DOS） and corresponding partial DOS （PDOS）,it can be seen that substituting X（X =S,Se,Te） for O,N 2p orbital is strongly hybridized with impurity states （S 3p,Se 4p,Te 5p）.After substituting X（X=S,Se,Te） for Ti,conduction band is mainly dominated by Ti 3d orbit and S 3p （Se 4p or Te 5p）-N 2p-Ti 3d hybridized states are formed.Based on Bader analysis,it can be indicated that the electron transfer is from N to X（X=S,Se,Te） if substituting X（X=S,Se,Te） for O,but it is opposite if substitute X（X=S,Se,Te） for Ti.展开更多
Porous C‐I codoped carbon nitride materials were synthesized by in‐situ codoping with iodized ionic liquid followed by post‐thermal treatment in air.The effects of doping content of C‐I codoping with different amo...Porous C‐I codoped carbon nitride materials were synthesized by in‐situ codoping with iodized ionic liquid followed by post‐thermal treatment in air.The effects of doping content of C‐I codoping with different amounts of ionic liquid on the structural,optical and photocatalytic properties of the samples were investigated.Characterization results show that more compact interlayer sacking can be achieved by post‐thermal treatment.Combined with C‐I codoping by insertion of ionic liquids,much enlarged surface area but optimized sp2 conjugated heterocyclic structure can be found in the catalysts.Optical and energy band analysis results evidence that the light absorptions especially in visible light region are significantly improved.Although the band gap of porous C‐I codoped samples enlarge because of the generation of porous,the negatively shifted conduction band position thermodynamically supplies stronger motivation for water reduction.Photoelectricity tests reveal that the photo‐induced electron density was increased after C‐I codoping modification.Also,the recombination rate of electron‐hole pairs is remarkably inhibited.The catalysts with moderate C‐I codoing content perform sharply enhanced photocatalytic H2 evolution activity under visible light irradiation.A H2 evolution rate of 168.2μmol/h was achieved and it was more than 9.8 times higher than pristine carbon nitride.This study demonstrates a novel non‐metal doping strategy for synthesis and optimization of polymer semiconductor with gratifying photocatalytic H2 evolution performance from water hydrolysis.展开更多
A series of La/Ce-codoped Bi2O3 composite photocatalysts were fabricated via hydrothermal–calcination process. The as-prepared products were intensively characterized by some physicochemical characterizations like N2...A series of La/Ce-codoped Bi2O3 composite photocatalysts were fabricated via hydrothermal–calcination process. The as-prepared products were intensively characterized by some physicochemical characterizations like N2 physical adsorption, X-ray powder diffraction（XRD）, scanning electron microscope（SEM）, transmission electron microscope（TEM）, UV–Vis diffuse reflectance（UV–Vis DRS）, Fourier transform infrared spectroscopy（FT-IR）,photoelectrochemical measurements, and photoluminescence（PL） spectroscopy. The characterization results indicated that La and Ce doping induced obvious crystal phase transformation in Bi2O3, from monoclinic to tetragonal phase. La and Ce codoping also gave rise to the obvious synergetic effects, e.g., the lattice contraction of Bi2O3, the decrease of crystal size and the increase of surface area. The photocatalytic performance of the prepared catalysts was evaluated by removal of dye acid orange II with high concentration under visible light irradiation. Results showed that La/Ce-codoped Bi2O3 displayed much higher photocatalytic performance than that of bare Bi2O3, single La or Ce doped Bi2O3 samples. The superior photocatalytic activity was mainly attributed to the improved texture and surface properties and the synergistic effects of La and Ce codoping on suppressing the recombination of photo-generated electrons（e^-） and holes（h~＋）.展开更多
基金Project supported by the National Key Research and Development Program,China(2022YFB3503600)Manned Space Station Engineering Space Science and Applications Program(MSAP)(ZDBS-ZRKJZTLC011)+3 种基金National Natural Science Foundation of China,China(11975303,12211530561,12305211)Shanghai Municipal Natural Science Foundation,China(21TS1400100)CAS Cooperative Research Project(121631KYSB20210017)CAS Project for Young Scientist in Basic Research(YSBR-024)。
文摘In this study,a batch of φ12 mm Cs_(2)LiYCl_(6):Ce crystals codoped with different contents of Cu^(+)and Sc^(3+)was successfully grown using the Multi-ampule Bridgeman method.A new emission peaking at 418 nm is found in the photoluminescence spectra of CLYC:Ce codoped with Cu^(+)ion.Codoping Cu^(+)or Sc^(3+)both increases the proportion of intrinsic self-trapped exciton(STE)luminescence,and extends the excitation band of Ce^(3+),especially in Cu^(+)codoped samples,where a new absorption peak at 248 nm can be identified.The light yield of Cu^(+)codoped samples remains largely unchanged,but the energy resolution shows a slight deterioration.Both light yield and energy resolution degrade after Sc^(3+)codoping,and the effect is much severe than that of Cu^(+)codoped samples.X-ray induced afterglow can be suppressed after Cu^(+)codoping and low content of Sc^(3+)codoping.The scintillation decay variation also depends on the codoping ions and their contents.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 51772120, 11604246, 51872112, and 11804305)the Project of Jilin Science and Technology Development Plan (Grant No. 20180201079GX)+1 种基金the Fundamental Research Funds for the Central Universities, the Natural Science Foundation of Chongqing, China (Grant No. cstc2019jcyj-msxm X0391)the Science and Technology Research Program of Chongqing Municipal Education Commission (Grant No. KJQN201901405)。
文摘Diamond crystals were synthesized with different doping proportions of N-H-O at 5.5 GPa-7.1 GPa and 1370℃-1450℃. With the increase in the N-H-O doping ratio, the crystal growth rate decreased, the temperature and pressure conditions required for diamond nucleation became increasingly stringent, and the diamond crystallization process was affected. [111] became the dominant plane of diamonds;surface morphology became block-like;and growth texture,stacking faults, and etch pits increased. The diamond crystals had a two-dimensional growth habit. Increasing the doping concentration also increased the amount of N that entered the diamond crystals as confirmed via Fourier transform infrared spectroscopy. However, crystal quality gradually deteriorated as verified by the red-shifting of Raman peak positions and the widening of the Raman full width at half maximum. With the increase in the doping ratio, the photoluminescence property of the diamond crystals also drastically changed. The intensity of the N vacancy center of the diamond crystals changed, and several Ni-related defect centers, such as the NE1 and NE3 centers, appeared. Diamond synthesis in N-H-O-bearing fluid provides important information for deepening our understanding of the growth characteristics of diamonds in complex systems and the formation mechanism of natural diamonds, which are almost always N-rich and full of various defect centers. Meanwhile, this study proved that the type of defect centers in diamond crystals could be regulated by controlling the N-H-O impurity contents of the synthesis system.
基金Key Research and Development Program of Zhejiang,Grant/Award Number:2021C03022National Natural Science Foundation of China,Grant/Award Numbers:22002104,22272115,22202145,22202146,22102112,22202147。
文摘Catalyst design relies heavily on electronic metal‐support interactions,but the metal‐support interface with an uncontrollable electronic or coordination environment makes it challenging.Herein,we outline a promising approach for the rational design of catalysts involving heteroatoms as anchors for Pd nanoparticles for ethanol oxidation reaction(EOR)catalysis.The doped B and N atoms from dimethylamine borane(DB)occupy the position of the Ti_(3)C_(2) lattice to anchor the supported Pd nanoparticles.The electrons transfer from the support to B atoms,and then to the metal Pd to form a stable electronic center.A strong electronic interaction can be produced and the d‐band center can be shifted down,driving Pd into the dominant metallic state and making Pd nanoparticles deposit uniformly on the support.As‐obtained Pd/DB–Ti_(3)C_(2) exhibits superior durability to its counterpart(∼14.6% retention)with 91.1% retention after 2000 cycles,placing it among the top single metal anodic catalysts.Further,in situ Raman and density functional theory computations confirm that Pd/DB–Ti_(3)C_(2) is capable of dehydrogenating ethanol at low reaction energies.
基金supported by the NKBRSF (2007CB815202)NKBRSF (No. 2009CB220010)+2 种基金NSFC (20833008)NSFC (No. 20973168)the Solar Energy Initiative of the Knowledge Innovation Program of the Chinese Academy of Science (No. KGCX2-YW-394-2)
文摘In this study, we have performed first-principles screened exchanged hybrid density function theory with the HSE06 function calculations of the C-Mo, C-W, N-Nb and N-Ta codoped anatase TiO2 systems to investigate the effect of codoping on the electronic structure of TiO2. The calculated results demonstrate that （W（s）＋C（s）） codoped TiO2 narrows the band gap significantly, and have little influence on the position of conduction band edges, therefore, enhances the efficiency of the photocatalytic hydrogen generation from water and the photodegradation of organic pollutants. Moreover, the proper oxygen pressure and temperature are two key factors during synthesis which should be carefully under control so that the desired （W（s）＋C（s）） codoped TiO2 can be obtained.
基金financially supported by the National Natural Science Foundation of China (Grant No. 52071041, 11874356, 51802034)supported by the Key Research Program of Frontier Sciences, CAS (Grant No.QYZDB-SSW-SLH016)
文摘Mg_(3)Sb_(2)has attracted intensive attention as a typical Zintl-type thermoelectric material.Despite the exceptional thermoelectric performance in n-type Mg_(3)Sb_(2),the dimensionless figure of merit(zT)of p-type Mg_(3)Sb_(2)remains lower than 1,which is mainly attributed to its inferior electrical properties.Herein,we synergistically optimize the thermoelectric properties of p-type Mg_(3)Sb_(2)materials via codoping of Cd and Ag,which were synthesized by high-energy ball milling combined with hot pressing.It is found that Cd doping not only increases the carrier mobility of p-type Mg_(3)Sb_(2),but also diminishes its thermal conductivity(κ_(tot)),with Mg_(2.85)Cd_(0.5)Sb_(2)achieving a lowκtot value of∼0.67 W m^(−1)K^(−1)at room temperature.Further Ag doping elevates the carrier concentration,so that the power factor is optimized over the entire temperature range.Eventually,a peak zT of∼0.75 at 773 K and an excellent average zT of∼0.41 over 300−773 K are obtained in Mg_(2.82)Ag_(0.03)Cd_(0.5)Sb_(2),which are∼240%and∼490%higher than those of pristine Mg_(3.4)Sb_(2),respectively.This study provides an effective pathway to synergistically improve the thermoelectric performance of p-type Mg_(3)Sb_(2)by codoping Cd and Ag,which is beneficial to the future applications of Mg_(3)Sb_(2)-based thermoelectric materials.
基金Supported by the National Natural Science Foundation of China under Grant No 11474339the National Basic Research Program of China under Grant No 2016YFA0300301the Youth Innovation Promotion Association of the Chinese Academy of Sciences
文摘In the iron-based high-To bulk superconductors, Tc above 50 K was only observed in the electron-doped 1111-type compounds. Here we revisit the electron-doped SmFeAsO polycrystals to make a further investigation for the highest Tc in these materials. To introduce more electron carriers and less crystal lattice distortions, we study the Th and F eodoping effects into the Sm-O layers with heavy electron doping. Dozens of Sm1-xThx FeAsO1-yFy samples are synthesized through the solid state reaction method, and these samples are carefully characterized by the structural, resistive, and magnetic measurements. We find that the codoping of Th and F clearly enhances the superconducting Tc more than the Th or F single-doped samples, with the highest record Tc up to 58.6K when x = 0.2 and y=0.225. Further element doping causes more impurities and lattice distortions in the samples with a weakened superconductivity.
基金supported by the National High Technology Research and Development Program of China(Grant No.2013AA032205)the National Natural Science Foundation of China(Grant No.51272022)the Fundamental Research Funds for the Central Universities,China(Grant No.2012JBZ001)
文摘In this work, a simple method to modulate the crystal phase and morphology with a large amount of K＋ions codoping is proposed. The phase changes to the mixture of β-Na YF4 and β-KYF4 with increasing the content of K^＋ions to 80 mol%.When it exceeds 80 mol%, β-Na YF4 disappears gradually and β-KYF4 dominates with a poor crystalline. In addition, the morphology changes from nanosphere to nanoplate, and then to nanoprism, which indicates that a higher content of K^＋ions favors the growth rates along [0001] than the [10-10] of the nanocrystals. Additionally, the upconversion（UC） luminescence properties and the ratio of red/green（R/G） UC intensity of samples with different phases and morphologies are detected,which makes it possible to tune the UC fluorescence by varying the concentration of K^＋ions.
基金supported by the National Natural Science Foundation of China(No.51102047,51472050)State Key Laboratory of Photocatalysis on Energy and Environment Open Project
文摘In this paper we present a novel report on the upconversion luminescence performance of NaY0.92Yb0.05Er0.03F4 enhanced by Zr^4＋ codoping. The luminescence intensity of the tridoped hexagonal NaYF_4 synthesized by a hydrothermal method increased to the maximum, about seven times of the non-Zr^4＋ sample when the Zr^4＋ codoping concentration rose to 6 mol%, while the luminescence lifetime was also prolonged by Zr^4＋ codoping. To explore the relationships between the microstructure and upconversion properties, X-ray powder diffraction, field emission scanning electron microscope, electron energy-dispersive spectroscopy and upconversion emission spectroscopy were employed. From these characterizations, we found that the codoping of Zr^4＋ could modulate the crystal microstructure of NaYF_4 for higher upconversion luminescence intensity and longer lifetime. This study may be helpful for the design and synthesis of high-performance upconversion materials.
基金Supported by the National Natural Science Foundation of China under Grant Nos.11347199,51402244,and 11547311the Specialized Research Fund for Doctoral Program of Higher Education of China under Grant No.20130184120028+2 种基金the Fundamental Research Fund for the Central UniversitiesChina under Grant Nos.2682014CX084,2682014ZT30,and 2682014ZT31the fund of the State Key Laboratory of Solidification Processing in NWPU under Grant No.SKLSP201511
文摘The structural,electronic properties and formation energies of sulfur and alkaline earth codoped delafossite CuAlO_2 have been investigated using the first-principles density functional theory calculations.Our results reveal that the volume of codoping systems increases with the increasing atomic radius of metal atoms.The formation energies under different growth conditions have been calculated,showing that the codoping systems are formed easily under O-rich growth conditions.Electronic band structures and density of states have been obtained.The decreased bandgaps,enhanced covalence and appearance of electron acceptors after codoping are all good for p-type conductivity.
基金supported by the National Natural Science Foundation of China (51764029, 52004116)the National Key Research and Development Program of China (2019YFC1803501)+1 种基金the Applied Basic Research Plan of Yunnan Province(202001AU070039, 2018FB087)the Science Research Foundation of Yunnan Provincial Department of Education (2020J0070)
文摘Carbon-based materials have become a research hotspot in the field of energy storage devices in recent years due to their abundant resources,low cost,and environmental friendliness.However,the low capacity and poor high rate performance still constitute great challenges.Metal organic framework-derived carbon has been widely researched because of its high porosity,tunable structure,and good conductivity.In this work,N/S codoped hierarchical porous carbon microspheres were prepared by a high-temperature heat treatment and atomic doping process using a zinc-based organic framework as the precursor.When used as a potassium-ion battery anode,it has a high reversible specific capacity(435.7 mAh g^(-1)),good rate performance(133.5 mAh g^(-1)at 10,000 m A g^(-1)),and long-term cycling stability(73.2%capacity retention after the 2500th cycle).The potassium storage mechanism of the derived carbon was explained by various electrochemical analysis methods and microstructure characterization techniques,and the relationship between the structural characteristics and electrochemical properties was researched.In a supercapacitor,the porous carbon material exhibits a specific capacitance of 307.2 F g^(-1)at a current density of 0.2 A g^(-1)in a KOH aqueous solution and achieves a retention rate of 99.88%after 10,000 cycles.The assembled symmetric supercapacitor device delivers a high energy density of 6.69 Wh kg^(-1),with a corresponding power density of 2500 W kg^(-1).In addition,density functional theory calculations further confirmed that N/S codoping can improve the adsorption capacities of potassium and hydroxyl ions in the derived carbon.
基金Project supported by the National Natural Science Foundation of China(No.11005050)the Graduate Innovation Project of Jiangsu Province(No.SJLX_0517)
文摘The electronic structure and optical properties of N and Fe codoping Ti02 have been investigated by first-principles calculations based on density functional theory. The calculated results indicate that the stability of N and Fe codoping TiO2 will change at different substitutional sites of N and Fe. The mechanism of band gap narrowing of doping Ti02 is discussed by investigating the density of state. The different substitutional site of N and Fe in codoping TiO2 influences the visible-light absorption. An increased visible-light absorption for doping TiO2 results from the synergistic effect of N and Fe codoping. Therefore, N and Fe codoping may enhance the visible-light photocatalytic activity of TiO2.
基金financially supported by the Nature Science Foundation of Zhejiang Province under Grant No.LQ13F050003
文摘Infrared-to-visible upconverted luminescent spectra of Er3 t and La3 t codoped Y2O3 powders are investigated.By introducing La3 t ions, the upconversion green radiation is found to be greatly enhanced when compared with the powders with La3 t absent. Such enhancement can be attributed to the modification of the local symmetry surrounding the Er3 t ion, which benefits the intra-4f transitions of Er3 t ion, and the decreasing interaction between Er3 t ions, which suppresses the energy transfer process4F7∕2t 4I11∕2→ 4F9∕2t 4F9∕2.
文摘With the support by the National Natural Science Foundation of China,the research teams led by Prof.Xu Xiaohong（许小红）at the School of Chemistry and Materials Science,Shanxi Normal University and Prof.Zhang Zhenyu at ICQD,University of Science and Technology of China used vanadium-iodine（Ⅴ-Ⅰ）codoped Sb2Te3 to realize high-temperature quantum anomalous Hall effect（QAHE）,which was
基金Project supported by the National Natural Science Foundation of China(61805134,11974229,22303044)Fundamental Research Program of Shanxi Province(202203021221121)+3 种基金China Postdoctoral Science Foundation(2022M711898)Natural Science Fo undation of Shandong Province(ZR2023QB135)Postdoctoral Innovation Project of Shandong Province(SDCX-ZG-202201004)Graduate Innovation Project in Shanxi Province(2024KY450)。
文摘Owing to their unique optical properties and nontoxicity,lead-free halide double perovskite nanocrystals are of interest for widespread applications.Herein,the colloid synthesis and photoluminescenc e property of Ag^(+)-Eu^(3+)codoped Cs_(2)NaInCl_(6)nanocrystals were investigated.The pe rovskite nanocrystals exhibit a broad warm-white photo luminescence with correlated color temperature(CCT)of 3447 K and color rendering index(CRI)of 90.2,and the means of codoping would improve its optical performance.A fast energy transfer and a long-lived self-trapped excitons state are unveiled by the femtosecond transient absorption spectra.The fast energy transfer from the self-trapped excitons of host nanocrystals to the Eu^(3+)ions is helpful to achieve a broad photoluminescence,and the quantum yield of Cs_(2)NaInCl_(6):0.05Ag^(+)-Eu^(3+)anocrystals can be enha nced to 69.5%.There is a large exciton binding energy and strong electron-phonon interaction in the codoped perovskite nanocrystals.The efficient and excellent air-stable double perovskite nanocrystals would be considered as a single-component phosphor for warm-white lighting.
基金financially supported by the National Natural Science Foundation of China(Nos.52271172 and 51971085)Heilongjiang Provincial Natural Science Foundation of China(No.LH2024E075)
文摘Co-V-Ga-based shape memory alloys have shown great potential in the field of solid-state elastocaloric refrigeration due to their low stress hysteresis(Δσ_(hys)) and excellent superelasticity.However,large applied stress and low adiabatic temperature change(ΔT_(ad)) greatly limit the application of Co-V-Ga-based alloys as elastocaloric materials.Here,we have successfully achieved a breakthrough in material properties by innovatively introducing the co-doping strategy of Mn and Ti elements.It was found that the synergistic effect of Mn and Ti significantly enhanced the mechanical properties of the Co_(52)V_(31)Ga_(14)Mn_(1)Ti_(2) alloy through solid solution strengthening,fine grain strengthening,and precipitation strengthening mechanisms.A large ΔT_(ad) of-11 K was obtained for the Co_(52)V_(31)Ga_(14)Mn_(1)Ti_(2) bulk poly crystalline alloy under a very low applied stress of 380 MPa.This is mainly due to the strong texture of <001>A.Texture strengthening is the key factor to improve the elastocaloric effect of alloys.At the same time,the Co_(52)V_(31)Ga_(14)Mn_(1)Ti_(2) alloy still maintains a ΔT_(ad) of -4 K without an obvious attenuation trend after 350 elastocaloric cycles under the applied stress of 300 MPa.In addition,due to the low energy dissipation(ΔW),the energy conversion efficiency of the elastocaloric response is greatly improved,so that the coefficient of performance(COP) of the Co_(52)V_(31)Ga_(14)Mn_(1)Ti_(2) alloy material is as high as 28.9,far exceeding most of the current shape memory alloy elastocaloric materials.As a result,the co-doping of Mn and Ti elements makes it possible to prepare an elastocaloric refrigeration alloy with low applied stress and a large elastocaloric effect.
文摘Magnetic and optical properties of ZnO co-doped with transition metal and carbon have been investigated using density functional theory based on first-principles ultrasoft pseudopoten- tial method. Upon co-doping with transition metal （TM） and carbon, the calculated results show a shift in the Fermi level and a remarkable change in the covalency of ZnO. Such cases energetically favor ferromagnetic semiconductor with high Curie temperature due to p-d exchange interaction between TM ions and holes induced by C doping. The total en- ergy difference between the ferromagnetic and the antiferromagnetic configurations, spatial charge and spin density, which determine the magnetic ordering, were calculated in co-doped systems for further analysis of magnetic properties. It was also discovered that optical prop- erties in the higher energy region remain relatively unchanged while those at the low energy region are changed after the co-doping. These changes of optical properties are qualitatively explained based on the calculated electronic structure. The validity of our calculation in comparison with other theoretical predictions will further motivate the experimental inves- tigation of （TM, C） co-doped ZnO diluted magnetic semiconductors.
基金Project supported by the National Natural Science Foundation of China(21777055)Shandong Provincial Natural Science Foundation(ZR2017BB004)+1 种基金Shandong Province Key Research and Development Plan(2017GGX202004)Shandong Province Major Science and Technology Innovation Project(2017CXGC1004)
文摘Codoping approach is an appealing strategy to further improve the catalytic activity of Ce-based catalysts.In the present study,Mn and/or Cu doped ceria solid solutions MnxCuyCe1-x-yO2,CuxCe1-xO2,MnxCe1-xO2 and pure CeO2 were prepared by CTAB-assisted hydrothermal method for CO oxidation.XRD,SEM,EDS,BET,Raman,H2-TPR,XPS and in situ DRIFTS techniques were carried out to study the physicochemical properties and to correlate them to the activity.The doped samples maintain the cubic fluorite structure of CeO2 with high crystallinity and small crystallite size,forming Ce-based solid solutions.The obtained catalysts have large mesoporous structure with average pore size of 10-14 nm.The doped transition metal enhances the oxygen vacancies and improves reducibility of the solids.The synergistic interaction of Mn and Cu codoping induces mo re oxygen vacancies,pro moting the increase of surface adsorbed oxygen and the transfer of bulk oxygen of catalyst,thereby enhancing the catalytic activity for CO oxidation.Besides,the decomposition rate of the carbonate species which is derived from in situ DRIFTS for each catalyst can provide a measure to evaluate its catalytic activity of CO oxidation.
基金Natural Science Foundation of Shanxi Province(No.2009011014)
文摘The impact of N-and X（X=S,Se,Te）-codoping on electronic properties of anatase TiO2 has been systematically investigated using density functional theory （DFT）.The optimized geometry shows that there is large lattice expansion for the codoped anatase TiO2 due to large atomic radius of the codoped atom.The calculated substitution energies indicate that incorporation of X（X =S,Se,Te） into N-doped bulk TiO2 can not promote synergistic effect on N after substituting for Ti,whcreas it is bctter after substituting for O.According to the total density of states （DOS） and corresponding partial DOS （PDOS）,it can be seen that substituting X（X =S,Se,Te） for O,N 2p orbital is strongly hybridized with impurity states （S 3p,Se 4p,Te 5p）.After substituting X（X=S,Se,Te） for Ti,conduction band is mainly dominated by Ti 3d orbit and S 3p （Se 4p or Te 5p）-N 2p-Ti 3d hybridized states are formed.Based on Bader analysis,it can be indicated that the electron transfer is from N to X（X=S,Se,Te） if substituting X（X=S,Se,Te） for O,but it is opposite if substitute X（X=S,Se,Te） for Ti.
基金the National Natural Science Foundation of China(21503096,21407067)the Natural Science Foundation of Jiangsu Province(BK20140506)~~
文摘Porous C‐I codoped carbon nitride materials were synthesized by in‐situ codoping with iodized ionic liquid followed by post‐thermal treatment in air.The effects of doping content of C‐I codoping with different amounts of ionic liquid on the structural,optical and photocatalytic properties of the samples were investigated.Characterization results show that more compact interlayer sacking can be achieved by post‐thermal treatment.Combined with C‐I codoping by insertion of ionic liquids,much enlarged surface area but optimized sp2 conjugated heterocyclic structure can be found in the catalysts.Optical and energy band analysis results evidence that the light absorptions especially in visible light region are significantly improved.Although the band gap of porous C‐I codoped samples enlarge because of the generation of porous,the negatively shifted conduction band position thermodynamically supplies stronger motivation for water reduction.Photoelectricity tests reveal that the photo‐induced electron density was increased after C‐I codoping modification.Also,the recombination rate of electron‐hole pairs is remarkably inhibited.The catalysts with moderate C‐I codoing content perform sharply enhanced photocatalytic H2 evolution activity under visible light irradiation.A H2 evolution rate of 168.2μmol/h was achieved and it was more than 9.8 times higher than pristine carbon nitride.This study demonstrates a novel non‐metal doping strategy for synthesis and optimization of polymer semiconductor with gratifying photocatalytic H2 evolution performance from water hydrolysis.
基金supported by the National Natural Science Foundation of China (Nos. 21567008, 21607064, 21263005)the Natural Science Foundation of Jiangxi Province (No. 20161BAB203090)the Program of Qingjiang Excellent Young Talents, Jiangxi University of Science and Technology,the Landing Project of Science and Technology of Colleges and Universities in Jiangxi Province China (No. KJLD14046)
文摘A series of La/Ce-codoped Bi2O3 composite photocatalysts were fabricated via hydrothermal–calcination process. The as-prepared products were intensively characterized by some physicochemical characterizations like N2 physical adsorption, X-ray powder diffraction（XRD）, scanning electron microscope（SEM）, transmission electron microscope（TEM）, UV–Vis diffuse reflectance（UV–Vis DRS）, Fourier transform infrared spectroscopy（FT-IR）,photoelectrochemical measurements, and photoluminescence（PL） spectroscopy. The characterization results indicated that La and Ce doping induced obvious crystal phase transformation in Bi2O3, from monoclinic to tetragonal phase. La and Ce codoping also gave rise to the obvious synergetic effects, e.g., the lattice contraction of Bi2O3, the decrease of crystal size and the increase of surface area. The photocatalytic performance of the prepared catalysts was evaluated by removal of dye acid orange II with high concentration under visible light irradiation. Results showed that La/Ce-codoped Bi2O3 displayed much higher photocatalytic performance than that of bare Bi2O3, single La or Ce doped Bi2O3 samples. The superior photocatalytic activity was mainly attributed to the improved texture and surface properties and the synergistic effects of La and Ce codoping on suppressing the recombination of photo-generated electrons（e^-） and holes（h~＋）.
