Carbon materials are effective substitutes for Pt counter electrodes(CEs) in dye-sensitized solar cells(DSSCs). However, many of these materials, such as carbon nanotubes and graphene, are expensive and require comple...Carbon materials are effective substitutes for Pt counter electrodes(CEs) in dye-sensitized solar cells(DSSCs). However, many of these materials, such as carbon nanotubes and graphene, are expensive and require complex preparation process. Herein, waste lignin, recycled from hazardous black liquors,is used to create oxygen-nitrogen-sulfur codoped carbon microspheres for use in DSSC CEs through the facile process of low-temperature preoxidation and high-temperature self-activation. The large number of ester bonds formed by preoxidation increase the degree of cross-linking of the lignin chains, leading to the formation of highly disordered carbon with ample defect sites during pyrolysis. The presence of organic O/N/S components in the waste lignin results in high O/N/S doping of the pyrolysed carbon,which increases the electrolyte ion adsorption and accelerates the electron transfer at the CE/electrolyte interface, as confirmed by density functional theory(DFT) calculations. The presence of inorganic impurities enables the construction of a hierarchical micropore-rich carbon structure through the etching effect during self-activation, which can provide abundant catalytically active sites for the reversible adsorption/desorption of electrolyte ions. Under these synergistic effects, the DSSCs that use this novel carbon CE achieve a quite high power-conversion efficiency of 9.22%. To the best of our knowledge, the value is a new record reported so far for biomass-carbon-based DSSCs.展开更多
Doping with various impurities is an effective approach to improve the photoelectrochemical properties of TiO2. Here, we explore the effect of oxygen vacancy on geometric and elec- tronic properties of compensated （i...Doping with various impurities is an effective approach to improve the photoelectrochemical properties of TiO2. Here, we explore the effect of oxygen vacancy on geometric and elec- tronic properties of compensated （i.e. V-N and Cr-C） and non-compensated （i.e. V-C and Cr-N） codoped anatase TiO2 by performing extensive density functional theory calculations. Theoretical results show that oxygen vacancy prefers to the neighboring site of metal dopant （i.e. V or Cr atom）. After introduction of oxygen vacancy, the unoccupied impurity bands located within band gap of these codoped TiO2 will be filled with electrons, and the posi- tion of conduction band offset does not change obviously, which result in the reduction of photoinduced carrier recombination and the good performance for hydrogen production via water splitting. Moreover, we find that oxygen vacancy is easily introduced in V-N codoped TiO2 under O-poor condition. These theoretical insights are helpful for designing codoped TiO2 with high photoelectrochemical performance.展开更多
Carbon materials have shown remarkable usefulness in facilitating the performance of insulating sulfur cathode for lithium–sulfur batteries owing to their excellent conductivity and porous structure. However,the anxi...Carbon materials have shown remarkable usefulness in facilitating the performance of insulating sulfur cathode for lithium–sulfur batteries owing to their excellent conductivity and porous structure. However,the anxiety is the poor affinity toward polar polysulfides due to the intrinsic nonpolar surface of carbon.Herein, we report a direct pyrolysis of the mixture urea and boric acid to synthesize B/N–codoped hierarchically porous carbon nanosheets(B–N–CSs) as efficient sulfur host for lithium–sulfur battery. The graphene–like B–N–CSs provides high specific surface area and porous structure with abundant micropores(1.1 nm) and low–range mesopores(2.3 nm), thereby constraining the sulfur active materials within the pores. More importantly, the codoped B/N elements can further enhance the polysulfide confinement through strong Li–N and B–S interaction based on the Lewis acid–base theory. These structural superiorities significantly suppress the shuttle effect by both physical confinement and chemical interaction, and promote the redox kinetics of polysulfide conversion. When evaluated as the cathode host, the S/B–N–CSs composite displays the excellent performance with a high reversible capacity up to 772 m A h g–1 at 0.5 C and a low fading rate of ^0.09% per cycle averaged upon 500 cycles. In particular, remarkable stability with a high capacity retention of 87.1% can be realized when augmenting the sulfur loading in the cathode up to 4.6 mg cm^(-2).展开更多
Novel oxyfluoride glasses are developed with the composition of 30SiO2-15Al2O3-28PbF2-22CdF2-0.1TmF3 - xYbF3 - （4.9 - x） AlF3（x=0, 0.5, 1.0, 1.5, 2.0） in tool fraction, Furthermore, the upconversion luminescence c...Novel oxyfluoride glasses are developed with the composition of 30SiO2-15Al2O3-28PbF2-22CdF2-0.1TmF3 - xYbF3 - （4.9 - x） AlF3（x=0, 0.5, 1.0, 1.5, 2.0） in tool fraction, Furthermore, the upconversion luminescence characteristics under a 970nm excitation are investigated. Intense blue, red and near infrared luminescences peaked at 453nm, 476nm, 647nm and 789nm, which correspond to the transitions of Tm^3＋： ^1D2 →^3F4, ^1G4 →^3H6, ^1G4 →^3F4, and ^3H4 →^3H6, respectively, are observed. Due to the sensitization of Yb^3＋ ions, all the upconversion luminescence intensities are enhanced considerably with Yb^3＋ concentration increasing. The upconversion mechanisms are discussed based on the energy matching rule and quadratic dependence on excitation power. The results indicate that the dominant mechanism is the excited state absorption for those upconversion emissions.展开更多
The electronic structures and magnetic properties of the Cu and N codoped 3C-Si C system have been investigated by the first-principles calculation.The results show that the Cu doped Si C system prefers the anti-ferro...The electronic structures and magnetic properties of the Cu and N codoped 3C-Si C system have been investigated by the first-principles calculation.The results show that the Cu doped Si C system prefers the anti-ferromagnetic（AFM） state.Compared to the Cu doped system,the ionicities of C–Cu and C–Si in Cu and N codoped Si C are respectively enhanced and weakened.Especially,the Cu and N codoped Si C systems favor the ferromagnetic（FM） coupling.The FM interactions can be explained by virtual hopping.However,higher N concentration will weaken the ferromagnetism.In order to keep the FM interaction,the N concentration should be restricted within 9.3% according to our analysis.展开更多
NS codoped carbon nanorods（NS-CNRs） were prepared using crab shell as template and polyphenylene sulfide（PPS） as both the C and S precursor, followed by carbonization in NH_3. The as-obtained NS-CNRs had a diamete...NS codoped carbon nanorods（NS-CNRs） were prepared using crab shell as template and polyphenylene sulfide（PPS） as both the C and S precursor, followed by carbonization in NH_3. The as-obtained NS-CNRs had a diameter of ~50 nm, length of several micrometers, and N and S contents of 12.5 at.% and 3.7 at.%,respectively, which can serve as anodes for both lithium-ion batteries（LIBs） and sodium ion batteries（SIBs）. When serving as an anode of LIB, the NS-CNRs delivered gravimetric capacities of 2154 mAh g^（-1）at current densities of 0.1 A g^（-1）and 625 mAh g^（-1）at current densities of 5.0 A g^（-1）for 1000 cycles.When serving as an anode of SIB, the NS-CNRs delivered gravimetric capacities of 303 mAh g^（-1）at current densities of 0.1 A g^（-1）and 230 mAh g^（-1）at current densities of 1.0 A g^（-1）for 3000 cycles. The excellent electrochemical performance of NS-CNRs could be ascribed to the one-dimensional nanometer structure and high level of heteroatom doping. We expect that the obtained NS-CNRs would benefit for the future development of the doped carbon materials for lithium ion batteries and other extended applications such as supercapacitor, catalyst and hydrogen storage.展开更多
Adsorption is an effective and low-cost method for removing antibiotics and dyes. However, it remains a challenge to prepare an adsorbent with excellent adsorption properties for both various antibiotics and dyes. Her...Adsorption is an effective and low-cost method for removing antibiotics and dyes. However, it remains a challenge to prepare an adsorbent with excellent adsorption properties for both various antibiotics and dyes. Herein, Fe/Cr-codoped ZnO with high adsorption capacity and fast adsorption rate are prepared by an environmentally friendly solvothermal method. Fe/Cr-codope ZnO with a diameter of 10–20 nm exhibits superior adsorption capacities for the antibiotics of tetracycline hydrochloride(TC-HCl)(826.45 mg g-1) and tetracycline(TC)(331.01 mg g-1), and anionic dyes of methyl orange(MO)(1023.88 mg g-1), methyl blue(MB)(726.26 mg g-1) and direct red(DR)(642.25 mg g-1). Meanwhile, it presents fast adsorption rate, it only took 30 min to reach more than 90% of the equilibrium adsorption amount for TC-HCl, TC, MO, MB and DR. The adsorption process closely fitted the Langmuir isotherm model and pseudo second-order rate equation. More importantly, simple method has been developed for separating the pollutant from the adsorbent, which not only regenerates the materials, but also completes the recovery of antibiotics and dyes, avoiding the secondary pollution. The broad-spectrum, rapid, environment-friendly and effective adsorption properties make Fe/Crcodoped ZnO a promising adsorbent for water treatments.展开更多
The nonuniform Yb-Er Codoped Al2O3 films were prepared on SiO2/Si substrates using a medium frequency magnetron sputtering system. Two asymmetry targets in the system were introduced to realize the nonuniform dopant. ...The nonuniform Yb-Er Codoped Al2O3 films were prepared on SiO2/Si substrates using a medium frequency magnetron sputtering system. Two asymmetry targets in the system were introduced to realize the nonuniform dopant. Some curves of Photoluminescence （PL） peak intensity were obtained by adjusting the deposition parameters, such as, the pillar number of erbium and ytterbium in the mixed target and the distance between a sample table and targets. Typically, the curve of PL peak intensity against the offset distance was approximately linear. The ratio of the PL intensity at the two ends of the same sample was 12.6 and the slope was 71.83/mm when the pillar numbers of the erbium and ytterbium in the mixed target are 5 and 60, respectively, and the distance between targets and the sample table is 2.9 cm.展开更多
Nano-F-/Ce3+/TiO2 particles were prepared by hydrolysis of tetrabutyl titanate in a mixed CF3COOH-Ce(NO3)3-H2O solution. The photocatalytic decomposition of methylene blue in aqueous solution was used to evaluate thei...Nano-F-/Ce3+/TiO2 particles were prepared by hydrolysis of tetrabutyl titanate in a mixed CF3COOH-Ce(NO3)3-H2O solution. The photocatalytic decomposition of methylene blue in aqueous solution was used to evaluate their photocatalytic activities. The powders were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersion X-ray spectrum (EDS), and Brunauer-Emmett-Teller (BET) surface area analysis. The results showed that F- and Ce3+ were doped into TiO2. The appropriate content of fluorine and cerium were 2.0% and 1.0% (atom fraction) respectively. The codoped nano-F-/Ce3+/TiO2 particles had higher BET specific surface area, smaller crystallite size and higher photocatalytic activity than those of undoped TiO2 particles.展开更多
An efficient and compact double-pass optical fiber amplifier is demonstrated using a newly developed hafnia bismuth erbium co-doped fiber（HBEDF） as a gain medium. The HBEDF is fabricated using a modified chemical va...An efficient and compact double-pass optical fiber amplifier is demonstrated using a newly developed hafnia bismuth erbium co-doped fiber（HBEDF） as a gain medium. The HBEDF is fabricated using a modified chemical vapor deposition in conjunction with solution doping. The fiber has an erbium ion concentration of 12500 ppm.At the optimum length of 0.5 m, the HBEDF amplifier（HBEDFA） achieves a flat gain of 26 d B with a gain variation of less than 1.5 d B within a wavelength region from 1530 to 1560 nm when the input signal and pump power are fixed at-30 d Bm and 140 m W, respectively. On the other hand, at the input signal power of-10 d Bm,the HBEDFA also achieves a flat gain of 14.2 d B with a gain variation of less than 2.5 d B within a wide wavelength region from 1525 to 1570 nm. Compared with the conventional zirconia erbium co-doped fiber based amplifier,the proposed HBEDFA obtains a more efficient gain and lower noise figure. For an input signal of-30 d Bm, the gain improvements of 6.2 d B and 4.8 d B are obtained at 1525 nm and 1540 nm, respectively.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
First-principles plane-wave pseudopotential calculations are performed to study the geometrical structures, for- mation energies, and electronic and optical properties of Y-doped, N-doped, and （Y, N）-codoped Ti02. T...First-principles plane-wave pseudopotential calculations are performed to study the geometrical structures, for- mation energies, and electronic and optical properties of Y-doped, N-doped, and （Y, N）-codoped Ti02. The calculated results show that Y and N codoping leads to lattice distortion, easier separation of photogenerated electron-hole pairs and band gap narrowing. The optical absorption spectra indicate that an obvious red-shift occurs upon Y and N codoping, which enhances visible-light photocatalytic activity.展开更多
La3+ was selected to elevate the lattice electronic conductivity of LiFePO4,and LiFePO4/(C+La3+) cathode powders were synthesized by microwave heating using a domestic microwave oven for 35 min. The microstructures an...La3+ was selected to elevate the lattice electronic conductivity of LiFePO4,and LiFePO4/(C+La3+) cathode powders were synthesized by microwave heating using a domestic microwave oven for 35 min. The microstructures and morphologies of the synthesized materials were investigated by XRD and SEM. The electrochemical performances were evaluated by galvanostatic charge-discharge. The electrochemical performance of LiFePO4 with different La3+ contents was studied. Results indicated that the initial specific disch...展开更多
The crystal structures, electronic structures and optical properties of nitrogen or/and praseodymium doped anatase TiO2 were calculated by first principles with the plane-wave ultrasoft pseudopotential method based on...The crystal structures, electronic structures and optical properties of nitrogen or/and praseodymium doped anatase TiO2 were calculated by first principles with the plane-wave ultrasoft pseudopotential method based on density functional theory. Highly efficient visible-light-induced nitrogen or/and praseodymium doped anatase TiO2 nanocrystal photocatalyst were synthesized by a microwave chemical method. The calculated results show that the photocatalytic activity of TiO2 can be enhanced by N doping or Pr doping, and can be further enhanced by N＋Pr codoping. The band gap change of the codoping TiO2 is more obvious than that of the single ion doping, which results in the red shift of the optical absorption edges. The results are of great significance for the understanding and further development of visible-light response high activity modified TiO2 photocatalyst. The photocatalytic activity of the samples for methyl blue degradation was investigated under the irradiation of fluorescent light. The experimental results show that the codoping TiO2 photocatalytic activity is obviously higher than that of the single ion doping. The experimental results accord with the calculated results.展开更多
The performances of high power Er/Yb codoped fiber linear cavity lasers are investigated numerically. The numerical analysis is based on the iterative solution of rate equations for population density of the Er/Yb ion...The performances of high power Er/Yb codoped fiber linear cavity lasers are investigated numerically. The numerical analysis is based on the iterative solution of rate equations for population density of the Er/Yb ions. The behaviors of co-pump and counter-pump methods are contrasted. Dependence of output power on input pump power, output reflectivity, operating wavelength and active fiber length is simulated, respectively. High conversion efficiency Er/Yb laser output is obtained in simulations and experiments.展开更多
Mo-C codoped TiO2 films were prepared by RF magnetron cosputtering. Ultraviolet-visible spectroscopy, atomic force microscopy, X-ray photoelectron spectroscopy, energy dispersive X-ray Analysis and X-Ray Diffraction w...Mo-C codoped TiO2 films were prepared by RF magnetron cosputtering. Ultraviolet-visible spectroscopy, atomic force microscopy, X-ray photoelectron spectroscopy, energy dispersive X-ray Analysis and X-Ray Diffraction were used to study the influences of codoping on energy gap, surface morphology, valence states of elements, ions content and crystal structure, respectively. The concentration of photogenerated carriers was measured by studying photocurrent density, while catalytic property was evaluated by observing degradation rate of methylene blue under visible light. A Mo-doped TiO2 film, whose content of Mo had been optimized in advance, was prepared and later used for subsequent comparisons with codoped samples. The result indicates that Mo-C codoping could curtail the energy gap and shift the absorption edge toward visible range. Under the illumination of visible light, codoped TiO2 films give rise to stronger photocurrent due to smaller band gaps. It is also found that Mo, C codoping results in a porous surface, whose area declines gradually with increasing carbon content. Carbon and Molybdenum doses were delicately optimized. Under the illumination of visible light, sample doped with 9.78at% carbon and 0.36at% Mo presents the strongest photocurrent which is about 8 times larger than undoped TiO2 films, and about 6 times larger than samples doped with Mo only.展开更多
On the basis of the bond valence model, the preferential occupancy of various dopant such as Mn2+, Eu3+, Er3+, Nd3+, Lu3+, Yb3+, In3+, Cr3+, Fe3+ and Ti4+ in the ideal stoichiometric lithium niobate (SLN) crystallogra...On the basis of the bond valence model, the preferential occupancy of various dopant such as Mn2+, Eu3+, Er3+, Nd3+, Lu3+, Yb3+, In3+, Cr3+, Fe3+ and Ti4+ in the ideal stoichiometric lithium niobate (SLN) crystallographic frame was investigated in a viewpoint of chemical bonds. Theoretical analysis indicates that the dopant occupancy is significantly influenced by the anti-site Nb4+Li. Our work also shows that Mg-like ions (Mg2+, Zn2+, In3+, Sc3+) have a repulsive effect on Nb4+Li ions. When removing Nb4+Li ion by codoping Mg-like ions, the dopant occupancy in the LN crystallographic frame is determined by the natural characteristics of dopant, which is consistent well with the result in the ideal SLN crystals.展开更多
Adsorbents with simple preparation and high surface area have become increasingly prevalent for the removal of organic contaminants.Herein,a carbon nanoplate codoped by Co and N elements with abundant ordered mesoporo...Adsorbents with simple preparation and high surface area have become increasingly prevalent for the removal of organic contaminants.Herein,a carbon nanoplate codoped by Co and N elements with abundant ordered mesoporous(Co/N-MCs)was applied as an adsorbent for tetracycline removal.Taking integrated advantages of ordered mesopores on carbon-based structures and N-doping inducing the strengthenedπ–πdispersion and generation of pyridinic N,as well as cobaltic nanoparticles embedded in carbon nanoplates,the Co/N-MCs was tailored for high efficiently absorbing tetracycline viaπ-πinteraction,Lewis acid-base interaction,metal complexation and electrostatic attraction.The Co/N-MCs had the advantages of high surface area,porous structure,plenty adsorption sites,and easy separation.As such,the as-prepared Co/N-MCs adsorbents significantly enhanced tetracycline removal performance with a maximum adsorption capacity of 344.83 mg·g^(-1) at pH 6 and good reusability,which was finally applied to removal tetracycline from tap water sample.Furthermore,the adsorption process towards tetracycline hydrochloride could be well attributed to the pseudo-second-order kinetic and Langmuir isotherm models.Compared with traditional carbon-based adsorbents,it owns a simpler synthesis method and a higher adsorption capacity,as well as it is a promising candidate for water purification.展开更多
Zn-Cu-codoped SnO2 nanoparticles have been synthesized by chemical precipitation method. All nanoparticles are crystalline, with the average size increases from 2.55 nm to 4.13 nm as the calcination temperature increa...Zn-Cu-codoped SnO2 nanoparticles have been synthesized by chemical precipitation method. All nanoparticles are crystalline, with the average size increases from 2.55 nm to 4.13 nm as the calcination temperature increases from 400℃ to 600℃. The high calcination temperature can enhance the crystalline quality and grain growth. The oxygen content decreases with decreasing calcination temperature; at a low temperature of 400℃, Zn-Cu-codoped SnO2 nanoparticles are in a rather oxygen-poor state having many oxygen vacancies. The optical band gap energies of Zn-Cu-codoped SnO2 nanoparticles calcined at 400℃ and 600℃ are decreased from 3.93 eV to 3.62 eV due to quantum confinement effects. Both samples exhibit room-temperature ferromagnetism, with a larger saturation magnetization at 400℃ due to the presence of large density of defects such as oxygen vacancies. Zn-Cu-codoped SnO2 nanoparticles exhibit large optical band gap energies and room temperature ferromagnetism, which make them potential candidates for applications in optoelectronics and spintronics.展开更多
基金supported by the National Natural Science Foundation of China (31890771 and 31901249)the Young Elite Scientists Sponsorship Program by CAST (2019QNRC001)+3 种基金the Hunan Provincial Technical Innovation Platform and Talent Program in Science and Technology (2020RC3041)the Training Program for Excellent Young Innovators of Changsha (kq2106056)the Hunan Provincial Natural Science Foundation of China (2022JJ30079)the Postgraduate Technology Innovation Project of Central South University of Forestry and Technology (2022CX02017)。
文摘Carbon materials are effective substitutes for Pt counter electrodes(CEs) in dye-sensitized solar cells(DSSCs). However, many of these materials, such as carbon nanotubes and graphene, are expensive and require complex preparation process. Herein, waste lignin, recycled from hazardous black liquors,is used to create oxygen-nitrogen-sulfur codoped carbon microspheres for use in DSSC CEs through the facile process of low-temperature preoxidation and high-temperature self-activation. The large number of ester bonds formed by preoxidation increase the degree of cross-linking of the lignin chains, leading to the formation of highly disordered carbon with ample defect sites during pyrolysis. The presence of organic O/N/S components in the waste lignin results in high O/N/S doping of the pyrolysed carbon,which increases the electrolyte ion adsorption and accelerates the electron transfer at the CE/electrolyte interface, as confirmed by density functional theory(DFT) calculations. The presence of inorganic impurities enables the construction of a hierarchical micropore-rich carbon structure through the etching effect during self-activation, which can provide abundant catalytically active sites for the reversible adsorption/desorption of electrolyte ions. Under these synergistic effects, the DSSCs that use this novel carbon CE achieve a quite high power-conversion efficiency of 9.22%. To the best of our knowledge, the value is a new record reported so far for biomass-carbon-based DSSCs.
基金This work was supported by the National Natural Sci- ence Foundation of China （No.11034006, No.21273208, and No.21473168）, the Anhui Provincial Natural Sci- ence Foundation （No.1408085QB26）, the hmdamental Research Funds for the Central Universities, the China Postdoctoral Science Foundation （No.2012M511409）, and the Supercomputing Center of Chinese Academy of Sciences, Shanghai and USTC Supercomputer Cen- ters.
文摘Doping with various impurities is an effective approach to improve the photoelectrochemical properties of TiO2. Here, we explore the effect of oxygen vacancy on geometric and elec- tronic properties of compensated （i.e. V-N and Cr-C） and non-compensated （i.e. V-C and Cr-N） codoped anatase TiO2 by performing extensive density functional theory calculations. Theoretical results show that oxygen vacancy prefers to the neighboring site of metal dopant （i.e. V or Cr atom）. After introduction of oxygen vacancy, the unoccupied impurity bands located within band gap of these codoped TiO2 will be filled with electrons, and the posi- tion of conduction band offset does not change obviously, which result in the reduction of photoinduced carrier recombination and the good performance for hydrogen production via water splitting. Moreover, we find that oxygen vacancy is easily introduced in V-N codoped TiO2 under O-poor condition. These theoretical insights are helpful for designing codoped TiO2 with high photoelectrochemical performance.
基金financial support of the National Natural Science Foundation of China (Grant No. 21263016, 21363015, 51662029, 21863006)the Youth Science Foundation of Jiangxi Province (Grant No. 20192BAB216001)the Key Laboratory of Jiangxi Province for Environment and Energy Catalysis (20181BCD40004)。
文摘Carbon materials have shown remarkable usefulness in facilitating the performance of insulating sulfur cathode for lithium–sulfur batteries owing to their excellent conductivity and porous structure. However,the anxiety is the poor affinity toward polar polysulfides due to the intrinsic nonpolar surface of carbon.Herein, we report a direct pyrolysis of the mixture urea and boric acid to synthesize B/N–codoped hierarchically porous carbon nanosheets(B–N–CSs) as efficient sulfur host for lithium–sulfur battery. The graphene–like B–N–CSs provides high specific surface area and porous structure with abundant micropores(1.1 nm) and low–range mesopores(2.3 nm), thereby constraining the sulfur active materials within the pores. More importantly, the codoped B/N elements can further enhance the polysulfide confinement through strong Li–N and B–S interaction based on the Lewis acid–base theory. These structural superiorities significantly suppress the shuttle effect by both physical confinement and chemical interaction, and promote the redox kinetics of polysulfide conversion. When evaluated as the cathode host, the S/B–N–CSs composite displays the excellent performance with a high reversible capacity up to 772 m A h g–1 at 0.5 C and a low fading rate of ^0.09% per cycle averaged upon 500 cycles. In particular, remarkable stability with a high capacity retention of 87.1% can be realized when augmenting the sulfur loading in the cathode up to 4.6 mg cm^(-2).
基金Project supported by the Shanghai ＂Post-Qi-Ming-Xing plan＂ for Young Scientists, China （Grant No 04QMX1448） and the National Natural Science Foundation of China （Grant No 60207006）.The author would like to thank Wen L,Shen Y H and Zhao Y for their help in machining and measuring.
文摘Novel oxyfluoride glasses are developed with the composition of 30SiO2-15Al2O3-28PbF2-22CdF2-0.1TmF3 - xYbF3 - （4.9 - x） AlF3（x=0, 0.5, 1.0, 1.5, 2.0） in tool fraction, Furthermore, the upconversion luminescence characteristics under a 970nm excitation are investigated. Intense blue, red and near infrared luminescences peaked at 453nm, 476nm, 647nm and 789nm, which correspond to the transitions of Tm^3＋： ^1D2 →^3F4, ^1G4 →^3H6, ^1G4 →^3F4, and ^3H4 →^3H6, respectively, are observed. Due to the sensitization of Yb^3＋ ions, all the upconversion luminescence intensities are enhanced considerably with Yb^3＋ concentration increasing. The upconversion mechanisms are discussed based on the energy matching rule and quadratic dependence on excitation power. The results indicate that the dominant mechanism is the excited state absorption for those upconversion emissions.
基金Project supported by the Higher School Science Research Outstanding Youth Fund Project of Ningxia,China(Grant No.NGY2015049)
文摘The electronic structures and magnetic properties of the Cu and N codoped 3C-Si C system have been investigated by the first-principles calculation.The results show that the Cu doped Si C system prefers the anti-ferromagnetic（AFM） state.Compared to the Cu doped system,the ionicities of C–Cu and C–Si in Cu and N codoped Si C are respectively enhanced and weakened.Especially,the Cu and N codoped Si C systems favor the ferromagnetic（FM） coupling.The FM interactions can be explained by virtual hopping.However,higher N concentration will weaken the ferromagnetism.In order to keep the FM interaction,the N concentration should be restricted within 9.3% according to our analysis.
基金the National Key Basic Research Program of China (2015CB351903)the National Natural Science Foundation of China (51402282, 51373160,21474095, 21476104, 21373197)+1 种基金the Fundamental Research Funds for the Central Universities (WK3430000003)the 100 Talents Program of the Chinese Academy of Sciences
文摘NS codoped carbon nanorods（NS-CNRs） were prepared using crab shell as template and polyphenylene sulfide（PPS） as both the C and S precursor, followed by carbonization in NH_3. The as-obtained NS-CNRs had a diameter of ~50 nm, length of several micrometers, and N and S contents of 12.5 at.% and 3.7 at.%,respectively, which can serve as anodes for both lithium-ion batteries（LIBs） and sodium ion batteries（SIBs）. When serving as an anode of LIB, the NS-CNRs delivered gravimetric capacities of 2154 mAh g^（-1）at current densities of 0.1 A g^（-1）and 625 mAh g^（-1）at current densities of 5.0 A g^（-1）for 1000 cycles.When serving as an anode of SIB, the NS-CNRs delivered gravimetric capacities of 303 mAh g^（-1）at current densities of 0.1 A g^（-1）and 230 mAh g^（-1）at current densities of 1.0 A g^（-1）for 3000 cycles. The excellent electrochemical performance of NS-CNRs could be ascribed to the one-dimensional nanometer structure and high level of heteroatom doping. We expect that the obtained NS-CNRs would benefit for the future development of the doped carbon materials for lithium ion batteries and other extended applications such as supercapacitor, catalyst and hydrogen storage.
基金supported by the National Natural Science Foundation of China (Nos. 51672144, 51572137, 51702181)the Natural Science Foundation of Shandong Province (Nos. ZR2017BB013, ZR2019BEM042)+2 种基金the Higher Educational Science and Technology Program of Shandong Province (Nos. J17KA014, J18KA001, J18KA033)the Taishan Scholars Program of Shandong Province (No. ts201511034)the Overseas Taishan Scholars Program。
文摘Adsorption is an effective and low-cost method for removing antibiotics and dyes. However, it remains a challenge to prepare an adsorbent with excellent adsorption properties for both various antibiotics and dyes. Herein, Fe/Cr-codoped ZnO with high adsorption capacity and fast adsorption rate are prepared by an environmentally friendly solvothermal method. Fe/Cr-codope ZnO with a diameter of 10–20 nm exhibits superior adsorption capacities for the antibiotics of tetracycline hydrochloride(TC-HCl)(826.45 mg g-1) and tetracycline(TC)(331.01 mg g-1), and anionic dyes of methyl orange(MO)(1023.88 mg g-1), methyl blue(MB)(726.26 mg g-1) and direct red(DR)(642.25 mg g-1). Meanwhile, it presents fast adsorption rate, it only took 30 min to reach more than 90% of the equilibrium adsorption amount for TC-HCl, TC, MO, MB and DR. The adsorption process closely fitted the Langmuir isotherm model and pseudo second-order rate equation. More importantly, simple method has been developed for separating the pollutant from the adsorbent, which not only regenerates the materials, but also completes the recovery of antibiotics and dyes, avoiding the secondary pollution. The broad-spectrum, rapid, environment-friendly and effective adsorption properties make Fe/Crcodoped ZnO a promising adsorbent for water treatments.
基金Project supported by the National Natural Science Foundation of China (60477023)the Natural Science Foundation of Science and Tech-nology Commission of Liaoning Province (20062137)
文摘The nonuniform Yb-Er Codoped Al2O3 films were prepared on SiO2/Si substrates using a medium frequency magnetron sputtering system. Two asymmetry targets in the system were introduced to realize the nonuniform dopant. Some curves of Photoluminescence （PL） peak intensity were obtained by adjusting the deposition parameters, such as, the pillar number of erbium and ytterbium in the mixed target and the distance between a sample table and targets. Typically, the curve of PL peak intensity against the offset distance was approximately linear. The ratio of the PL intensity at the two ends of the same sample was 12.6 and the slope was 71.83/mm when the pillar numbers of the erbium and ytterbium in the mixed target are 5 and 60, respectively, and the distance between targets and the sample table is 2.9 cm.
基金the Natural Science Foundation of Hebei Province (203364)the Natural Science Foundation of Hebei University of Science and Technology (XL2006038)
文摘Nano-F-/Ce3+/TiO2 particles were prepared by hydrolysis of tetrabutyl titanate in a mixed CF3COOH-Ce(NO3)3-H2O solution. The photocatalytic decomposition of methylene blue in aqueous solution was used to evaluate their photocatalytic activities. The powders were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersion X-ray spectrum (EDS), and Brunauer-Emmett-Teller (BET) surface area analysis. The results showed that F- and Ce3+ were doped into TiO2. The appropriate content of fluorine and cerium were 2.0% and 1.0% (atom fraction) respectively. The codoped nano-F-/Ce3+/TiO2 particles had higher BET specific surface area, smaller crystallite size and higher photocatalytic activity than those of undoped TiO2 particles.
文摘An efficient and compact double-pass optical fiber amplifier is demonstrated using a newly developed hafnia bismuth erbium co-doped fiber（HBEDF） as a gain medium. The HBEDF is fabricated using a modified chemical vapor deposition in conjunction with solution doping. The fiber has an erbium ion concentration of 12500 ppm.At the optimum length of 0.5 m, the HBEDF amplifier（HBEDFA） achieves a flat gain of 26 d B with a gain variation of less than 1.5 d B within a wavelength region from 1530 to 1560 nm when the input signal and pump power are fixed at-30 d Bm and 140 m W, respectively. On the other hand, at the input signal power of-10 d Bm,the HBEDFA also achieves a flat gain of 14.2 d B with a gain variation of less than 2.5 d B within a wide wavelength region from 1525 to 1570 nm. Compared with the conventional zirconia erbium co-doped fiber based amplifier,the proposed HBEDFA obtains a more efficient gain and lower noise figure. For an input signal of-30 d Bm, the gain improvements of 6.2 d B and 4.8 d B are obtained at 1525 nm and 1540 nm, respectively.
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Project supported by the National Natural Science Foundation of China (Grant Nos. 10647008, 50971099, and 21176199)the Research Fund for the Doctoral Program of Higher Education, China (Grant Nos. 20096101110017 and 20096101110013)+1 种基金the Key Project of the Natural Science Foundation of Shaanxi Province, China (Grant Nos. 2010JZ002 and 2011JM1001)the Graduate Innovation Fund of Northwest University, China (Grant No. 10YZZ38)
文摘First-principles plane-wave pseudopotential calculations are performed to study the geometrical structures, for- mation energies, and electronic and optical properties of Y-doped, N-doped, and （Y, N）-codoped Ti02. The calculated results show that Y and N codoping leads to lattice distortion, easier separation of photogenerated electron-hole pairs and band gap narrowing. The optical absorption spectra indicate that an obvious red-shift occurs upon Y and N codoping, which enhances visible-light photocatalytic activity.
基金the National Natural Science Foundation of China (No. 50872090)
文摘La3+ was selected to elevate the lattice electronic conductivity of LiFePO4,and LiFePO4/(C+La3+) cathode powders were synthesized by microwave heating using a domestic microwave oven for 35 min. The microstructures and morphologies of the synthesized materials were investigated by XRD and SEM. The electrochemical performances were evaluated by galvanostatic charge-discharge. The electrochemical performance of LiFePO4 with different La3+ contents was studied. Results indicated that the initial specific disch...
基金Project supported by the National Natural Science Foundation of China(Grant No.50862009)the New Century Excellent Talents in University of the Ministry of Education,China(Grant No.NCET-04-0915)the Natural Science Foundation of Yunnan Province of China(Grant No.2005E007M)
文摘The crystal structures, electronic structures and optical properties of nitrogen or/and praseodymium doped anatase TiO2 were calculated by first principles with the plane-wave ultrasoft pseudopotential method based on density functional theory. Highly efficient visible-light-induced nitrogen or/and praseodymium doped anatase TiO2 nanocrystal photocatalyst were synthesized by a microwave chemical method. The calculated results show that the photocatalytic activity of TiO2 can be enhanced by N doping or Pr doping, and can be further enhanced by N＋Pr codoping. The band gap change of the codoping TiO2 is more obvious than that of the single ion doping, which results in the red shift of the optical absorption edges. The results are of great significance for the understanding and further development of visible-light response high activity modified TiO2 photocatalyst. The photocatalytic activity of the samples for methyl blue degradation was investigated under the irradiation of fluorescent light. The experimental results show that the codoping TiO2 photocatalytic activity is obviously higher than that of the single ion doping. The experimental results accord with the calculated results.
基金National Natural Science Foundation of China ( 60137010 ) Tianjin Key Project Foundation of China(033183611)
文摘The performances of high power Er/Yb codoped fiber linear cavity lasers are investigated numerically. The numerical analysis is based on the iterative solution of rate equations for population density of the Er/Yb ions. The behaviors of co-pump and counter-pump methods are contrasted. Dependence of output power on input pump power, output reflectivity, operating wavelength and active fiber length is simulated, respectively. High conversion efficiency Er/Yb laser output is obtained in simulations and experiments.
基金Funded by Chinese National Key Scientific Projects(No.2012CB934303)the Guizhou Education Foundation(KY[2015]332)
文摘Mo-C codoped TiO2 films were prepared by RF magnetron cosputtering. Ultraviolet-visible spectroscopy, atomic force microscopy, X-ray photoelectron spectroscopy, energy dispersive X-ray Analysis and X-Ray Diffraction were used to study the influences of codoping on energy gap, surface morphology, valence states of elements, ions content and crystal structure, respectively. The concentration of photogenerated carriers was measured by studying photocurrent density, while catalytic property was evaluated by observing degradation rate of methylene blue under visible light. A Mo-doped TiO2 film, whose content of Mo had been optimized in advance, was prepared and later used for subsequent comparisons with codoped samples. The result indicates that Mo-C codoping could curtail the energy gap and shift the absorption edge toward visible range. Under the illumination of visible light, codoped TiO2 films give rise to stronger photocurrent due to smaller band gaps. It is also found that Mo, C codoping results in a porous surface, whose area declines gradually with increasing carbon content. Carbon and Molybdenum doses were delicately optimized. Under the illumination of visible light, sample doped with 9.78at% carbon and 0.36at% Mo presents the strongest photocurrent which is about 8 times larger than undoped TiO2 films, and about 6 times larger than samples doped with Mo only.
基金Project supported by the National Natural Science Foundation of China (20471012), Foundation for the Author of National Excellent Doctoral Dissertation of China (200322), the Research Fund for the Doctoral Program of Higher Education (20040141004) and the Scientific Research Foundation for the Returned Overseas Chinese Scholars, State Education Ministry
文摘On the basis of the bond valence model, the preferential occupancy of various dopant such as Mn2+, Eu3+, Er3+, Nd3+, Lu3+, Yb3+, In3+, Cr3+, Fe3+ and Ti4+ in the ideal stoichiometric lithium niobate (SLN) crystallographic frame was investigated in a viewpoint of chemical bonds. Theoretical analysis indicates that the dopant occupancy is significantly influenced by the anti-site Nb4+Li. Our work also shows that Mg-like ions (Mg2+, Zn2+, In3+, Sc3+) have a repulsive effect on Nb4+Li ions. When removing Nb4+Li ion by codoping Mg-like ions, the dopant occupancy in the LN crystallographic frame is determined by the natural characteristics of dopant, which is consistent well with the result in the ideal SLN crystals.
基金financed by Grants from National Science Foundation of China(21675127,31901794)Chinese Universities Scientific Fund(2452018083)+3 种基金the National Postdoctoral Program for Innovative Talents(BX20180263)the Tang Scholar by Cyrus Tang Foundation,the Young Talent Fund of University Association for Science and Technology in Shaanxi,China(2019-02-03)the Development Project of Qinghai Provincial Key Laboratory(2017-ZJY10)the Key Research and Development Program of Shaanxi Province(2019NY-111)。
文摘Adsorbents with simple preparation and high surface area have become increasingly prevalent for the removal of organic contaminants.Herein,a carbon nanoplate codoped by Co and N elements with abundant ordered mesoporous(Co/N-MCs)was applied as an adsorbent for tetracycline removal.Taking integrated advantages of ordered mesopores on carbon-based structures and N-doping inducing the strengthenedπ–πdispersion and generation of pyridinic N,as well as cobaltic nanoparticles embedded in carbon nanoplates,the Co/N-MCs was tailored for high efficiently absorbing tetracycline viaπ-πinteraction,Lewis acid-base interaction,metal complexation and electrostatic attraction.The Co/N-MCs had the advantages of high surface area,porous structure,plenty adsorption sites,and easy separation.As such,the as-prepared Co/N-MCs adsorbents significantly enhanced tetracycline removal performance with a maximum adsorption capacity of 344.83 mg·g^(-1) at pH 6 and good reusability,which was finally applied to removal tetracycline from tap water sample.Furthermore,the adsorption process towards tetracycline hydrochloride could be well attributed to the pseudo-second-order kinetic and Langmuir isotherm models.Compared with traditional carbon-based adsorbents,it owns a simpler synthesis method and a higher adsorption capacity,as well as it is a promising candidate for water purification.
基金Project supported by the Natural Science Foundation of Zhejiang Province,China(Grant No.LR16F040001)
文摘Zn-Cu-codoped SnO2 nanoparticles have been synthesized by chemical precipitation method. All nanoparticles are crystalline, with the average size increases from 2.55 nm to 4.13 nm as the calcination temperature increases from 400℃ to 600℃. The high calcination temperature can enhance the crystalline quality and grain growth. The oxygen content decreases with decreasing calcination temperature; at a low temperature of 400℃, Zn-Cu-codoped SnO2 nanoparticles are in a rather oxygen-poor state having many oxygen vacancies. The optical band gap energies of Zn-Cu-codoped SnO2 nanoparticles calcined at 400℃ and 600℃ are decreased from 3.93 eV to 3.62 eV due to quantum confinement effects. Both samples exhibit room-temperature ferromagnetism, with a larger saturation magnetization at 400℃ due to the presence of large density of defects such as oxygen vacancies. Zn-Cu-codoped SnO2 nanoparticles exhibit large optical band gap energies and room temperature ferromagnetism, which make them potential candidates for applications in optoelectronics and spintronics.
