As a catalyst of the air cathode in zinc-air batteries,tungstic acid ferrous(FeWO_(4)),a nanoscale transition metal tungstate,shows a broad application prospect in the oxygen reduction reaction(ORR).While FeWO_(4)poss...As a catalyst of the air cathode in zinc-air batteries,tungstic acid ferrous(FeWO_(4)),a nanoscale transition metal tungstate,shows a broad application prospect in the oxygen reduction reaction(ORR).While FeWO_(4)possesses favorable electrochemical properties and thermodynamic stability,its intrinsic semiconductor characteristics result in a relatively slow electron transfer rate,limiting the ORR catalytic activity.In this work,the electronic structure of FeWO_(4)is significantly modulated by introducing phosphorus(P)atoms with abundant valence electrons.The P doping can adjust the electronic structure of FeWO_(4)and then optimize oxygen-containing intermediates'absorption/desorption efficiency to achieve improved ORR activity.Furthermore,the sodium chloride template is utilized to construct a porous carbon framework for anchoring phosphorus-doped iron tungstate(P-FeWO_(4)/PNC).The porous carbon skeleton provides numerous active sites for the absorption/desorption and redox reactions on the P-FeWO_(4)/PNC surface and serves as mass transport channels for reactants and intermediates.The P-FeWO_(4)/PNC demonstrates ORR performance(E1/2=0.86 V vs.RHE).Furthermore,the zinc-air batteries incorporating the P-FeWO_(4)/PNC composite demonstrate an increased peak power density(172.2 mW·cm^(-2)),high specific capacity(810.1 mAh·g^(-1)),and sustained long-term cycling stability lasting up to 240 h.This research not only contributes to the advancement of cost-effective tungsten-based non-precious metallic ORR catalysts,but also guides their utilization in zinc-air batteries.展开更多
Mn^(2+)-doped CsPbCl_(3)(Mn^(2+):CsPbCl_(3)) nanocrystals(NCs) have attracted considerable attention due to their unique strong and broad orange-red emission band,presenting promising applications in the field of phot...Mn^(2+)-doped CsPbCl_(3)(Mn^(2+):CsPbCl_(3)) nanocrystals(NCs) have attracted considerable attention due to their unique strong and broad orange-red emission band,presenting promising applications in the field of photoelectric devices.However,pristine Mn^(2+):CsPbCl_(3)NCs commonly suffer from low photoluminescence quantum yield(PL QY) and stability issues.Herein,we introduced europium ions(Eu^(3+))into Mn^(2+):CsPbCl_(3)NCs via the thermal injection synthesis method to obtain high performance Eu^(3+)and Mn^(2+)codoped CsPbCl_(3)(Eu^(3+)/Mn^(2+):CsPbCl_(3)) NCs.The maximum PL QY of the resulting Eu^(3+)/Mn^(2+):CsPbCl_(3)NCs reaches up to 90.92%.It is found that the doping of Eu^(3+)ions significantly reduces the non-radiative recombination caused by high defect states,and improves the energy transfer efficiency from exciton to Mn^(2+),thereby boosting the PL performance.Moreover,doping Eu^(3+)ions notably improves the UV-light and water stability of Mn^(2+):CsPbCl_(3)NCs.We further demonstrate the application versatility of Eu^(3+)/Mn^(2+):CsPbCl_(3)NCs in white light emitting diodes(WLEDs) and optical anticounterfeiting applications.This work provides a valuable perspective for the attainment of high performance Mn^(2+):CsPbCl_(3)NCs and lays a foundation for the codoping of other lanthanide ions to adjust the luminescence properties of Mn^(2+):CsPbCl_(3)NCs.展开更多
The outstanding performance of O3-type NaNi_(1/3)Fe_(1/3)Mn_(1/3)O_(2)(NFM111)at both high and low temperatures coupled with its impressive specific capacity makes it an excellent cathode material for sodium-ion batte...The outstanding performance of O3-type NaNi_(1/3)Fe_(1/3)Mn_(1/3)O_(2)(NFM111)at both high and low temperatures coupled with its impressive specific capacity makes it an excellent cathode material for sodium-ion batteries.However,its poor cycling,owing to highpressure phase transitions,is one of its disadvantages.In this study,Cu/Ti was introduced into NFM111 cathode material using a solidphase method.Through both theoretically and experimentally,this study found that Cu doping provides a higher redox potential in NFM111,improving its reversible capacity and charge compensation process.The introduction of Ti would enhance the cycling stability of the material,smooth its charge and discharge curves,and suppress its high-voltage phase transitions.Accordingly,the NaNi_(0.27)Fe_(0.28)Mn_(0.33)Cu_(0.05)Ti_(0.06)O_(2)sample used in the study exhibited a remarkable rate performance of 142.97 mAh·g^(-1)at 0.1 C(2.0-4.2 V)and an excellent capacity retention of 72.81%after 300 cycles at 1C(1C=150 mA·g^(-1)).展开更多
This study focused on improving the cathode performance of Ba_(0.6)Sr_(0.4)Co_(0.85)Nb_(0.15)O_(3-δ)(BSCN)-based perovskite materials through molybdenum(Mo)doping.Pure BSCN and Mo-modified-BSCN—Ea_(0.6)Sr_(0.4)Co_(0...This study focused on improving the cathode performance of Ba_(0.6)Sr_(0.4)Co_(0.85)Nb_(0.15)O_(3-δ)(BSCN)-based perovskite materials through molybdenum(Mo)doping.Pure BSCN and Mo-modified-BSCN—Ea_(0.6)Sr_(0.4)Co_(0.85)Nb_(0.1)Mo_(0.05)O_(3-δ)(B S CNM_(0.05)),Ba_(0.6)Sr_(0.4)Co_(0.85)Nb_(0.05)Mo_(0.1)O_(3-δ)(BSCNM_(0.1)),and Ba_(0.6)Sr_(0.4)Co_(0.85)Mo_(0.15)O_(3-δ)(BSCM)—with Mo doping contents of 5mol%,10mol%,and15mol%,respectively,were successfully prepared using the sol-gel method.The effects of Mo doping on the crystal structure,conductivity,thermal expansion coefficient,oxygen reduction reaction(ORR)activity,and electrochemical performance were systematically evaluated using X-ray diffraction analysis,thermally induced characterization,electrochemical impedance spectroscopy,and single-cell performance tests.The results revealed that Mo doping could improve the conductivity of the materials,suppress their thermal expansion effects,and significantly improve the electrochemical performance.Surface chemical state analysis using X-ray photoelectron spectroscopy revealed that 5mol%Mo doping could facilitate a high adsorbed oxygen concentration leading to enhanced ORR activity in the materials.Density functional theory calculations confirmed that Mo doping promoted the ORR activity in the materials.At an operating temperature of 600℃,the BSCNM_(0.05)cathode material exhibited significantly enhanced electrochemical impedance characteristics,with a reduced area specific resistance of 0.048Ω·cm~2,which was lower than that of the undoped BSCN matrix material by 32.39%.At the same operating temperature,an anode-supported single cell using a BSCNM_(0.05)cathode achieved a peak power density of 1477 mW·cm^(-2),which was 30.71%,56.30%,and 171.50%higher than those of BSCN,BSCNM_(0.1),and B SCM,respectively.The improved ORR activity and electrochemical performance of BSCNM_(0.05)indicate that it can be used as a cathode material in low-temperature solid oxide fuel cells.展开更多
Sol--gol method was employed to synthesize Mg doped ZnO films on Si substrates. The annealing temperature-dependent structure and optical property of the produced samples were studied. An interesting result observed i...Sol--gol method was employed to synthesize Mg doped ZnO films on Si substrates. The annealing temperature-dependent structure and optical property of the produced samples were studied. An interesting result observed is that increasing Mg concentration in the studied samples induces the full width at half maximum （FWHM） of their near-band-edge （NBE） emission decrease and the defect related emission of the corresponding sample suppresses drastically. The possible mechanism of the observed result is discussed.展开更多
Nitrogen-doped single-walled carbon nanotubes （CNx-SWNTs） with tunable dopant concentrations were synthesized by chemical vapor deposition （CVD）, and their structure and elemental composition were characterized by...Nitrogen-doped single-walled carbon nanotubes （CNx-SWNTs） with tunable dopant concentrations were synthesized by chemical vapor deposition （CVD）, and their structure and elemental composition were characterized by using transmission electron microscopy （TEM） in combination with electron energy loss spectroscopy （EELS）. By comparing the Raman spectra of pristine and doped nanotubes, we observed the doping-induced Raman G band phonon stiffening and 2D band phonon softening, both of which reflect doping-induced renormalization of the electron and phonon energies in the nan- otubes and behave as expected in accord with the n-type doping effect. On the basis of first principles calculations of the distribution of delocalized carrier density in both the pristine and doped nanotubes, we show how the n-type doping occurs when nitrogen heteroatoms are substitutionally incorporated into the honeycomb tube-shell carbon lattice.展开更多
Na＋doped WO3 nanowire photocatalysts were prepared by using post-treatment（surface doping） and in situ（bulk doping） doping methods. Photocatalytic degradation of Methyl Blue was tested under visible light irradia...Na＋doped WO3 nanowire photocatalysts were prepared by using post-treatment（surface doping） and in situ（bulk doping） doping methods. Photocatalytic degradation of Methyl Blue was tested under visible light irradiation, the results showed that 1 wt.% Na＋bulk-doped WO3 performed better, with higher photoactivity than surface-doped WO3. Photoelectrochemical characterization revealed the differences in the photocatalytic process for surface doping and bulk doping. Uniform bulk doping could generate more electron–hole pairs, while minimizing the chance of electron–hole recombination. Some bulk properties such as the bandgap, Fermi level and band position could also be adjusted by bulk doping, but not by surface doping.展开更多
Monometallic doping has proved its superiority in improving either permselectivity or H_(2) permeability of organosilica membranes for H_(2)/CO_(2) separation,but it is still challenging to break the trade-off effect....Monometallic doping has proved its superiority in improving either permselectivity or H_(2) permeability of organosilica membranes for H_(2)/CO_(2) separation,but it is still challenging to break the trade-off effect.Herein,we report a series of Pd-Nb bimetallic doped 1,2-bis(triethoxysilyl)ethane(Pd-Nb-BTESE,PNB)membranes with different metal doping routes for simultaneously improving H_(2) permeance and H_(2)/CO_(2) permselectivity by the synergetic effects of Pd and Nb.The doped Pd can exist in the BTESE network as nanoparticles while the doped Nb is incorporated into BTESE network forming Nb-O-Si covalent bonds.The metal doping routes significantly influence the microstructure of PNB networks and gas separation performance of the PNB membranes.We found that the PNB membrane with Pd doping priority(PNB-Pd)exhibited the highest surface area and pore volume,comparing with Nb doping priority(PNB-Nb)or Pd-Nb simultaneous doping(PNB-PdNb).The PNB-Pd membrane could not only exhibit an excellent H_(2) permeance of~10^(−6) mol·m^(−2)·s^(−1)·Pa^(−1) but also a high H_(2)/CO_(2) permselectivity of 17.2.Our findings may provide novel insights into preparation of bimetallic doped organosilica membranes with excellent H_(2)/CO_(2) separation performance.展开更多
Due to their superior fluorescence,phosphorescence,and catalytic capabilities,carbon dots(CDs),an emerging class of fluorescent carbon nanomaterials,have a wide range of potential applications.The properties of CDs ha...Due to their superior fluorescence,phosphorescence,and catalytic capabilities,carbon dots(CDs),an emerging class of fluorescent carbon nanomaterials,have a wide range of potential applications.The properties of CDs have recently been controlled extensively by heteroatom doping.Boron atoms have been effectively doped into the structure of CDs due to their similar size to carbon atoms and excellent electron-absorbing ability to further improve the performance of CDs.In this review,we summarize the research progress of boron-doped CDs in recent years from the aspects of doping strategies,effects of boron doping on different performances of CDs and applications.Starting from the two aspects of single boron doping and boron and other atom co-doping,from different precursor materials to different synthesis methods,the doping strategies of boron-doped CDs are reviewed in detail.Then,the effects of boron doping on the fluorescence,phosphorescence and catalytic performance of CDs and applications of boron-doped CDs in optical sensors,information encryption and anti-counterfeiting are discussed.Finally,we further provide a prospect towards the future development of boron-doped CDs.展开更多
Zinc ion capacitors(ZICs)have drawn increas-ing interest in energy storage devices because of their economic benefits,high safety,and long cycling life.Nevertheless,the lack of high-performance cathodes for ZICs remai...Zinc ion capacitors(ZICs)have drawn increas-ing interest in energy storage devices because of their economic benefits,high safety,and long cycling life.Nevertheless,the lack of high-performance cathodes for ZICs remains a key challenge.Here,we fabricated B,N co-doped porous carbon(BN-C)via a salt template strategy.The aqueous ZICs assembled from BN-C cathode delivered a high capacity of 190.2 mAh·g^(-1)and a remarkable energy density of 105.1 Wh·kg^(-1).Moreover,systematic charac-terization verifies that B/N dual-doping promotes the physical adsorption/desorption kinetics of anion and the chemical absorption/desorption kinetics of Zn^(2+),thus improving the electrochemical performance of ZICs.In addition,the quasi-solid-state pouch-type battery exhibited excellent electrochemical durability and mechanical flexi-bility,demonstrating its vast application potential as a flexible power source.Overall,this research not only pre-sents a reasonable approach to the large-scale production of carbon cathode materials with excellent electrochemical performance but also strengthens the essential recognition of the charge storage mechanism of heteroatoms-doped carbon materials.展开更多
Boron doped diamond(BDD)electrode is a promising electrochemical material for detecting dopamine level in the human’s body.In this work,we developed a new doping source-graphite and solid boron oxide powders to synth...Boron doped diamond(BDD)electrode is a promising electrochemical material for detecting dopamine level in the human’s body.In this work,we developed a new doping source-graphite and solid boron oxide powders to synthesize BDD film with microwave plasma chemical vapor deposition,so as to avoid using toxic or corrosive dopants,such as boroethane and trimethylborate.The synthesized BDD film is pinhole free and with high doping density of 8.44×10^20 cm^-3 calculated from the Raman spectroscopy.Subsequently,Au nanospheres were decorated on the surface of BDD film to improve electrochemical performance of the BDD film.The Au nanoparticles modified BDD electrode demonstrates an excellent electrochemical response,a high sensitivity(in the range of 5μM-1 m M),and a low detection limit(~0.8μM)for detecting dopamine.展开更多
Simultaneously integrating heterogeneous interface,element doping,and metal decorating was a promising strategy to promote the visible-light-driven photocatalytic activity.Herein,we demonstrated a facile solvothermal ...Simultaneously integrating heterogeneous interface,element doping,and metal decorating was a promising strategy to promote the visible-light-driven photocatalytic activity.Herein,we demonstrated a facile solvothermal route for Ni-doped BiOBr/Bi^(0) with ZnO 3D hierarchical heterojunction(denoted as Z@B/BiNi).The optimal photocatalysts of Z@B/Bi-Ni sample presented a remarkable catalytic performance of high concentrations of tetracycline solution(40 mg/L)than those of the Z@B/Bi,Z@B,BOB and ZnO photocatalysts toward the visible-light-driven degradation.The enhanced photocatalytic mechanism can be proposed as follows:(ⅰ)3D hierarchical heterojunction provided more active sites and accelerated the separation of charge carriers for photocatalytic TC;(ⅱ)formation of oxygen vacancies on the surface over Z@B/Bi-Ni by in-situ reduction of Bi^(0) and Ni doping could serve as the active sites for oxygen activation to adsorb free O_(2) and generate more superoxide radicals;(ⅲ)SPR effect of Bi metal were beneficial to carrier separation and also act as the active site to trap O_(2) molecules.This work clarified the role of unique morphologies,surface plasmonic resonance(SPR)effect of metal Bi,and Ni doping in Z@B/Bi-Ni,and its photocatalytic reaction mechanism was proposed by a series of experiments,characterization and DFT calculations,arousing a new perspective to design hierarchical heterojunction photocatalysts.展开更多
The search for non-precious and efficient electrocatalysts towards the oxygen evolution reaction(OER)is of vital importance for the future advancement of multifarious renewable energy conversion/storage technologies.E...The search for non-precious and efficient electrocatalysts towards the oxygen evolution reaction(OER)is of vital importance for the future advancement of multifarious renewable energy conversion/storage technologies.Electronic modulation via heteroatom doping is recognized as one of the most forceful leverages to enhance the electrocatalytic activity.Herein,we demonstrate a delicate strategy for the in-situ confinement of S-doped Ni O nanoparticles into N-doped carbon nanotube/nanofiber-coupled hierarchical branched superstructures(labeled as S-Ni O@N-C NT/NFs).The developed strategy simultaneously combines enhanced thermodynamics via electronic regulation with accelerated kinetics via nanoarchitectonics.The S-doping into Ni O lattice and the 1 D/1 D-integrated hierarchical branched carbon substrate confer the resultant S-Ni O@N-C NT/NFs with regulated electronic configuration,enriched oxygen vacancies,convenient mass diffusion pathways and superior architectural robustness.Thereby,the SNi O@N-C NT/NFs display outstanding OER properties with an overpotential of 277 m V at 10 m A cm^(-2)and impressive long-term durability in KOH medium.Density functional theory(DFT)calculations further corroborate that introducing S-dopant significantly enhances the interaction with key oxygenate intermediates and narrow the band gap.More encouragingly,a rechargeable Zn-air battery using an air-cathode of Pt/C+S-Ni O@N-C NT/NFs exhibits a lower charge voltage and preferable cycling stability in comparison with the commercial Pt/C+Ru O_(2)counterpart.This study highlighting the concurrent consideration of electronic regulation,architectural design and nanocarbon hybridization may shed light on the future exploration of economical and efficient electrocatalysts.展开更多
While heteroatom doping serves as a powerful strategy for devising novel polycyclic aromatic hydrocarbons(PAHs), the further fine-tuning of optoelectronic properties via the precisely altering of doping patterns remai...While heteroatom doping serves as a powerful strategy for devising novel polycyclic aromatic hydrocarbons(PAHs), the further fine-tuning of optoelectronic properties via the precisely altering of doping patterns remains a challenge. Herein, by changing the doping positions of heteroatoms in a diindenopyrene skeleton, we report two isomeric boron, sulfur-embedded PAHs, named Anti-B_(2)S_(2) and Syn-B_(2)S_(2), as electron transporting semiconductors. Detailed structure-property relationship studies revealed that the varied heteroatom positions not only change their physicochemical properties, but also largely affect their solid-state packing modes and Lewis base-triggered photophysical responses. With their low-lying frontier molecular orbital levels, n-type characteristics with electron mobilities up to 1.5 × 10^(-3)cm^(2)V^(-1)s^(-1)were achieved in solution-processed organic field-effect transistors. Our work revealed the critical role of controlling heteroatom doping patterns for designing advanced PAHs.展开更多
A novel method for preparing Ta-doped Ti02 via using Ta2 05 as the doping source is proposed. The preparation process combines the hydrothernlal fluorination of Ta2O5 and the subsequent formation of Ta-doped TiO2 sol....A novel method for preparing Ta-doped Ti02 via using Ta2 05 as the doping source is proposed. The preparation process combines the hydrothernlal fluorination of Ta2O5 and the subsequent formation of Ta-doped TiO2 sol. The results show that the doped sample annealed at 393 K generates an unstable intermediate NH4 TiOF3, which converts into anatase TiO2 with the increase of temperature. After annealing at ≥673K, the Ta-doped TiO2 nanocrystals with the grain size 〈20nm are obtained. Both the XRD and TG-DSC results confirm that Ta doping prevents the anatase-rutile crystal transition of TiO2. The band gap values of the doped samples, as obtained by UV-vis diffuse reflectance spectra, are smaller than that of pure anatase TiO2. The first-principle pseudopotential method calculations indicate that Ta5＋ lies in the TiO2 lattice at the interstitial position.展开更多
Fe/N/C catalysts,synthesized through the pyrolysis of Fe-doped metal–organic framework (MOF) precursors,have attracted extensive attention owing to their promising oxygen reduction reaction (ORR) catalytic activity i...Fe/N/C catalysts,synthesized through the pyrolysis of Fe-doped metal–organic framework (MOF) precursors,have attracted extensive attention owing to their promising oxygen reduction reaction (ORR) catalytic activity in fuel cells and/or metal-air batteries.However,post-treatments (acid washing,second pyrolysis,and so on) are unavoidable to improve ORR catalytic activity and stability.The method for introducing Fe^(3+) sources (anhydrous Fe Cl_(3)) into the MOF structure,in particular,is a critical step that can avoid time-consuming post-treatments and result in more exposed Fe-N_(x) active sites.Herein,three different Fe doping strategies were systematically investigated to explore their influence on the types of active sites formed and ORR performance.Fe-NC(Zn^(2+)),synthesized by one-step pyrolysis of Fe doped ZIF-8 (Zn^(2+)) precursor which was obtained by adding the anhydrous Fe Cl_(3)source into the Zn(NO_(3))_(2)·6H_(2)O/methanol solution before mixing,possessed the highest Fe-N_(x)active sites due to the high-efficiency substitution of Zn^(2+)ions with Fe^(3+) ions during ZIF-8 growth,the strong interaction between Fe^(3+) ions and N atoms of 2-Methylimidazole (2-MIm),and ZIF-8’s micropore confinement effect.As a result,Fe-NC(Zn^(2+)) presented high ORR activity in the entire p H range (p H=1,7,and 13).At p H=13,Fe-NC(Zn^(2+)) exhibited a half-wave potential (E1/2) of 0.95 V (vs.reversible hydrogen electrode),which was 70 m V higher than that of commercial Pt/C.More importantly,Fe-NC(Zn^(2+)) showed superior ORR stability in neutral media without performance loss after 5,000 cycles.A record-high open-circuit voltage(1.9 V) was obtained when Fe-NC(Zn^(2+)) was used as a cathodic catalyst in assembled Mg-air batteries in neutral media.The assembled liquid and all-solid Mg-air batteries with high performance indicated that Fe-NC(Zn^(2+)) has enormous potential for use in flexible and wearable Mg-air batteries.展开更多
Gd- or Lu-doped long afterglow red phosphor Y2O2S：Sm^3＋ was synthesized using the high temperature flux fusion method. The obtained phosphors were analyzed using X-ray diffraction to determine the crystal structure,...Gd- or Lu-doped long afterglow red phosphor Y2O2S：Sm^3＋ was synthesized using the high temperature flux fusion method. The obtained phosphors were analyzed using X-ray diffraction to determine the crystal structure, and the phase analyses show that the product is in single phase. The luminescence spectra and decay curve were measured on a Hitachi F-4500 fluorescence spectrophotometer. The decay time was determined on an ST-900PM weak light photometer. The analyses show that host doping of Lu improves both luminescence and decay time of the materials. The concentration of doped Lu and Sm was varied in order to determine the optimal condition and to synthesize the product with the best properties. The mechanism of the long afterglow was also briefly discussed.展开更多
At three critical temperatures which were obtained by thermo-gravimetry-differential thermal analysis–differential scanning calorimetry（TG/DTG/DSC）curves of lanthanum nitrate crystal, the air thermal decomposition ...At three critical temperatures which were obtained by thermo-gravimetry-differential thermal analysis–differential scanning calorimetry（TG/DTG/DSC）curves of lanthanum nitrate crystal, the air thermal decomposition experiments and solid–liquid spray doping simulation procedures of lanthanum nitrate crystal were carried out, and their products were analyzed by X-ray diffraction（XRD）. Meanwhile, the spray doping processing of Mo O2–50 wt% La（NO3）3composite powder was undergone with lanthanum nitrate solution as the dopant,and doped Mo O2powder was analyzed by XRD. The results demonstrate that during the traditional solid–liquid spray doping processing, lanthanum nitrate, in the form of either crystal or aqueous solution, would be converted into La（NO3）3á4H2O by the dehydration reaction, rather than be decomposed to La2O3and NO or NO2. Therefore, it is inferred that the oxynitride gas produced from the process is attributed to the decomposition of residual HNO3in lanthanum nitrate crystal. The source of HNO3is supported by the chemical composition of lanthanum nitrate crystal.展开更多
In the present work, a sol-gel method was employed to prepare nanosized SrAl2O4 powders doped with Eu3＋ions. The raw nano- materials were thermally treated at 900 to 1100℃ for 3 h. The XRD analysis demonstrated that...In the present work, a sol-gel method was employed to prepare nanosized SrAl2O4 powders doped with Eu3＋ions. The raw nano- materials were thermally treated at 900 to 1100℃ for 3 h. The XRD analysis demonstrated that the powders were single-phase nanopowders with high crystallite dispersion. Our studies were focused on relating the luminescence properties of the Eu^3＋ dopant to the NC （nanocrystallites） size. This was achieved by varying the calcinations temperature between 900 and 1100 ℃. The average NC size varied accordingly between -36 and -75 nm. We found that size effect manifested mainly in the expansion of the cell volume and broadening of XRD peaks as indicated by Rietveld analysis. Moreover the emission and excitation spectra, although typical for Eu^3＋ ions, demonstrated some degree of variability with calcinations temperature and doping concentration. To explain these differences a detailed analysis of luminescence spectra by the Judd-Ofelt theory was performed.展开更多
AlGaN/GaN high electron mobility transistors （HEMTs） grown on Fe-modulation-doped （MD） and unintentionally doped （UID） GaN buffer layers are investigated and compared. Highly resistive GaN buffers （10^9Ω·...AlGaN/GaN high electron mobility transistors （HEMTs） grown on Fe-modulation-doped （MD） and unintentionally doped （UID） GaN buffer layers are investigated and compared. Highly resistive GaN buffers （10^9Ω·cm） are induced by individual mechanisms for the electron traps＇ formation： the Fe MD buffer （sample A） and the UID buffer with high density of edge-type dislocations （7.24×10^9cm^-2, sample B）. The 300K Hall test indicates that the mobility of sample A with Fe doping （2503cm^2V^-1s^-1） is much higher than sample B （1926cm^2V^-1s^-1） due to the decreased scattering effect on the two-dimensional electron gas. HEMT devices are fabricated on the two samples and pulsed I–V measurements are conducted. Device A shows better gate pinch-off characteristics and a higher threshold voltage （-2.63V） compared with device B （-3.71V）. Lower gate leakage current ｜IGS｜ of device A （3.32×10^-7A） is present compared with that of device B （8.29×10^-7A）. When the off-state quiescent points Q_2 （V GQ2=-8V, V DQ2=0V） are on, V th hardly shifts for device A while device B shows ＋0.21V positive threshold voltage shift, resulting from the existence of electron traps associated with the dislocations in the UID-GaN buffer layer under the gate. Under pulsed I–V and transconductance G m–V GS measurement, the device with the Fe MD-doped buffer shows more potential in improving reliability upon off-state stress.展开更多
基金supported by the National Natural Science Foundation of China(NSFC)(Nos.22178148 and 22278193)a Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions.
文摘As a catalyst of the air cathode in zinc-air batteries,tungstic acid ferrous(FeWO_(4)),a nanoscale transition metal tungstate,shows a broad application prospect in the oxygen reduction reaction(ORR).While FeWO_(4)possesses favorable electrochemical properties and thermodynamic stability,its intrinsic semiconductor characteristics result in a relatively slow electron transfer rate,limiting the ORR catalytic activity.In this work,the electronic structure of FeWO_(4)is significantly modulated by introducing phosphorus(P)atoms with abundant valence electrons.The P doping can adjust the electronic structure of FeWO_(4)and then optimize oxygen-containing intermediates'absorption/desorption efficiency to achieve improved ORR activity.Furthermore,the sodium chloride template is utilized to construct a porous carbon framework for anchoring phosphorus-doped iron tungstate(P-FeWO_(4)/PNC).The porous carbon skeleton provides numerous active sites for the absorption/desorption and redox reactions on the P-FeWO_(4)/PNC surface and serves as mass transport channels for reactants and intermediates.The P-FeWO_(4)/PNC demonstrates ORR performance(E1/2=0.86 V vs.RHE).Furthermore,the zinc-air batteries incorporating the P-FeWO_(4)/PNC composite demonstrate an increased peak power density(172.2 mW·cm^(-2)),high specific capacity(810.1 mAh·g^(-1)),and sustained long-term cycling stability lasting up to 240 h.This research not only contributes to the advancement of cost-effective tungsten-based non-precious metallic ORR catalysts,but also guides their utilization in zinc-air batteries.
基金Project supported by the National Natural Science Foundation of China (12174075)the Scientific and Technological Bases and Talents of Guangxi (Guike AD21220016)+1 种基金Guangxi Science and Technology Major Project(AA23073018)the special fund for Guangxi Bagui Scholars。
文摘Mn^(2+)-doped CsPbCl_(3)(Mn^(2+):CsPbCl_(3)) nanocrystals(NCs) have attracted considerable attention due to their unique strong and broad orange-red emission band,presenting promising applications in the field of photoelectric devices.However,pristine Mn^(2+):CsPbCl_(3)NCs commonly suffer from low photoluminescence quantum yield(PL QY) and stability issues.Herein,we introduced europium ions(Eu^(3+))into Mn^(2+):CsPbCl_(3)NCs via the thermal injection synthesis method to obtain high performance Eu^(3+)and Mn^(2+)codoped CsPbCl_(3)(Eu^(3+)/Mn^(2+):CsPbCl_(3)) NCs.The maximum PL QY of the resulting Eu^(3+)/Mn^(2+):CsPbCl_(3)NCs reaches up to 90.92%.It is found that the doping of Eu^(3+)ions significantly reduces the non-radiative recombination caused by high defect states,and improves the energy transfer efficiency from exciton to Mn^(2+),thereby boosting the PL performance.Moreover,doping Eu^(3+)ions notably improves the UV-light and water stability of Mn^(2+):CsPbCl_(3)NCs.We further demonstrate the application versatility of Eu^(3+)/Mn^(2+):CsPbCl_(3)NCs in white light emitting diodes(WLEDs) and optical anticounterfeiting applications.This work provides a valuable perspective for the attainment of high performance Mn^(2+):CsPbCl_(3)NCs and lays a foundation for the codoping of other lanthanide ions to adjust the luminescence properties of Mn^(2+):CsPbCl_(3)NCs.
基金supported by the Low-Cost Long-Life Batteries program,China(No.WL-24-08-01)the National Natural Science Foundation of China(No.22279007)。
文摘The outstanding performance of O3-type NaNi_(1/3)Fe_(1/3)Mn_(1/3)O_(2)(NFM111)at both high and low temperatures coupled with its impressive specific capacity makes it an excellent cathode material for sodium-ion batteries.However,its poor cycling,owing to highpressure phase transitions,is one of its disadvantages.In this study,Cu/Ti was introduced into NFM111 cathode material using a solidphase method.Through both theoretically and experimentally,this study found that Cu doping provides a higher redox potential in NFM111,improving its reversible capacity and charge compensation process.The introduction of Ti would enhance the cycling stability of the material,smooth its charge and discharge curves,and suppress its high-voltage phase transitions.Accordingly,the NaNi_(0.27)Fe_(0.28)Mn_(0.33)Cu_(0.05)Ti_(0.06)O_(2)sample used in the study exhibited a remarkable rate performance of 142.97 mAh·g^(-1)at 0.1 C(2.0-4.2 V)and an excellent capacity retention of 72.81%after 300 cycles at 1C(1C=150 mA·g^(-1)).
基金financially supported by the National Natural Science Foundation of China(No.22309067)the Open Project Program of the State Key Laboratory of Materials-Oriented Chemical Engineering,China(No.KL21-05)the Marine Equipment and Technology Institute,Jiangsu University of Science and Technology,China(No.XTCX202404)。
文摘This study focused on improving the cathode performance of Ba_(0.6)Sr_(0.4)Co_(0.85)Nb_(0.15)O_(3-δ)(BSCN)-based perovskite materials through molybdenum(Mo)doping.Pure BSCN and Mo-modified-BSCN—Ea_(0.6)Sr_(0.4)Co_(0.85)Nb_(0.1)Mo_(0.05)O_(3-δ)(B S CNM_(0.05)),Ba_(0.6)Sr_(0.4)Co_(0.85)Nb_(0.05)Mo_(0.1)O_(3-δ)(BSCNM_(0.1)),and Ba_(0.6)Sr_(0.4)Co_(0.85)Mo_(0.15)O_(3-δ)(BSCM)—with Mo doping contents of 5mol%,10mol%,and15mol%,respectively,were successfully prepared using the sol-gel method.The effects of Mo doping on the crystal structure,conductivity,thermal expansion coefficient,oxygen reduction reaction(ORR)activity,and electrochemical performance were systematically evaluated using X-ray diffraction analysis,thermally induced characterization,electrochemical impedance spectroscopy,and single-cell performance tests.The results revealed that Mo doping could improve the conductivity of the materials,suppress their thermal expansion effects,and significantly improve the electrochemical performance.Surface chemical state analysis using X-ray photoelectron spectroscopy revealed that 5mol%Mo doping could facilitate a high adsorbed oxygen concentration leading to enhanced ORR activity in the materials.Density functional theory calculations confirmed that Mo doping promoted the ORR activity in the materials.At an operating temperature of 600℃,the BSCNM_(0.05)cathode material exhibited significantly enhanced electrochemical impedance characteristics,with a reduced area specific resistance of 0.048Ω·cm~2,which was lower than that of the undoped BSCN matrix material by 32.39%.At the same operating temperature,an anode-supported single cell using a BSCNM_(0.05)cathode achieved a peak power density of 1477 mW·cm^(-2),which was 30.71%,56.30%,and 171.50%higher than those of BSCN,BSCNM_(0.1),and B SCM,respectively.The improved ORR activity and electrochemical performance of BSCNM_(0.05)indicate that it can be used as a cathode material in low-temperature solid oxide fuel cells.
文摘Sol--gol method was employed to synthesize Mg doped ZnO films on Si substrates. The annealing temperature-dependent structure and optical property of the produced samples were studied. An interesting result observed is that increasing Mg concentration in the studied samples induces the full width at half maximum （FWHM） of their near-band-edge （NBE） emission decrease and the defect related emission of the corresponding sample suppresses drastically. The possible mechanism of the observed result is discussed.
基金supported by the National Natural Science Foundation of China(Grant Nos.11004230,51172273,11290161,and 11027402)the National Key Basic Research Program of China(Grant Nos.2012CB933003 and 2013CB932603)the Innovative Project of the Chinese Academy of Sciences(GrantNo.KJCX2-YW-W35)
文摘Nitrogen-doped single-walled carbon nanotubes （CNx-SWNTs） with tunable dopant concentrations were synthesized by chemical vapor deposition （CVD）, and their structure and elemental composition were characterized by using transmission electron microscopy （TEM） in combination with electron energy loss spectroscopy （EELS）. By comparing the Raman spectra of pristine and doped nanotubes, we observed the doping-induced Raman G band phonon stiffening and 2D band phonon softening, both of which reflect doping-induced renormalization of the electron and phonon energies in the nan- otubes and behave as expected in accord with the n-type doping effect. On the basis of first principles calculations of the distribution of delocalized carrier density in both the pristine and doped nanotubes, we show how the n-type doping occurs when nitrogen heteroatoms are substitutionally incorporated into the honeycomb tube-shell carbon lattice.
基金supported by the Project of Shandong Province Higher Educational Science and Technology Program (No. J12LA09)the Applied Basic Research Project of the Ministry of Transport in China (No. 2013319817050)+1 种基金the National Natural Science Foundation of China (No. 21407098)the Promotive research fund for excellent young and middle-aged scientists of Shandong Province (No. BS2014HZ012)
文摘Na＋doped WO3 nanowire photocatalysts were prepared by using post-treatment（surface doping） and in situ（bulk doping） doping methods. Photocatalytic degradation of Methyl Blue was tested under visible light irradiation, the results showed that 1 wt.% Na＋bulk-doped WO3 performed better, with higher photoactivity than surface-doped WO3. Photoelectrochemical characterization revealed the differences in the photocatalytic process for surface doping and bulk doping. Uniform bulk doping could generate more electron–hole pairs, while minimizing the chance of electron–hole recombination. Some bulk properties such as the bandgap, Fermi level and band position could also be adjusted by bulk doping, but not by surface doping.
基金supported by the National Natural Science Foundation of China(21490581)China Petroleum&Chemical Corporation(317008-6)Guangxi Innovation Driven Development Foundation(AA17204092).
文摘Monometallic doping has proved its superiority in improving either permselectivity or H_(2) permeability of organosilica membranes for H_(2)/CO_(2) separation,but it is still challenging to break the trade-off effect.Herein,we report a series of Pd-Nb bimetallic doped 1,2-bis(triethoxysilyl)ethane(Pd-Nb-BTESE,PNB)membranes with different metal doping routes for simultaneously improving H_(2) permeance and H_(2)/CO_(2) permselectivity by the synergetic effects of Pd and Nb.The doped Pd can exist in the BTESE network as nanoparticles while the doped Nb is incorporated into BTESE network forming Nb-O-Si covalent bonds.The metal doping routes significantly influence the microstructure of PNB networks and gas separation performance of the PNB membranes.We found that the PNB membrane with Pd doping priority(PNB-Pd)exhibited the highest surface area and pore volume,comparing with Nb doping priority(PNB-Nb)or Pd-Nb simultaneous doping(PNB-PdNb).The PNB-Pd membrane could not only exhibit an excellent H_(2) permeance of~10^(−6) mol·m^(−2)·s^(−1)·Pa^(−1) but also a high H_(2)/CO_(2) permselectivity of 17.2.Our findings may provide novel insights into preparation of bimetallic doped organosilica membranes with excellent H_(2)/CO_(2) separation performance.
基金the Youth Talent Program Startup Foundation of Qufu Normal University(No.602601)the Natural Science Foundation of Rizhao(No.RZ2021ZR37)。
文摘Due to their superior fluorescence,phosphorescence,and catalytic capabilities,carbon dots(CDs),an emerging class of fluorescent carbon nanomaterials,have a wide range of potential applications.The properties of CDs have recently been controlled extensively by heteroatom doping.Boron atoms have been effectively doped into the structure of CDs due to their similar size to carbon atoms and excellent electron-absorbing ability to further improve the performance of CDs.In this review,we summarize the research progress of boron-doped CDs in recent years from the aspects of doping strategies,effects of boron doping on different performances of CDs and applications.Starting from the two aspects of single boron doping and boron and other atom co-doping,from different precursor materials to different synthesis methods,the doping strategies of boron-doped CDs are reviewed in detail.Then,the effects of boron doping on the fluorescence,phosphorescence and catalytic performance of CDs and applications of boron-doped CDs in optical sensors,information encryption and anti-counterfeiting are discussed.Finally,we further provide a prospect towards the future development of boron-doped CDs.
基金financially supported by the National Natural Science Foundation of China (Nos. 22179123 and 21471139)Shandong Provincial Natural Science Foundation, China (No. ZR2020ME038)+1 种基金Shandong Provincial Key R&D Plan and the Public Welfare Special Program, China (No. 2019GGX102038)the Fundamental Research Funds for the Central Universities (No. 201941010)
文摘Zinc ion capacitors(ZICs)have drawn increas-ing interest in energy storage devices because of their economic benefits,high safety,and long cycling life.Nevertheless,the lack of high-performance cathodes for ZICs remains a key challenge.Here,we fabricated B,N co-doped porous carbon(BN-C)via a salt template strategy.The aqueous ZICs assembled from BN-C cathode delivered a high capacity of 190.2 mAh·g^(-1)and a remarkable energy density of 105.1 Wh·kg^(-1).Moreover,systematic charac-terization verifies that B/N dual-doping promotes the physical adsorption/desorption kinetics of anion and the chemical absorption/desorption kinetics of Zn^(2+),thus improving the electrochemical performance of ZICs.In addition,the quasi-solid-state pouch-type battery exhibited excellent electrochemical durability and mechanical flexi-bility,demonstrating its vast application potential as a flexible power source.Overall,this research not only pre-sents a reasonable approach to the large-scale production of carbon cathode materials with excellent electrochemical performance but also strengthens the essential recognition of the charge storage mechanism of heteroatoms-doped carbon materials.
基金financially supported by the National Science Fund for Distinguished Young Scholars(No.51625201)the National Natural Science Foundation of China No.51,702,066+2 种基金the National Key Research and Development Program of China(No.2016YFE0201600)the Key Laboratory of Micro-systems and Micro-structures Manufacturing,Ministry of Education,Harbin Institute of Technology(No.2016KM001)the Innovative research group of NSFC11421091。
文摘Boron doped diamond(BDD)electrode is a promising electrochemical material for detecting dopamine level in the human’s body.In this work,we developed a new doping source-graphite and solid boron oxide powders to synthesize BDD film with microwave plasma chemical vapor deposition,so as to avoid using toxic or corrosive dopants,such as boroethane and trimethylborate.The synthesized BDD film is pinhole free and with high doping density of 8.44×10^20 cm^-3 calculated from the Raman spectroscopy.Subsequently,Au nanospheres were decorated on the surface of BDD film to improve electrochemical performance of the BDD film.The Au nanoparticles modified BDD electrode demonstrates an excellent electrochemical response,a high sensitivity(in the range of 5μM-1 m M),and a low detection limit(~0.8μM)for detecting dopamine.
基金supported by the National Natural Science Foundation of China(No.21576211)Tianjin Program of Science and Technology(No.21ZYJDJC00100)+1 种基金Tianjin Innovative Research Team in Universities(No.TD13-5031)Tianjin 131 Research Team of Innovative Talents。
文摘Simultaneously integrating heterogeneous interface,element doping,and metal decorating was a promising strategy to promote the visible-light-driven photocatalytic activity.Herein,we demonstrated a facile solvothermal route for Ni-doped BiOBr/Bi^(0) with ZnO 3D hierarchical heterojunction(denoted as Z@B/BiNi).The optimal photocatalysts of Z@B/Bi-Ni sample presented a remarkable catalytic performance of high concentrations of tetracycline solution(40 mg/L)than those of the Z@B/Bi,Z@B,BOB and ZnO photocatalysts toward the visible-light-driven degradation.The enhanced photocatalytic mechanism can be proposed as follows:(ⅰ)3D hierarchical heterojunction provided more active sites and accelerated the separation of charge carriers for photocatalytic TC;(ⅱ)formation of oxygen vacancies on the surface over Z@B/Bi-Ni by in-situ reduction of Bi^(0) and Ni doping could serve as the active sites for oxygen activation to adsorb free O_(2) and generate more superoxide radicals;(ⅲ)SPR effect of Bi metal were beneficial to carrier separation and also act as the active site to trap O_(2) molecules.This work clarified the role of unique morphologies,surface plasmonic resonance(SPR)effect of metal Bi,and Ni doping in Z@B/Bi-Ni,and its photocatalytic reaction mechanism was proposed by a series of experiments,characterization and DFT calculations,arousing a new perspective to design hierarchical heterojunction photocatalysts.
基金financially supported by the National Natural Science Foundation of China(21972068,21875112,22072067,21878047,22075290 and 21676056)the Qing Lan Project of Jiangsu Province(1107040167)+3 种基金the Postgraduate Research&Practice Innovation Program of Jiangsu Province(KYCX20_0121)the China Scholarship Council(CSC,202006090294)the Fundamental Research Funds for the Central Universities(3207042101D)A Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)(1107047002)。
文摘The search for non-precious and efficient electrocatalysts towards the oxygen evolution reaction(OER)is of vital importance for the future advancement of multifarious renewable energy conversion/storage technologies.Electronic modulation via heteroatom doping is recognized as one of the most forceful leverages to enhance the electrocatalytic activity.Herein,we demonstrate a delicate strategy for the in-situ confinement of S-doped Ni O nanoparticles into N-doped carbon nanotube/nanofiber-coupled hierarchical branched superstructures(labeled as S-Ni O@N-C NT/NFs).The developed strategy simultaneously combines enhanced thermodynamics via electronic regulation with accelerated kinetics via nanoarchitectonics.The S-doping into Ni O lattice and the 1 D/1 D-integrated hierarchical branched carbon substrate confer the resultant S-Ni O@N-C NT/NFs with regulated electronic configuration,enriched oxygen vacancies,convenient mass diffusion pathways and superior architectural robustness.Thereby,the SNi O@N-C NT/NFs display outstanding OER properties with an overpotential of 277 m V at 10 m A cm^(-2)and impressive long-term durability in KOH medium.Density functional theory(DFT)calculations further corroborate that introducing S-dopant significantly enhances the interaction with key oxygenate intermediates and narrow the band gap.More encouragingly,a rechargeable Zn-air battery using an air-cathode of Pt/C+S-Ni O@N-C NT/NFs exhibits a lower charge voltage and preferable cycling stability in comparison with the commercial Pt/C+Ru O_(2)counterpart.This study highlighting the concurrent consideration of electronic regulation,architectural design and nanocarbon hybridization may shed light on the future exploration of economical and efficient electrocatalysts.
基金the National Natural Science Foundation of China (Nos.22375059, 22005133, 51922039 and52273174)Shenzhen Science and Technology Program (No.RCJC20200714114434015)+1 种基金Science and Technology Innovation Program of Hunan Province (No.2020RC5033)National Key Research and Development Program of China (No.2020YFC1807302) for financial support。
文摘While heteroatom doping serves as a powerful strategy for devising novel polycyclic aromatic hydrocarbons(PAHs), the further fine-tuning of optoelectronic properties via the precisely altering of doping patterns remains a challenge. Herein, by changing the doping positions of heteroatoms in a diindenopyrene skeleton, we report two isomeric boron, sulfur-embedded PAHs, named Anti-B_(2)S_(2) and Syn-B_(2)S_(2), as electron transporting semiconductors. Detailed structure-property relationship studies revealed that the varied heteroatom positions not only change their physicochemical properties, but also largely affect their solid-state packing modes and Lewis base-triggered photophysical responses. With their low-lying frontier molecular orbital levels, n-type characteristics with electron mobilities up to 1.5 × 10^(-3)cm^(2)V^(-1)s^(-1)were achieved in solution-processed organic field-effect transistors. Our work revealed the critical role of controlling heteroatom doping patterns for designing advanced PAHs.
基金Supported by the Fundamental Research Funds for the Central Universities under Grant No 2012QNA03
文摘A novel method for preparing Ta-doped Ti02 via using Ta2 05 as the doping source is proposed. The preparation process combines the hydrothernlal fluorination of Ta2O5 and the subsequent formation of Ta-doped TiO2 sol. The results show that the doped sample annealed at 393 K generates an unstable intermediate NH4 TiOF3, which converts into anatase TiO2 with the increase of temperature. After annealing at ≥673K, the Ta-doped TiO2 nanocrystals with the grain size 〈20nm are obtained. Both the XRD and TG-DSC results confirm that Ta doping prevents the anatase-rutile crystal transition of TiO2. The band gap values of the doped samples, as obtained by UV-vis diffuse reflectance spectra, are smaller than that of pure anatase TiO2. The first-principle pseudopotential method calculations indicate that Ta5＋ lies in the TiO2 lattice at the interstitial position.
基金supported by the National Natural Science Foundation of China(22171266)the FJIRSM&IUE Joint Research Fund(RHZX-2019-002)+2 种基金the STS Project(KFJ-STS-QYZD-2021-09002)the National Key Basic Research Program of China(2017YFA0403402)the Project of the National Natural Science Foundation of China(U1932119)。
文摘Fe/N/C catalysts,synthesized through the pyrolysis of Fe-doped metal–organic framework (MOF) precursors,have attracted extensive attention owing to their promising oxygen reduction reaction (ORR) catalytic activity in fuel cells and/or metal-air batteries.However,post-treatments (acid washing,second pyrolysis,and so on) are unavoidable to improve ORR catalytic activity and stability.The method for introducing Fe^(3+) sources (anhydrous Fe Cl_(3)) into the MOF structure,in particular,is a critical step that can avoid time-consuming post-treatments and result in more exposed Fe-N_(x) active sites.Herein,three different Fe doping strategies were systematically investigated to explore their influence on the types of active sites formed and ORR performance.Fe-NC(Zn^(2+)),synthesized by one-step pyrolysis of Fe doped ZIF-8 (Zn^(2+)) precursor which was obtained by adding the anhydrous Fe Cl_(3)source into the Zn(NO_(3))_(2)·6H_(2)O/methanol solution before mixing,possessed the highest Fe-N_(x)active sites due to the high-efficiency substitution of Zn^(2+)ions with Fe^(3+) ions during ZIF-8 growth,the strong interaction between Fe^(3+) ions and N atoms of 2-Methylimidazole (2-MIm),and ZIF-8’s micropore confinement effect.As a result,Fe-NC(Zn^(2+)) presented high ORR activity in the entire p H range (p H=1,7,and 13).At p H=13,Fe-NC(Zn^(2+)) exhibited a half-wave potential (E1/2) of 0.95 V (vs.reversible hydrogen electrode),which was 70 m V higher than that of commercial Pt/C.More importantly,Fe-NC(Zn^(2+)) showed superior ORR stability in neutral media without performance loss after 5,000 cycles.A record-high open-circuit voltage(1.9 V) was obtained when Fe-NC(Zn^(2+)) was used as a cathodic catalyst in assembled Mg-air batteries in neutral media.The assembled liquid and all-solid Mg-air batteries with high performance indicated that Fe-NC(Zn^(2+)) has enormous potential for use in flexible and wearable Mg-air batteries.
基金Project supported bythe Foundation of USTB,China
文摘Gd- or Lu-doped long afterglow red phosphor Y2O2S：Sm^3＋ was synthesized using the high temperature flux fusion method. The obtained phosphors were analyzed using X-ray diffraction to determine the crystal structure, and the phase analyses show that the product is in single phase. The luminescence spectra and decay curve were measured on a Hitachi F-4500 fluorescence spectrophotometer. The decay time was determined on an ST-900PM weak light photometer. The analyses show that host doping of Lu improves both luminescence and decay time of the materials. The concentration of doped Lu and Sm was varied in order to determine the optimal condition and to synthesize the product with the best properties. The mechanism of the long afterglow was also briefly discussed.
基金financially supported by the National Science and Technology Support Program of China (No. 2012BAE06B02)
文摘At three critical temperatures which were obtained by thermo-gravimetry-differential thermal analysis–differential scanning calorimetry（TG/DTG/DSC）curves of lanthanum nitrate crystal, the air thermal decomposition experiments and solid–liquid spray doping simulation procedures of lanthanum nitrate crystal were carried out, and their products were analyzed by X-ray diffraction（XRD）. Meanwhile, the spray doping processing of Mo O2–50 wt% La（NO3）3composite powder was undergone with lanthanum nitrate solution as the dopant,and doped Mo O2powder was analyzed by XRD. The results demonstrate that during the traditional solid–liquid spray doping processing, lanthanum nitrate, in the form of either crystal or aqueous solution, would be converted into La（NO3）3á4H2O by the dehydration reaction, rather than be decomposed to La2O3and NO or NO2. Therefore, it is inferred that the oxynitride gas produced from the process is attributed to the decomposition of residual HNO3in lanthanum nitrate crystal. The source of HNO3is supported by the chemical composition of lanthanum nitrate crystal.
基金Project supported by the Polish Ministry of Science and Higher Education (NN 204331537)National Science Centre (N N507 372335)
文摘In the present work, a sol-gel method was employed to prepare nanosized SrAl2O4 powders doped with Eu3＋ions. The raw nano- materials were thermally treated at 900 to 1100℃ for 3 h. The XRD analysis demonstrated that the powders were single-phase nanopowders with high crystallite dispersion. Our studies were focused on relating the luminescence properties of the Eu^3＋ dopant to the NC （nanocrystallites） size. This was achieved by varying the calcinations temperature between 900 and 1100 ℃. The average NC size varied accordingly between -36 and -75 nm. We found that size effect manifested mainly in the expansion of the cell volume and broadening of XRD peaks as indicated by Rietveld analysis. Moreover the emission and excitation spectra, although typical for Eu^3＋ ions, demonstrated some degree of variability with calcinations temperature and doping concentration. To explain these differences a detailed analysis of luminescence spectra by the Judd-Ofelt theory was performed.
基金Supported by the National Natural Science Foundation of China under Grant Nos 61204017 and 61334002the National Basic Research Program of Chinathe National Science and Technology Major Project of China
文摘AlGaN/GaN high electron mobility transistors （HEMTs） grown on Fe-modulation-doped （MD） and unintentionally doped （UID） GaN buffer layers are investigated and compared. Highly resistive GaN buffers （10^9Ω·cm） are induced by individual mechanisms for the electron traps＇ formation： the Fe MD buffer （sample A） and the UID buffer with high density of edge-type dislocations （7.24×10^9cm^-2, sample B）. The 300K Hall test indicates that the mobility of sample A with Fe doping （2503cm^2V^-1s^-1） is much higher than sample B （1926cm^2V^-1s^-1） due to the decreased scattering effect on the two-dimensional electron gas. HEMT devices are fabricated on the two samples and pulsed I–V measurements are conducted. Device A shows better gate pinch-off characteristics and a higher threshold voltage （-2.63V） compared with device B （-3.71V）. Lower gate leakage current ｜IGS｜ of device A （3.32×10^-7A） is present compared with that of device B （8.29×10^-7A）. When the off-state quiescent points Q_2 （V GQ2=-8V, V DQ2=0V） are on, V th hardly shifts for device A while device B shows ＋0.21V positive threshold voltage shift, resulting from the existence of electron traps associated with the dislocations in the UID-GaN buffer layer under the gate. Under pulsed I–V and transconductance G m–V GS measurement, the device with the Fe MD-doped buffer shows more potential in improving reliability upon off-state stress.
