A novel Fe-doping three-dimensional fiower-like Bi_(7)O_(9)I_(3) microspheres with plasmonic Bi and rich surface oxygen vacancies(Fe-Bi/Bi_(7)O_(9)I_(3)/OVs)was prepared as catalysts,and further coupled with natural a...A novel Fe-doping three-dimensional fiower-like Bi_(7)O_(9)I_(3) microspheres with plasmonic Bi and rich surface oxygen vacancies(Fe-Bi/Bi_(7)O_(9)I_(3)/OVs)was prepared as catalysts,and further coupled with natural air diffusion electrode(NADE)to construct the heterogeneous visible-light-driven photoelectro-Fenton(HEVL-PEF)process to enhance the degradation and mineralization of tetracycline(TC).Interfacial≡Fe sites,OVs and Bi metal were simultaneously constructed via Fe doping,which effectively improved visible light absorption and the separation efficiency of photogenerated carriers to further accelerate the transformation of Fe(Ⅲ)to Fe(Ⅱ),achieving Fenton reaction recycling.HE-VL-PEF process could achieve enhanced treatment of pollutants,thanks to the synergistic effect of electro-Fenton(EF)and photo-Fenton(PF).NADE exhibited excellent H_(2)O_(2) electrosynthesis without external oxygen-pumping equipment.Under the irradiation of visible light,Fe-Bi/Bi_(7)O_(9)I_(3)/OVs could achieve more photoelectrons to accelerate the transformation of Fe(Ⅲ)to Fe(Ⅱ)or directly activate H2O2.DFT calculations also clearly demonstrated that except for the fast charge separation and transfer,Fe-Bi/Bi_(7)O_(9)I_(3)/OVs could achieve a faster electron transport between Fe-O,facilitating Fe site acquire more electron.Consequently,the Fe-Bi/Bi_(7)O_(9)I_(3)/OVs in HE-VL-PEF process presented performance superiorities including excellent pollutant removal(91.91%),low electric energy consumption of 66.34 k Wh/kg total organic carbon(TOC),excellent reusability and wide p H adaptability(3–9).展开更多
The microstructure, dielectric properties and chemical state of Ti element on BaTi_4O_9 (f)/(0.64 BaTi_4O_9-0.36BaPr_2Ti_4O_(12)) composites sample surface were characterized by X-ray diffraction (XRD), Transmission e...The microstructure, dielectric properties and chemical state of Ti element on BaTi_4O_9 (f)/(0.64 BaTi_4O_9-0.36BaPr_2Ti_4O_(12)) composites sample surface were characterized by X-ray diffraction (XRD), Transmission electron microscopy (TEM), LCR meter method and X-ray photoelectron spectroscopy (XPS). The results show that the system is composed of BaTi_4O_9 and BaPr_2Ti_4O_(12) two phases. Pr ions are distributed in the BaWi_4O_9 grains and the segregation of Pr ions was observed on the grain boundaries of BaTi_4O_9/BaTi_4O_9. The content of Ti^(3+) and Ti^(2+) decrease in the BPT system composites due to the addition of BaTi_4O_9 fibers, which improved the dielectric properties of the system. BPT10 sample with 10% BaTi_4O_9 fibers, has the best dielectric properties in the system, its ε_r = 64, tan δ= 1×10^(-4)(at 1 MHz) , and it may be a potential candidate for microwave dielectric ceramics.展开更多
The hysteresis loop changes of ferroelecric SrBi_2 Ta_2 O_9 (SBT) thin films(330nm) us the temperature of forming gas (5 percent hydrogen+95 percent nitrogen) annealing weremeasured when the annealing time was 1min an...The hysteresis loop changes of ferroelecric SrBi_2 Ta_2 O_9 (SBT) thin films(330nm) us the temperature of forming gas (5 percent hydrogen+95 percent nitrogen) annealing weremeasured when the annealing time was 1min and 10min. The selected annealing temperature was at 100deg C,200 deg C 250 deg C, 300 deg C, 350 deg C,400 deg C and 450 deg C, respectively. Our resultsshowed that the ferroelectric properties were easily destroyed and the leakage current changedabruptly when the SBT thin films were in their ferroelectric phase (<270 deg C). The space chargesat the grain boundary may take an important role' in absorption polarity molecular hydrogen when theSBT thin films were in the ferroelectric phase. The oxygen recovery experiments were also performedand investigated in this work.展开更多
Preparation of homogeneous Ca_ 3-xLa_xCo_4O_9 (x=0～0.4) single-phase ceramic powders was described using a tartrate complex method. The results show Ca3Co_4O_9 phase can be obtained by calcining the dry gel at 750 ℃...Preparation of homogeneous Ca_ 3-xLa_xCo_4O_9 (x=0～0.4) single-phase ceramic powders was described using a tartrate complex method. The results show Ca3Co_4O_9 phase can be obtained by calcining the dry gel at 750 ℃ for 5 h. The Ca_ 3-xLa_xCo_4O_9 ceramics have been prepared by spark plasma sintering at 800 ℃ for 5 min. Spark plasma sintering process is effective in synthesis of Ca_ 3-xLa_xCo_4O_9 compact ceramics. The thermal conductivity of Ca_ 3-xLa_xCo_4O_9 bulks was investigated from room temperature to 700 ℃. The results show that Ca_ 2.7La_ 0.3Co_4O_9 has lowest thermal conductivity due to the increasing of phonon scattering by La substitution.展开更多
Bismuth ferrite（Bi_2Fe_4O_9） thin films were grown on p-type Si（100） substrate by radio-frequency magnetron sputtering at 873 K. X-ray diffraction, field emission scanning electron microscopy and Raman spectroscop...Bismuth ferrite（Bi_2Fe_4O_9） thin films were grown on p-type Si（100） substrate by radio-frequency magnetron sputtering at 873 K. X-ray diffraction, field emission scanning electron microscopy and Raman spectroscopy studies revealed that the grown films have single-phase polycrystalline nature and are crystallized in orthorhombic structure. The grain size of the grown thin films was found to increase（56–130 nm） with sputtering power. Atomic force microscopy images clearly illustrated that the grown thin films have smooth surface. Energy-dispersive X-ray analysis revealed the presence of Bi, Fe and O elements with desired ratio and also the absence of impurities in the grown films. Analysis of ferroelectric hysteresis loops revealed that the remanent polarization and coercive field increase with the increase in sputtering power. Vicker＇s hardness analysis showed that the hardness of films strongly depends on the grain size and film thickness, which are mainly determined by the sputtering power. The above observations revealed that Bi_2Fe_4O_9 thin film deposited at higher sputtering power has good crystallinity and shows better electrical properties.展开更多
Single-phase La_（2–x）Nd_xMo_2O_9（0≤x≤1.8） compounds were prepared using solid-state reaction technique. Their structural and thermal p roperties were characterized by room and high temperatures X-ray diffractio...Single-phase La_（2–x）Nd_xMo_2O_9（0≤x≤1.8） compounds were prepared using solid-state reaction technique. Their structural and thermal p roperties were characterized by room and high temperatures X-ray diffraction（XRD）, thermo gravimetric analysis-differential scanningcalorimetry（TG-DSC）, and high temperature Raman spectra. The transport properties were investigated using D.C. four-probe technique and Hebb-Wagner polarization method. The substitution limit of Nb^（3＋） in La_（2–x）Nd_xMo_2O_9 was determined to be in the range of 1.8展开更多
Dyeing wastewater poses a serious threat to environmental protection and industrial development.The piezoelectric effect can be used to optimize the band structure of semiconductors and improve the photon efficiency o...Dyeing wastewater poses a serious threat to environmental protection and industrial development.The piezoelectric effect can be used to optimize the band structure of semiconductors and improve the photon efficiency of photocatalysts.Bi_(2)Fe_(4)O_(9),a narrow gap semiconductor with piezoelectric effect,was prepared by a hydrothermal synthesis method for the degradation of reactive dye KN-R.The results show that the degradation efficiency of KN-R can be significantly improved by piezo-photocatalysis,and the degradation rate constant of piezo-photocatalysis k_(pi-ph)is about 3.4 times as large as the degradation rate constant of piezoelectric catalysis k_(pi)and about 2.6 times as large as the degradation rate constant of photocatalysis k_(ph).At a pH value of 3 and a lower KN-R mass concentration(60 mg/L),a higher degradation efficiency(98.5%)is achieved.CO_(3)^(2-)and cationic surfactant(CTAB)inhibit the degradation of KN-R.It is proved that the contributions of different active species to the degradation of KN-R follow the order:·OH,·O_(2)^(-),h^(+),and^(1)O_(2).The possible mechanism of piezo-photocatalytic degradation of KN-R was discussed.The photoexcitation generates a large amount of free charges,and the piezoelectric effect modulates the energy band structure of Bi_(2)Fe_(4)O_(9)and promotes the separation of photogenerated electron-hole pairs.The synergistic effect of the two factors significantly improves the degradation efficiency of KN-R.展开更多
Piezo-photocatalysis is an emerging photocatalytic technology in which the piezoelectric electric field drives photogenerated carriers to separate,thereby improving the photocatalytic activity of the catalyst.Herein,s...Piezo-photocatalysis is an emerging photocatalytic technology in which the piezoelectric electric field drives photogenerated carriers to separate,thereby improving the photocatalytic activity of the catalyst.Herein,solid phase and one-step molten salt processes were used to prepare SrBi_(2)Nb_(2)O_(9)(SBN)powders with granular and sheet morphologies,respectively.The influence of micromorphology on the piezo-photocatalytic performances of SBN was determined by degrading ciprofloxacin hydrochloride(CIP).SBN nanosheets demonstrate remarkable piezo-photocatalytic performance,achieving an 89.13%CIP degradation rate in 60 min and an apparent rate constant of 34.73×10^(-3) min^(-1).This performance is approximately 2.65 times higher than that of granular SBN and outperformed many recently reported piezo-photocatalysts under similar experimental conditions.Free radical trapping techniques,electron spin resonance spectroscopy and liquid chromatography-mass spectrometry are utilized to study the potential paths and mechanisms of CIP degradation.Piezoresponse force microscopy and finite element simulation show that the piezo-response of SBN nanosheets is significantly higher than that of granular SBN.SBN nanosheets achieve high degradation efficiency due to their optimized conduction band positions and enhanced piezoelectric effect,facilitated by the two-dimensional nanosheet structures.In this work,the piezoelectric internal electric field of piezoelectric catalysts can be increased by tuning the catalyst morphology,which points to a possible direction for the production of high-performance piezoelectric catalysts.展开更多
The rational design of composition and microstructure is a proven strategy for developing multifunctional high-performance electromagnetic wave(EMW)absorbers.In this study,a sandwich-structured multilayer nanoplate-li...The rational design of composition and microstructure is a proven strategy for developing multifunctional high-performance electromagnetic wave(EMW)absorbers.In this study,a sandwich-structured multilayer nanoplate-like Bi_(2)Fe_(4)O_(9)@Polypyrrole(BFO@PPy)heterostructure was successfully designed and fabricated using an efficient microwave hydrothermal method and an in situ polymerization process.Specifically,Bi_(2)Fe_(4)O_(9)enhances the chemical activity of ammonium persulfate,which in turn initiates the polymerization of pyrrole monomers,resulting in the formation of BFO@PPy heterostructures.The thickness of the PPy coating layer in the BFO@PPy composite can be precisely controlled at the nanoscale,optimizing electromagnetic parameters,conduction losses and interface polarization loss.The fabricated BFO@PPy composite achieves a minimum reflection loss(RL_(min))of-57.8 dB at a thickness of 2.5 mm and an effective absorption bandwidth(EAB)of 6.96 GHz.Furthermore,the EMW absorption performance and mechanism were systematically validated through theoretical calculations,radar cross-sectional simulations(RCS),and first-principles analysis.Notably,the RCS simulation of a 1:1 scale F-22 Raptor fighter model provides a realistic evaluation of the composite's EMW absorption potential in military applications.The efficient fabrication method and superior electromagnetic absorption performance make BFO@PPy a promising candidate for use in complex electromagnetic environments and military domains.Additionally,the BFO@PPy composite exhibits rapid electrothermal conversion at a low voltage(3V),achieving active infrared camouflage within a controllable temperature range,further highlighting its multifunctional properties.展开更多
Bi_(2)Fe_(4)O_(9) nanosheets were prepared using a hydrothermal method,followed by the introduction of NaBH_(4) and hightemperature calcination,which successfully induced strong ferromagnetism in the material at room ...Bi_(2)Fe_(4)O_(9) nanosheets were prepared using a hydrothermal method,followed by the introduction of NaBH_(4) and hightemperature calcination,which successfully induced strong ferromagnetism in the material at room temperature(M_(S)=10.22 emu/g and M_(r)=2.93 emu/g).This work demonstrates for the first time that Bi_(2)Fe_(4)O_(9) can exhibit such strong ferromagnetism at room temperature,with potential for further enhancements.Meanwhile,the ferroelectric properties of the samples were investigated.X-ray diffraction confirmed that the samples were single-phase with no detectable impurities.Based on a series of characterization analyses,it is inferred that Bi vacancies contribute to the observed strong magnetism.展开更多
MnO_(2)-doped Ca_(0.97)Bi_(2.03)Nb_(2)O_(9) ceramics with greatly improved piezoelectric performance were prepared via conventional solid state sintering method.The effects of MnO_(2) doping on the microstructure and ...MnO_(2)-doped Ca_(0.97)Bi_(2.03)Nb_(2)O_(9) ceramics with greatly improved piezoelectric performance were prepared via conventional solid state sintering method.The effects of MnO_(2) doping on the microstructure and electrical properties of Ca_(0.97)Bi_(2.03)Nb_(2)O_(9) ceramics were studied.X-ray diffraction(XRD)analysis and Rietveld refinement revealed a reduction in orthorhombicity with MnO_(2) doping,which contributed to the enhancement of the piezoelectric properties.Furthermore,the introduction of MnO_(2) lowered the sintering temperature,thereby reducing the formation of oxygen vacancies in the ceramic.The optimal performance was achieved in the Ca_(0.97)Bi_(2.03)Nb_(2)O_(9)−0.3wt.%MnO_(2) sample,exhibiting a piezoelectric coefficient(d33)of 13.6 pC/N,a DC resistivity of 3×10^(6)Ω·cm at 500℃,and a Curie temperature of 965℃.Additionally,all doped samples demonstrated excellent thermal stability over a wide temperature range,from room temperature to 900℃.展开更多
The gallate salts are frequently employed as matrix for mechanoluminescence(ML)materials largely due to their plentiful defect energy levels and robust piezoelectric characteristics.Nevertheless,the ML performance of ...The gallate salts are frequently employed as matrix for mechanoluminescence(ML)materials largely due to their plentiful defect energy levels and robust piezoelectric characteristics.Nevertheless,the ML performance of specific gallate materials is inferior to that of sulfides and fluorides and thus requires improvement.To address this issue,it is essential to engineer appropriate lattice defects in order to facilitate the advancement of new elastic ML materials.Therefore,in the present study,a series of Ca_(3)Ga_(4)O_(9):0.01 Bi^(3+),xTb^(3+)(x=0.01,0.02,0.03,0.04,0.05 and 0.06)was synthesized using the traditional high-temperature solid-state method.Furthermore,a non-intrinsic defect control strategy utilising Bi^(3+)ions is presented,which serves to enhance the performance of calcium gallate.The ML intensity is enhanced by 112%in comparison to the undoped samples(concentration of Tb^(3+)is 0.04),resulting in an improved linearity between mechanical loading and ML intensity,along with the achievement of dualmode photoluminescence(PL).By analysing the crystal structure,PL,ML,and thermoluminescence(TL)properties of Ca_(3)Ga_(4)O_(9):Bi^(3+),Tb^(3+)(CGO:Bi^(3+),Tb^(3+)),coupled with the first principles calculations using density functional theory(DFT),the ML mechanism of CGO:Bi^(3+),Tb^(3+)was elucidated.This leads to the development of a versatile anti-counterfeiting device with both flexible and rigid multi-mode capabilities.展开更多
Photocatalytic hydrogen evolution is of great importance with the proceeding of dual carbon goals,for inorganic catalysts have been explored with high efficiency.The structure and properties of oxide composites might ...Photocatalytic hydrogen evolution is of great importance with the proceeding of dual carbon goals,for inorganic catalysts have been explored with high efficiency.The structure and properties of oxide composites might take advantage of each compound and display an increased activity.In our previous study,boron doped-Cu_(3)NiBaTi_(4)O_(9)possessed a porous structure and its photocurrent response was apparent.To further verify its excellent catalytic activity,Al_(2)O_(3),and SiO_(2) were selected to replace with BaTi_(4)O_(9)to prepare different composites.The physical and chemical features of each sample were characterized with SEM,XRD,XPS,etc.to reveal their structural variations.Correspondingly,the H_(2)evolution rate was investigated with gas chromatography under the sunlight irritation.A distinct hydrogen yield was recorded with prepared samples.Further,the projected density of states analysis was taken through density functional theory calculations to appreciate the conduction band of the composite.The offered electrons during the photocatalytic process and the potential applicability of composites in the field of photocatalysis was verified.展开更多
基金financially supported by Key Project of Natural Science Foundation of Tianjin(No.21JCZDJC00320)National Key R&D Program International Cooperation Project(No.2021YFE0106500)+3 种基金Natural Science Foundation of China(No.52170085)Fundamental Research Funds for the Central UniversitiesNankai UniversityNational Research Foundation IRGChina/South Africa Research Cooperation Programme(No.132793)。
文摘A novel Fe-doping three-dimensional fiower-like Bi_(7)O_(9)I_(3) microspheres with plasmonic Bi and rich surface oxygen vacancies(Fe-Bi/Bi_(7)O_(9)I_(3)/OVs)was prepared as catalysts,and further coupled with natural air diffusion electrode(NADE)to construct the heterogeneous visible-light-driven photoelectro-Fenton(HEVL-PEF)process to enhance the degradation and mineralization of tetracycline(TC).Interfacial≡Fe sites,OVs and Bi metal were simultaneously constructed via Fe doping,which effectively improved visible light absorption and the separation efficiency of photogenerated carriers to further accelerate the transformation of Fe(Ⅲ)to Fe(Ⅱ),achieving Fenton reaction recycling.HE-VL-PEF process could achieve enhanced treatment of pollutants,thanks to the synergistic effect of electro-Fenton(EF)and photo-Fenton(PF).NADE exhibited excellent H_(2)O_(2) electrosynthesis without external oxygen-pumping equipment.Under the irradiation of visible light,Fe-Bi/Bi_(7)O_(9)I_(3)/OVs could achieve more photoelectrons to accelerate the transformation of Fe(Ⅲ)to Fe(Ⅱ)or directly activate H2O2.DFT calculations also clearly demonstrated that except for the fast charge separation and transfer,Fe-Bi/Bi_(7)O_(9)I_(3)/OVs could achieve a faster electron transport between Fe-O,facilitating Fe site acquire more electron.Consequently,the Fe-Bi/Bi_(7)O_(9)I_(3)/OVs in HE-VL-PEF process presented performance superiorities including excellent pollutant removal(91.91%),low electric energy consumption of 66.34 k Wh/kg total organic carbon(TOC),excellent reusability and wide p H adaptability(3–9).
文摘The microstructure, dielectric properties and chemical state of Ti element on BaTi_4O_9 (f)/(0.64 BaTi_4O_9-0.36BaPr_2Ti_4O_(12)) composites sample surface were characterized by X-ray diffraction (XRD), Transmission electron microscopy (TEM), LCR meter method and X-ray photoelectron spectroscopy (XPS). The results show that the system is composed of BaTi_4O_9 and BaPr_2Ti_4O_(12) two phases. Pr ions are distributed in the BaWi_4O_9 grains and the segregation of Pr ions was observed on the grain boundaries of BaTi_4O_9/BaTi_4O_9. The content of Ti^(3+) and Ti^(2+) decrease in the BPT system composites due to the addition of BaTi_4O_9 fibers, which improved the dielectric properties of the system. BPT10 sample with 10% BaTi_4O_9 fibers, has the best dielectric properties in the system, its ε_r = 64, tan δ= 1×10^(-4)(at 1 MHz) , and it may be a potential candidate for microwave dielectric ceramics.
基金This work sponsored by Motorola SPS Digital DNA Laboratories. It is also supported by a grant for State Key Program for Basic Research of China. We would like to thank Dr. Peir Y. Chu of Motorola SPS for his great help, useful advice and discussion.
文摘The hysteresis loop changes of ferroelecric SrBi_2 Ta_2 O_9 (SBT) thin films(330nm) us the temperature of forming gas (5 percent hydrogen+95 percent nitrogen) annealing weremeasured when the annealing time was 1min and 10min. The selected annealing temperature was at 100deg C,200 deg C 250 deg C, 300 deg C, 350 deg C,400 deg C and 450 deg C, respectively. Our resultsshowed that the ferroelectric properties were easily destroyed and the leakage current changedabruptly when the SBT thin films were in their ferroelectric phase (<270 deg C). The space chargesat the grain boundary may take an important role' in absorption polarity molecular hydrogen when theSBT thin films were in the ferroelectric phase. The oxygen recovery experiments were also performedand investigated in this work.
文摘Preparation of homogeneous Ca_ 3-xLa_xCo_4O_9 (x=0～0.4) single-phase ceramic powders was described using a tartrate complex method. The results show Ca3Co_4O_9 phase can be obtained by calcining the dry gel at 750 ℃ for 5 h. The Ca_ 3-xLa_xCo_4O_9 ceramics have been prepared by spark plasma sintering at 800 ℃ for 5 min. Spark plasma sintering process is effective in synthesis of Ca_ 3-xLa_xCo_4O_9 compact ceramics. The thermal conductivity of Ca_ 3-xLa_xCo_4O_9 bulks was investigated from room temperature to 700 ℃. The results show that Ca_ 2.7La_ 0.3Co_4O_9 has lowest thermal conductivity due to the increasing of phonon scattering by La substitution.
文摘Bismuth ferrite（Bi_2Fe_4O_9） thin films were grown on p-type Si（100） substrate by radio-frequency magnetron sputtering at 873 K. X-ray diffraction, field emission scanning electron microscopy and Raman spectroscopy studies revealed that the grown films have single-phase polycrystalline nature and are crystallized in orthorhombic structure. The grain size of the grown thin films was found to increase（56–130 nm） with sputtering power. Atomic force microscopy images clearly illustrated that the grown thin films have smooth surface. Energy-dispersive X-ray analysis revealed the presence of Bi, Fe and O elements with desired ratio and also the absence of impurities in the grown films. Analysis of ferroelectric hysteresis loops revealed that the remanent polarization and coercive field increase with the increase in sputtering power. Vicker＇s hardness analysis showed that the hardness of films strongly depends on the grain size and film thickness, which are mainly determined by the sputtering power. The above observations revealed that Bi_2Fe_4O_9 thin film deposited at higher sputtering power has good crystallinity and shows better electrical properties.
基金Project supported by National Natural Science Foundation of China(50604002)
文摘Single-phase La_（2–x）Nd_xMo_2O_9（0≤x≤1.8） compounds were prepared using solid-state reaction technique. Their structural and thermal p roperties were characterized by room and high temperatures X-ray diffraction（XRD）, thermo gravimetric analysis-differential scanningcalorimetry（TG-DSC）, and high temperature Raman spectra. The transport properties were investigated using D.C. four-probe technique and Hebb-Wagner polarization method. The substitution limit of Nb^（3＋） in La_（2–x）Nd_xMo_2O_9 was determined to be in the range of 1.8
文摘Dyeing wastewater poses a serious threat to environmental protection and industrial development.The piezoelectric effect can be used to optimize the band structure of semiconductors and improve the photon efficiency of photocatalysts.Bi_(2)Fe_(4)O_(9),a narrow gap semiconductor with piezoelectric effect,was prepared by a hydrothermal synthesis method for the degradation of reactive dye KN-R.The results show that the degradation efficiency of KN-R can be significantly improved by piezo-photocatalysis,and the degradation rate constant of piezo-photocatalysis k_(pi-ph)is about 3.4 times as large as the degradation rate constant of piezoelectric catalysis k_(pi)and about 2.6 times as large as the degradation rate constant of photocatalysis k_(ph).At a pH value of 3 and a lower KN-R mass concentration(60 mg/L),a higher degradation efficiency(98.5%)is achieved.CO_(3)^(2-)and cationic surfactant(CTAB)inhibit the degradation of KN-R.It is proved that the contributions of different active species to the degradation of KN-R follow the order:·OH,·O_(2)^(-),h^(+),and^(1)O_(2).The possible mechanism of piezo-photocatalytic degradation of KN-R was discussed.The photoexcitation generates a large amount of free charges,and the piezoelectric effect modulates the energy band structure of Bi_(2)Fe_(4)O_(9)and promotes the separation of photogenerated electron-hole pairs.The synergistic effect of the two factors significantly improves the degradation efficiency of KN-R.
基金funded by the National Natural Science Foundation of China(22272057)Natural Science Foundation of Guangdong Province(2019A1515012129)Science and Technology Planning Project of Guangzhou City(202002030420).
文摘Piezo-photocatalysis is an emerging photocatalytic technology in which the piezoelectric electric field drives photogenerated carriers to separate,thereby improving the photocatalytic activity of the catalyst.Herein,solid phase and one-step molten salt processes were used to prepare SrBi_(2)Nb_(2)O_(9)(SBN)powders with granular and sheet morphologies,respectively.The influence of micromorphology on the piezo-photocatalytic performances of SBN was determined by degrading ciprofloxacin hydrochloride(CIP).SBN nanosheets demonstrate remarkable piezo-photocatalytic performance,achieving an 89.13%CIP degradation rate in 60 min and an apparent rate constant of 34.73×10^(-3) min^(-1).This performance is approximately 2.65 times higher than that of granular SBN and outperformed many recently reported piezo-photocatalysts under similar experimental conditions.Free radical trapping techniques,electron spin resonance spectroscopy and liquid chromatography-mass spectrometry are utilized to study the potential paths and mechanisms of CIP degradation.Piezoresponse force microscopy and finite element simulation show that the piezo-response of SBN nanosheets is significantly higher than that of granular SBN.SBN nanosheets achieve high degradation efficiency due to their optimized conduction band positions and enhanced piezoelectric effect,facilitated by the two-dimensional nanosheet structures.In this work,the piezoelectric internal electric field of piezoelectric catalysts can be increased by tuning the catalyst morphology,which points to a possible direction for the production of high-performance piezoelectric catalysts.
基金financially supported by the Natural Science Foundation of China(NSFC,No.22165032)Beijing Natural Science Foundation(No.2242032)
文摘The rational design of composition and microstructure is a proven strategy for developing multifunctional high-performance electromagnetic wave(EMW)absorbers.In this study,a sandwich-structured multilayer nanoplate-like Bi_(2)Fe_(4)O_(9)@Polypyrrole(BFO@PPy)heterostructure was successfully designed and fabricated using an efficient microwave hydrothermal method and an in situ polymerization process.Specifically,Bi_(2)Fe_(4)O_(9)enhances the chemical activity of ammonium persulfate,which in turn initiates the polymerization of pyrrole monomers,resulting in the formation of BFO@PPy heterostructures.The thickness of the PPy coating layer in the BFO@PPy composite can be precisely controlled at the nanoscale,optimizing electromagnetic parameters,conduction losses and interface polarization loss.The fabricated BFO@PPy composite achieves a minimum reflection loss(RL_(min))of-57.8 dB at a thickness of 2.5 mm and an effective absorption bandwidth(EAB)of 6.96 GHz.Furthermore,the EMW absorption performance and mechanism were systematically validated through theoretical calculations,radar cross-sectional simulations(RCS),and first-principles analysis.Notably,the RCS simulation of a 1:1 scale F-22 Raptor fighter model provides a realistic evaluation of the composite's EMW absorption potential in military applications.The efficient fabrication method and superior electromagnetic absorption performance make BFO@PPy a promising candidate for use in complex electromagnetic environments and military domains.Additionally,the BFO@PPy composite exhibits rapid electrothermal conversion at a low voltage(3V),achieving active infrared camouflage within a controllable temperature range,further highlighting its multifunctional properties.
基金supported by the Natural Science Foundation of Gansu Province of China(Grant No.24JRRA171)the Postgraduate“Innovative Star”Project of Gansu Provincial Department of Education(Grant No.2025CXZX-587)the National Natural Science Foundation of China(Grant No.52162040)。
文摘Bi_(2)Fe_(4)O_(9) nanosheets were prepared using a hydrothermal method,followed by the introduction of NaBH_(4) and hightemperature calcination,which successfully induced strong ferromagnetism in the material at room temperature(M_(S)=10.22 emu/g and M_(r)=2.93 emu/g).This work demonstrates for the first time that Bi_(2)Fe_(4)O_(9) can exhibit such strong ferromagnetism at room temperature,with potential for further enhancements.Meanwhile,the ferroelectric properties of the samples were investigated.X-ray diffraction confirmed that the samples were single-phase with no detectable impurities.Based on a series of characterization analyses,it is inferred that Bi vacancies contribute to the observed strong magnetism.
基金National Key Research and Development Program of China (No. 2022YFB3807404)State Key Laboratory of Powder Metallurgy, the National Natural Science Foundation of China (No. 52102150, 52302158)Xiaomi Young Talents Program, China。
文摘MnO_(2)-doped Ca_(0.97)Bi_(2.03)Nb_(2)O_(9) ceramics with greatly improved piezoelectric performance were prepared via conventional solid state sintering method.The effects of MnO_(2) doping on the microstructure and electrical properties of Ca_(0.97)Bi_(2.03)Nb_(2)O_(9) ceramics were studied.X-ray diffraction(XRD)analysis and Rietveld refinement revealed a reduction in orthorhombicity with MnO_(2) doping,which contributed to the enhancement of the piezoelectric properties.Furthermore,the introduction of MnO_(2) lowered the sintering temperature,thereby reducing the formation of oxygen vacancies in the ceramic.The optimal performance was achieved in the Ca_(0.97)Bi_(2.03)Nb_(2)O_(9)−0.3wt.%MnO_(2) sample,exhibiting a piezoelectric coefficient(d33)of 13.6 pC/N,a DC resistivity of 3×10^(6)Ω·cm at 500℃,and a Curie temperature of 965℃.Additionally,all doped samples demonstrated excellent thermal stability over a wide temperature range,from room temperature to 900℃.
基金supported by the National Natural Science Foundation of China(12164034)the Natural Science Foundation of Inner Mongolia(2023LHMS01002)the Science and Technology Project of Shenzhen(JCYJ20220531102603007)。
文摘The gallate salts are frequently employed as matrix for mechanoluminescence(ML)materials largely due to their plentiful defect energy levels and robust piezoelectric characteristics.Nevertheless,the ML performance of specific gallate materials is inferior to that of sulfides and fluorides and thus requires improvement.To address this issue,it is essential to engineer appropriate lattice defects in order to facilitate the advancement of new elastic ML materials.Therefore,in the present study,a series of Ca_(3)Ga_(4)O_(9):0.01 Bi^(3+),xTb^(3+)(x=0.01,0.02,0.03,0.04,0.05 and 0.06)was synthesized using the traditional high-temperature solid-state method.Furthermore,a non-intrinsic defect control strategy utilising Bi^(3+)ions is presented,which serves to enhance the performance of calcium gallate.The ML intensity is enhanced by 112%in comparison to the undoped samples(concentration of Tb^(3+)is 0.04),resulting in an improved linearity between mechanical loading and ML intensity,along with the achievement of dualmode photoluminescence(PL).By analysing the crystal structure,PL,ML,and thermoluminescence(TL)properties of Ca_(3)Ga_(4)O_(9):Bi^(3+),Tb^(3+)(CGO:Bi^(3+),Tb^(3+)),coupled with the first principles calculations using density functional theory(DFT),the ML mechanism of CGO:Bi^(3+),Tb^(3+)was elucidated.This leads to the development of a versatile anti-counterfeiting device with both flexible and rigid multi-mode capabilities.
基金supported by the Natural Science Foundation of Xinjiang Uygur Autonomous Region(2021D01A03)Key Research and Development Projects of Xinjiang Uygur Autonomous Region(2022B02038)+1 种基金Special Training Program for Scientific and Technological Talents of Ethnic Minorities in Xinjiang Uygur Autonomous Region(2020D03025)Project of Tian chi talent leader in Xinjiang Uygur Autonomous Region(2022).
文摘Photocatalytic hydrogen evolution is of great importance with the proceeding of dual carbon goals,for inorganic catalysts have been explored with high efficiency.The structure and properties of oxide composites might take advantage of each compound and display an increased activity.In our previous study,boron doped-Cu_(3)NiBaTi_(4)O_(9)possessed a porous structure and its photocurrent response was apparent.To further verify its excellent catalytic activity,Al_(2)O_(3),and SiO_(2) were selected to replace with BaTi_(4)O_(9)to prepare different composites.The physical and chemical features of each sample were characterized with SEM,XRD,XPS,etc.to reveal their structural variations.Correspondingly,the H_(2)evolution rate was investigated with gas chromatography under the sunlight irritation.A distinct hydrogen yield was recorded with prepared samples.Further,the projected density of states analysis was taken through density functional theory calculations to appreciate the conduction band of the composite.The offered electrons during the photocatalytic process and the potential applicability of composites in the field of photocatalysis was verified.
