A series of Eu3＋ and Dy3＋ doped/co-doped as well as un-doped BaB2Si2Os phosphors were synthesized via solid state reaction method. The PL result showed typical blue and green emission from Dy3＋ and red emission fro...A series of Eu3＋ and Dy3＋ doped/co-doped as well as un-doped BaB2Si2Os phosphors were synthesized via solid state reaction method. The PL result showed typical blue and green emission from Dy3＋ and red emission from Eu3＋. The f-f transitions in- volving the lanthanide ions along with dopant site occupancy were discussed thoroughly. Phonon assisted energy transfer process was observed from Eu3＋ to Dy3＋, which enhanced the emissions of Dy3＋. Combinations of the emissions from Eu3＋ and Dy3＋ showed a possible white to red tuneable emission on the CIE diagram. The white warmth emissions of the phosphor were revealed to be ad- justable through designing the dopant concentration and excitation wavelengths. An unusual energy transfer that originated from Eu3＋ to Dy3＋ was also discovered and the energy transfer mechanism was discussed. Proposed energy transfer mechanism was investigated using luminescence decay lifetime. All the phosphor exhibited efficient excitation in the UV range which matched well with the emissions from GaN-based LED chips. This presented the BaB2Si208 phosphor as a promising candidate for white LED applications. The effects of doping on the structural properties and the optical band gap of BaB2Si208 phosphor were also discussed in this study.展开更多
Rare earth(Ⅲ)diphenyl-4-amine sulfonates(RE(DAS)3·xH2O,RE=Eu^3+,Tb^3+)phosphors were synthesized by precursor method from barium diphenyl-4-amine sulfonate and rare earth sulfates.FTIR,TG/DSC coupled to mass spe...Rare earth(Ⅲ)diphenyl-4-amine sulfonates(RE(DAS)3·xH2O,RE=Eu^3+,Tb^3+)phosphors were synthesized by precursor method from barium diphenyl-4-amine sulfonate and rare earth sulfates.FTIR,TG/DSC coupled to mass spectrometry(TG/DSC/MS),X-ray powder diffraction(XPD),scanning electron microscopy(SEM)and photo luminesce nce(PL)spectroscopy were utilized to structurally and morphologically characterize the samples.Thermal decomposition of Eu(DAS)3·7H2O and Tb(DAS)3·2H2O at 973 K under dynamic air atmosphere results in crystalline Eu2O2SO4 and Tb2O2SO4 materials,respectively.Accordingly,MS spectra reveal the liberation of thermal decomposition products of precursors,largely as CO2,NO2 and SO2 gases.The diphenyl-4-amine sulfonate(DAS)ligand demonstrats a good stabilizing property for Eu^3+and Tb^3+ions.The Eu(DAS)3·7H2O and Tb(DAS)3·2H2O compounds display efficient red and green emissions,under UV excitation,arising from the 5D0→7FJ(J=0-4)and 5D4→7FJ(J=0-6)transitions of the Eu^3+and Tb^3+ions,respectively.展开更多
In this paper, we investigate the Raman and photoluminescence spectra of Y_2O_3/Eu^（3＋） and Y_2O_3/Eu^（3＋）/Mg^（2＋） nanorods under high pressures using 514-nm and 532-nm laser light excitation. We observe tran...In this paper, we investigate the Raman and photoluminescence spectra of Y_2O_3/Eu^（3＋） and Y_2O_3/Eu^（3＋）/Mg^（2＋） nanorods under high pressures using 514-nm and 532-nm laser light excitation. We observe transitions from the initial cubic phase to amorphous at pressures higher than 24 GPa for both Y_2O_3/Eu^（3＋） and Y_2O_3/Eu^（3＋）/Mg^（2＋） nanorods. In addition, Y_2O_3/Eu^（3＋） and Y_2O_3/Eu^（3＋）/Mg^（2＋） nanorods exhibit different distorted states after the pressure has been raised to 8 GPa. The analyses of intensity ratios, I_（0-2）/I_（0-1） from ~5D_（0–）~7F2_to^5D_（0–）~7F_1and I_（0-2）A/B of ~5D_（0–）7F_2 transitions indicate that Y_2O_3/Eu^（3＋）/Mg^（2＋） nanorods exhibit stronger local micro-surrounding characteristics for Eu^（3＋） ions in a pressuremodulated crystal field. The doped Mg2＋ion results in reducing the crystal ionicity in the distorted lattice state under high pressures. The use of doped ions as an ion modifier can be applied to the study of small local microstructural changes through Eu^（3＋） luminescence.展开更多
The reduction of carbon emissions in the steel industry is a significant challenge,and utilizing CO_(2) from carbon intensive steel industry off-gases for methanol production is a promising strategy for decarbonizatio...The reduction of carbon emissions in the steel industry is a significant challenge,and utilizing CO_(2) from carbon intensive steel industry off-gases for methanol production is a promising strategy for decarbonization.However,steelwork off-gases typically contain various impurities,including H_(2)S,which can deactivate commercial methanol synthesis catalysts,Cu/ZnO/Al_(2)O_(3)(CZA).Reverse water-gas shift(RWGS)reaction is the predominant side reaction in CO_(2) hydrogenation to methanol which can occur at ambient pressure,enabling the decouple of RWGS from methanol production at high pressure.Then,a series of activated CZA catalysts has been in-situ pretreated in 400 ppm H_(2)S/Ar at 250℃and tested for both RWGS reaction at ambient pressure and CO_(2) hydrogenation to methanol at high pressure.An innovative decoupling strategy was employed to isolate the RWGS reaction from the methanol synthesis process,enabling the investigation of the evolution of active site structures and the poisoning mechanism through elemental analysis,X-ray Diffraction,X-ray Photoelectron Spectroscopy,Fourier Transform Infrared Spectroscopy,Temperature Programmed Reduction and CO_(2) Temperature Programmed Desorption.The results indicate that there are different dynamic migration behaviors of ZnO_(x) in the two reaction systems,leading to different poisoning mechanisms.These interesting findings are beneficial to develop sulfur resistant and durable highly efficient catalysts for CO_(2) hydrogenation to methanol,promoting the carbon emission reduction in steel industry.展开更多
Developing efficient photocatalysts for CO_(2)conversion under full-spectrum irradiation remains a key challenge for solar-to-chemical energy conversion.In this study,a novel S-scheme heterojunction composed of reduct...Developing efficient photocatalysts for CO_(2)conversion under full-spectrum irradiation remains a key challenge for solar-to-chemical energy conversion.In this study,a novel S-scheme heterojunction composed of reduction Cs_(0.32)WO_(3)(CWO)nanosheets with hexagonal structure and oxidation WO_(3)·2H_(2)O(WO)nanorods with monoclinic structure photocatalyst was successfully constructed via an ultrasound strategy.Under full-spectrum irradiation for 4 h,the optimized 2D/1D of heterostructure CWO/WO-0.8 exhibited superior photocatalytic performance,achieving CO and CH_(3)OH yields of 29.74 and 63.71μmol·g^(-1),respectively.The enhanced activity is primarily ascribed to the formation of an S-scheme charge transfer pathway,which facilitates efficient separation and directional migration of photogenerated charge carriers through the internal electric field at the CWO/WO interface.This process facilitates the electron enrichment on the CWO surface and significantly enhances its CO_(2)reduction ability.Besides,the results of various characterizations show that CWO/WO-0.8 possesses enhanced optical response capability.The results of density functional theory calculations and CO_(2)-temperature programmed desorption analysis confirmed that the CWO/WO heterojunction exhibits stronger CO_(2)adsorption and activation abilities compared to the pristine CWO and WO.The reaction pathway for CH_(3)OH production was elucidated by in-situ diffused reflectance Fourier transformed infrared tests.This work provides new insights into the rational design of S-scheme photocatalysts for efficient and selective CO_(2)conversion.展开更多
基金supported by Fundamental Research Grant Scheme of Malaysia(J130000.2526.03H97)the National Natural Science Foundation of China(51372142)
文摘A series of Eu3＋ and Dy3＋ doped/co-doped as well as un-doped BaB2Si2Os phosphors were synthesized via solid state reaction method. The PL result showed typical blue and green emission from Dy3＋ and red emission from Eu3＋. The f-f transitions in- volving the lanthanide ions along with dopant site occupancy were discussed thoroughly. Phonon assisted energy transfer process was observed from Eu3＋ to Dy3＋, which enhanced the emissions of Dy3＋. Combinations of the emissions from Eu3＋ and Dy3＋ showed a possible white to red tuneable emission on the CIE diagram. The white warmth emissions of the phosphor were revealed to be ad- justable through designing the dopant concentration and excitation wavelengths. An unusual energy transfer that originated from Eu3＋ to Dy3＋ was also discovered and the energy transfer mechanism was discussed. Proposed energy transfer mechanism was investigated using luminescence decay lifetime. All the phosphor exhibited efficient excitation in the UV range which matched well with the emissions from GaN-based LED chips. This presented the BaB2Si208 phosphor as a promising candidate for white LED applications. The effects of doping on the structural properties and the optical band gap of BaB2Si208 phosphor were also discussed in this study.
基金Project supported by Higher Education Personnel Improvement Coordination(CAPES),Laboratory of Thermal Analysis Prof.Ivo Giolito(LATIG-USP),Laboratory of f-block Elements(Leb-f)USP,Petroleum Nucleus(LABPETRO-UFES)of Federal University of Espirito Santo,Institute of Low Temperature and Structure Research and the Polish Academy of Sciences
文摘Rare earth(Ⅲ)diphenyl-4-amine sulfonates(RE(DAS)3·xH2O,RE=Eu^3+,Tb^3+)phosphors were synthesized by precursor method from barium diphenyl-4-amine sulfonate and rare earth sulfates.FTIR,TG/DSC coupled to mass spectrometry(TG/DSC/MS),X-ray powder diffraction(XPD),scanning electron microscopy(SEM)and photo luminesce nce(PL)spectroscopy were utilized to structurally and morphologically characterize the samples.Thermal decomposition of Eu(DAS)3·7H2O and Tb(DAS)3·2H2O at 973 K under dynamic air atmosphere results in crystalline Eu2O2SO4 and Tb2O2SO4 materials,respectively.Accordingly,MS spectra reveal the liberation of thermal decomposition products of precursors,largely as CO2,NO2 and SO2 gases.The diphenyl-4-amine sulfonate(DAS)ligand demonstrats a good stabilizing property for Eu^3+and Tb^3+ions.The Eu(DAS)3·7H2O and Tb(DAS)3·2H2O compounds display efficient red and green emissions,under UV excitation,arising from the 5D0→7FJ(J=0-4)and 5D4→7FJ(J=0-6)transitions of the Eu^3+and Tb^3+ions,respectively.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11304380,11404241,11275138,11604240,and 51320105007)the Program for Changjiang Scholars and Innovative Research Team in University,China(Grant No.IRT1132)
文摘In this paper, we investigate the Raman and photoluminescence spectra of Y_2O_3/Eu^（3＋） and Y_2O_3/Eu^（3＋）/Mg^（2＋） nanorods under high pressures using 514-nm and 532-nm laser light excitation. We observe transitions from the initial cubic phase to amorphous at pressures higher than 24 GPa for both Y_2O_3/Eu^（3＋） and Y_2O_3/Eu^（3＋）/Mg^（2＋） nanorods. In addition, Y_2O_3/Eu^（3＋） and Y_2O_3/Eu^（3＋）/Mg^（2＋） nanorods exhibit different distorted states after the pressure has been raised to 8 GPa. The analyses of intensity ratios, I_（0-2）/I_（0-1） from ~5D_（0–）~7F2_to^5D_（0–）~7F_1and I_（0-2）A/B of ~5D_（0–）7F_2 transitions indicate that Y_2O_3/Eu^（3＋）/Mg^（2＋） nanorods exhibit stronger local micro-surrounding characteristics for Eu^（3＋） ions in a pressuremodulated crystal field. The doped Mg2＋ion results in reducing the crystal ionicity in the distorted lattice state under high pressures. The use of doped ions as an ion modifier can be applied to the study of small local microstructural changes through Eu^（3＋） luminescence.
基金supported by the National Natural Science Foundation of China(Nos.22276060 and 21976059)Guangdong Basic and Applied Basic Research Foundation(No.2024A1515012636)China Scholarship Council Scholarship(No.201906155006)。
文摘The reduction of carbon emissions in the steel industry is a significant challenge,and utilizing CO_(2) from carbon intensive steel industry off-gases for methanol production is a promising strategy for decarbonization.However,steelwork off-gases typically contain various impurities,including H_(2)S,which can deactivate commercial methanol synthesis catalysts,Cu/ZnO/Al_(2)O_(3)(CZA).Reverse water-gas shift(RWGS)reaction is the predominant side reaction in CO_(2) hydrogenation to methanol which can occur at ambient pressure,enabling the decouple of RWGS from methanol production at high pressure.Then,a series of activated CZA catalysts has been in-situ pretreated in 400 ppm H_(2)S/Ar at 250℃and tested for both RWGS reaction at ambient pressure and CO_(2) hydrogenation to methanol at high pressure.An innovative decoupling strategy was employed to isolate the RWGS reaction from the methanol synthesis process,enabling the investigation of the evolution of active site structures and the poisoning mechanism through elemental analysis,X-ray Diffraction,X-ray Photoelectron Spectroscopy,Fourier Transform Infrared Spectroscopy,Temperature Programmed Reduction and CO_(2) Temperature Programmed Desorption.The results indicate that there are different dynamic migration behaviors of ZnO_(x) in the two reaction systems,leading to different poisoning mechanisms.These interesting findings are beneficial to develop sulfur resistant and durable highly efficient catalysts for CO_(2) hydrogenation to methanol,promoting the carbon emission reduction in steel industry.
文摘Developing efficient photocatalysts for CO_(2)conversion under full-spectrum irradiation remains a key challenge for solar-to-chemical energy conversion.In this study,a novel S-scheme heterojunction composed of reduction Cs_(0.32)WO_(3)(CWO)nanosheets with hexagonal structure and oxidation WO_(3)·2H_(2)O(WO)nanorods with monoclinic structure photocatalyst was successfully constructed via an ultrasound strategy.Under full-spectrum irradiation for 4 h,the optimized 2D/1D of heterostructure CWO/WO-0.8 exhibited superior photocatalytic performance,achieving CO and CH_(3)OH yields of 29.74 and 63.71μmol·g^(-1),respectively.The enhanced activity is primarily ascribed to the formation of an S-scheme charge transfer pathway,which facilitates efficient separation and directional migration of photogenerated charge carriers through the internal electric field at the CWO/WO interface.This process facilitates the electron enrichment on the CWO surface and significantly enhances its CO_(2)reduction ability.Besides,the results of various characterizations show that CWO/WO-0.8 possesses enhanced optical response capability.The results of density functional theory calculations and CO_(2)-temperature programmed desorption analysis confirmed that the CWO/WO heterojunction exhibits stronger CO_(2)adsorption and activation abilities compared to the pristine CWO and WO.The reaction pathway for CH_(3)OH production was elucidated by in-situ diffused reflectance Fourier transformed infrared tests.This work provides new insights into the rational design of S-scheme photocatalysts for efficient and selective CO_(2)conversion.
