A convenient,effcient and environmentally benign procedure has been developed for the synthesis of pyrano[4,3-b]pyran derivatives via a one-pot,three-component reaction of 4-hydroxy-6-methylpyran-2-one,aldehydes and m...A convenient,effcient and environmentally benign procedure has been developed for the synthesis of pyrano[4,3-b]pyran derivatives via a one-pot,three-component reaction of 4-hydroxy-6-methylpyran-2-one,aldehydes and malononitrile in water using H6P2W18O62á18H2O as catalyst.Reusability of the catalyst and reaction media,short reaction times and easy isolation of products are some added advantages of the present methodology.展开更多
In this paper,we developed low dose X-ray induced long afterglow phosphor Ca_(2)P_(2)O_(7):Pr^(3+),which shows excellent afterglow luminescence from ultraviolet C(UVC)to red region.The photoluminescent results show th...In this paper,we developed low dose X-ray induced long afterglow phosphor Ca_(2)P_(2)O_(7):Pr^(3+),which shows excellent afterglow luminescence from ultraviolet C(UVC)to red region.The photoluminescent results show that under 445.7 nm excitation,Ca_(1.995)P_(2)O_(7):0.5%Pr3+displays red emissions peaked at 598.3 and651.9 nm,corresponding to1D2-3H4and3P0-3F2transitions of Pr^(3+),respectively.Due to its pure red emission(CIE coordinates(0.59101,0.39926)),Ca_(1.995)P_(2)O_(7):0.5%Pr^(3+)can be regarded as a potential LED red phosphor.More importantly,Ca_(2)P_(2)O_(7):Pr^(3+)shows long afterglow luminescence from UVC to red region,which consists of four co ntinuous emissions with similar intensity including 260,359,466 and 598.3 nm.Since these afterglow continuous emissions are fitted to the absorption of most photodynamic therapy(PDT)agents,Ca_(2)P_(2)O_(7):Pr^(3+)can be regarded as excellent PDT agents.Furthermo re,30 s X-ray irradiation can induce 5400 s decay of Ca_(1.997)P_(2)O_(7):0.3%Pr^(3+),and its afterglow emission intensity still reaches 5×10^(4)cps after 5400 s decay.Even only 5 s X-ray irradiation also can produce 4.75×10^(4)cps afterglow emis sion after10 s decay.In addition,the repeat 980 nm laser irradiations can induce co ntinuous strong photo-stimulated(PSL)luminescent peaks,which can be utilized to conduct high efficiency PDT without another X-ray irradiation.The thermoluminesce nce results reveal that the existence of shallow(0.89 eV)and deep traps are responsible for the excellent X-ray induced long afterglow and PSL luminescence.All these results suggest that Ca_(2)P2O7:Pr^(3+)possesses great potential to be regarded as high efficiency PDT agents.展开更多
The phase composition and microstructure of alkaline vanadium slag were characterized using scanning electron microscopy and energy-dispersive X-ray spectroscopy(SEM-EDS)and X-ray diffraction(XRD).A crystallization mo...The phase composition and microstructure of alkaline vanadium slag were characterized using scanning electron microscopy and energy-dispersive X-ray spectroscopy(SEM-EDS)and X-ray diffraction(XRD).A crystallization model of spinel was established to calculate the effects of basicity(the mass ratio of CaO to SiO_(2))and P_(2)O_(5) on crystal growth rates and precipitation patterns.Based on the crystal size distribution(CSD)theory,the size distribution and growth mechanisms of spinel crystals in alkaline vanadium slag at different temperatures were investigated.The results revealed that,at a cooling rate of 5 K/min,the mean grain size of spinel increased from 12.77 to 21.52μm as the temperature decreased from 1748 to 1598 K,with spinel growth being controlled by the interface.At 1548 K,the spinel particle size reached 31.04μm,indicating a supply-controlled growth mechanism as the temperature decreased from 1598 to 1548 K.Increased P_(2)O_(5) content hindered the crystal growth,while an increase in basicity promoted nucleation and growth.Furthermore,MnCr_(2)O_(4) preferentially crystallized and grew in alkaline vanadium slag.展开更多
The synthesis of Ta-substituted polyoxometalates has always been an attractive but challenging goal.Three novel tantalum-containing 12-tungsto-2-phosphates were successfully prepared using the water bath method.The mo...The synthesis of Ta-substituted polyoxometalates has always been an attractive but challenging goal.Three novel tantalum-containing 12-tungsto-2-phosphates were successfully prepared using the water bath method.The monomer,K_(11)Li[P_(2)W_(12)(TaO_(2))_(6)O_(56)]·19H_(2)O(1),is composed of{P_(2)W_(12)}and 6{Ta(O_(2))}building blocks,similar to[P_(2)W_(12)(NbO_(2))_(6)O_(56)]^(12-).Monomer 1 polymerized to form two cis-trans dimers,K1_(3)Li_(6)H-cis-[P_(2)W_(12)Ta_(4)(TaO_(2))_(2)O_(59)]_(2)·61H_(2)O(2)and KNa_(3)Li_(4)H_(12)-trans-[P_(2)W_(12)Ta_(4)(TaO_(2))_(2)O_(59)]_(2)·37H_(2)O(3).Compounds 1-3 can serve as a structural motif to manufacture additional fascinating molecular clusters,promoting the advancement of POM chemistry.In contrast to[P_(2)W_(12)(NbO_(2))_(6)O_(56)]^(12-),compound 1 exhibits exceptional stability,evidenced by ESI-MS,IR,and NMR spectroscopy.In addition,2 and 3 exhibit high proton conductivity and superior water adsorption properties.展开更多
In this work,for the first time,it is demonstrated that during the insertion/extraction of Na ions,the structural evolution at the Na_(4)site at a voltage range of 3-4 V is a key factor for the capacity decay of Na_(4...In this work,for the first time,it is demonstrated that during the insertion/extraction of Na ions,the structural evolution at the Na_(4)site at a voltage range of 3-4 V is a key factor for the capacity decay of Na_(4)Fe_(3)(PO_(4))_(2)P_(2)O_(7)(NFPP).Herein,a strategy of introducing columnar potassium ions at the Na_(4)site is proposed to address the aforementioned challenge.As a cathode material for sodium-ion batteries,the K_(0.12)Na_(3.88)Fe_(3)(PO_(4))_(2)P_(2)O_(7)/C(K-NFPP)composite enhances the reversibility of Na_(4)extraction.Specifically,the K-NFPP exhibits an initial discharge capacity of 107.8 mAh g^(-1)at a high current density of 5 C,with a capacity retention of 91.4% after 2000 cycles,outperforming the pristine NFPP material(81.1 m Ah g^(-1)and 67.1%).At 5 C,the K-NFPP also retains 81.5% of the reversible capacity at 0.1 C,whereas the NFPP only retains 68.3%.Moreover,the K-NFPP-based full-cell delivers an initial capacity of 110.1 m Ah g^(-1)at 1 C,with a capacity retention of 90% after 100 cycles.It is found that in comparison to K-doping of the Na1,Na2,and Na3 sites,K-doping at the Na4 site effectively optimizes the band gap and stabilizes the crystal structure,thereby reducing lattice changes of FeO_(6)evolution during Na^(+)insertion/extraction.As a result,the introduction of columnar potassium ions significantly enhances the capacity contribution of the Na_(4)site,optimizes reaction kinetics,and effectively mitigates the capacity decay of NFPP cathodes.It is believed that this study offers a new entry point for the application of NFPP in high-voltage sodium storage.展开更多
文摘A convenient,effcient and environmentally benign procedure has been developed for the synthesis of pyrano[4,3-b]pyran derivatives via a one-pot,three-component reaction of 4-hydroxy-6-methylpyran-2-one,aldehydes and malononitrile in water using H6P2W18O62á18H2O as catalyst.Reusability of the catalyst and reaction media,short reaction times and easy isolation of products are some added advantages of the present methodology.
基金Project supported by the fund of"Two-Hundred Talent"plan of Yantai Citythe National Natural Science Foundation of China(11974013)+1 种基金Natural Science Foundation of Fujian Province(2022J011270)the State Key Research Project of Shandong Natural Science Foundation(ZR2020KB019)。
文摘In this paper,we developed low dose X-ray induced long afterglow phosphor Ca_(2)P_(2)O_(7):Pr^(3+),which shows excellent afterglow luminescence from ultraviolet C(UVC)to red region.The photoluminescent results show that under 445.7 nm excitation,Ca_(1.995)P_(2)O_(7):0.5%Pr3+displays red emissions peaked at 598.3 and651.9 nm,corresponding to1D2-3H4and3P0-3F2transitions of Pr^(3+),respectively.Due to its pure red emission(CIE coordinates(0.59101,0.39926)),Ca_(1.995)P_(2)O_(7):0.5%Pr^(3+)can be regarded as a potential LED red phosphor.More importantly,Ca_(2)P_(2)O_(7):Pr^(3+)shows long afterglow luminescence from UVC to red region,which consists of four co ntinuous emissions with similar intensity including 260,359,466 and 598.3 nm.Since these afterglow continuous emissions are fitted to the absorption of most photodynamic therapy(PDT)agents,Ca_(2)P_(2)O_(7):Pr^(3+)can be regarded as excellent PDT agents.Furthermo re,30 s X-ray irradiation can induce 5400 s decay of Ca_(1.997)P_(2)O_(7):0.3%Pr^(3+),and its afterglow emission intensity still reaches 5×10^(4)cps after 5400 s decay.Even only 5 s X-ray irradiation also can produce 4.75×10^(4)cps afterglow emis sion after10 s decay.In addition,the repeat 980 nm laser irradiations can induce co ntinuous strong photo-stimulated(PSL)luminescent peaks,which can be utilized to conduct high efficiency PDT without another X-ray irradiation.The thermoluminesce nce results reveal that the existence of shallow(0.89 eV)and deep traps are responsible for the excellent X-ray induced long afterglow and PSL luminescence.All these results suggest that Ca_(2)P2O7:Pr^(3+)possesses great potential to be regarded as high efficiency PDT agents.
基金supported by the National Natural Science Foundation of China(No.51974047)the Natural Science Foundation of Chongqing,China(No.cstc2022ycjh-bgzxm0003)the Large Instrument Foundation of Chongqing University,China(No.202303150239)。
文摘The phase composition and microstructure of alkaline vanadium slag were characterized using scanning electron microscopy and energy-dispersive X-ray spectroscopy(SEM-EDS)and X-ray diffraction(XRD).A crystallization model of spinel was established to calculate the effects of basicity(the mass ratio of CaO to SiO_(2))and P_(2)O_(5) on crystal growth rates and precipitation patterns.Based on the crystal size distribution(CSD)theory,the size distribution and growth mechanisms of spinel crystals in alkaline vanadium slag at different temperatures were investigated.The results revealed that,at a cooling rate of 5 K/min,the mean grain size of spinel increased from 12.77 to 21.52μm as the temperature decreased from 1748 to 1598 K,with spinel growth being controlled by the interface.At 1548 K,the spinel particle size reached 31.04μm,indicating a supply-controlled growth mechanism as the temperature decreased from 1598 to 1548 K.Increased P_(2)O_(5) content hindered the crystal growth,while an increase in basicity promoted nucleation and growth.Furthermore,MnCr_(2)O_(4) preferentially crystallized and grew in alkaline vanadium slag.
基金supported by the National Natural Science Foundation of China(Nos.22071044,21771054 and 22171071)。
文摘The synthesis of Ta-substituted polyoxometalates has always been an attractive but challenging goal.Three novel tantalum-containing 12-tungsto-2-phosphates were successfully prepared using the water bath method.The monomer,K_(11)Li[P_(2)W_(12)(TaO_(2))_(6)O_(56)]·19H_(2)O(1),is composed of{P_(2)W_(12)}and 6{Ta(O_(2))}building blocks,similar to[P_(2)W_(12)(NbO_(2))_(6)O_(56)]^(12-).Monomer 1 polymerized to form two cis-trans dimers,K1_(3)Li_(6)H-cis-[P_(2)W_(12)Ta_(4)(TaO_(2))_(2)O_(59)]_(2)·61H_(2)O(2)and KNa_(3)Li_(4)H_(12)-trans-[P_(2)W_(12)Ta_(4)(TaO_(2))_(2)O_(59)]_(2)·37H_(2)O(3).Compounds 1-3 can serve as a structural motif to manufacture additional fascinating molecular clusters,promoting the advancement of POM chemistry.In contrast to[P_(2)W_(12)(NbO_(2))_(6)O_(56)]^(12-),compound 1 exhibits exceptional stability,evidenced by ESI-MS,IR,and NMR spectroscopy.In addition,2 and 3 exhibit high proton conductivity and superior water adsorption properties.
基金financial support from the National Natural Science Foundation of China(52272237,22279101 and 22172117)the Natural Science Foundation of Shaanxi(2020JC-41 and 2024JC-YBQN-0141)+2 种基金the Scientific Research Program Funded by the Education Department of Shaanxi Provincial Government(22JP056)the S&T Program of Energy Shaanxi Laboratory(ESLB202402)the Foshan Science and Technology Innovation Team Project(1920001004098)。
文摘In this work,for the first time,it is demonstrated that during the insertion/extraction of Na ions,the structural evolution at the Na_(4)site at a voltage range of 3-4 V is a key factor for the capacity decay of Na_(4)Fe_(3)(PO_(4))_(2)P_(2)O_(7)(NFPP).Herein,a strategy of introducing columnar potassium ions at the Na_(4)site is proposed to address the aforementioned challenge.As a cathode material for sodium-ion batteries,the K_(0.12)Na_(3.88)Fe_(3)(PO_(4))_(2)P_(2)O_(7)/C(K-NFPP)composite enhances the reversibility of Na_(4)extraction.Specifically,the K-NFPP exhibits an initial discharge capacity of 107.8 mAh g^(-1)at a high current density of 5 C,with a capacity retention of 91.4% after 2000 cycles,outperforming the pristine NFPP material(81.1 m Ah g^(-1)and 67.1%).At 5 C,the K-NFPP also retains 81.5% of the reversible capacity at 0.1 C,whereas the NFPP only retains 68.3%.Moreover,the K-NFPP-based full-cell delivers an initial capacity of 110.1 m Ah g^(-1)at 1 C,with a capacity retention of 90% after 100 cycles.It is found that in comparison to K-doping of the Na1,Na2,and Na3 sites,K-doping at the Na4 site effectively optimizes the band gap and stabilizes the crystal structure,thereby reducing lattice changes of FeO_(6)evolution during Na^(+)insertion/extraction.As a result,the introduction of columnar potassium ions significantly enhances the capacity contribution of the Na_(4)site,optimizes reaction kinetics,and effectively mitigates the capacity decay of NFPP cathodes.It is believed that this study offers a new entry point for the application of NFPP in high-voltage sodium storage.
