In a rotary kiln process for phosphoric acid production,the reaction between gaseous phosphorus pentoxide（P2O5）and phosphate ore and silica contained in feed balls（the so-called P2O5＂absorption＂）not only reduces...In a rotary kiln process for phosphoric acid production,the reaction between gaseous phosphorus pentoxide（P2O5）and phosphate ore and silica contained in feed balls（the so-called P2O5＂absorption＂）not only reduces phosphorous recovery but also generates a large amount of low melting-point side products.The products may give rise to formation of kiln ring,which interferes with kiln operation performance.In this study,the reactions of gaseous P2O5with solid calcium phosphate（Ca3（PO4）2）,silica（SiO2）and their mixture,respectively,were investigated via combined chemical analysis and various characterizations comprised of X-ray diffraction（XRD）,Fourier-transform infrared（FT-IR）spectroscopy,thermogravimetric analysis and differential scanning calorimeter（TG＆DSC）,and scanning electron microscopy and energy dispersive spectrometer（SEM＆EDS）.Attentions were focused on apparent morphology,phase transformation and thermal stability of the products of the P2O5＂absorption＂at different temperatures.The results show that the temperature significantly affected the＂absorption＂.The reaction between pure Ca3（PO4）2 and P2O5 occurred at 500℃.Calcium metaphosphate（Ca（PO3）2）was the primary product at the temperatures≤900℃ with its melting point≤900℃ while calcium pyrophosphate（Ca2P2O7）was obtained over 1000℃,which has a melting point≤1200℃.The＂absorption＂by pure SiO2 started at 800℃ and the most significant reaction occurred at 1000℃ with formation of silicon pyrophosphate（SiP2O7）product of melting point≤1000℃.Using mixed Ca3（PO4）2and SiO2as raw material,the＂absorption＂by Ca3（PO4）2 was enhanced due to existence of silica.At 600–700℃,silica was inert to P2O5and thus formed a porous structure in the raw material,which accelerated diffusion of gaseous P2O5inside the mixture.At higher temperatures,the combined＂absorption＂by calcium phosphate and reaction between silicon dioxide and the＂absorption＂product calcium pyrophosphate,reinforced the＂absorption＂by the mixture.Besides,it was found that both Ca（PO3）2and SiP2O7were unstable at high temperatures and would decompose to Ca2P2O7and SiO2,respectively,at over 1000℃ and 1100℃ with the release of gaseous P2O5at the same time.展开更多
In this study,a single-doped phosphors yttrium aluminum garnet(Y_(3)Al_(5)O_(12),YAG):Ce^(3+),single-doped YAG:Sc^(3+),and double-doped phosphors YAG:Ce^(3+),Sc^(3+) were prepared by spark plasma sintering(SPS)(lower ...In this study,a single-doped phosphors yttrium aluminum garnet(Y_(3)Al_(5)O_(12),YAG):Ce^(3+),single-doped YAG:Sc^(3+),and double-doped phosphors YAG:Ce^(3+),Sc^(3+) were prepared by spark plasma sintering(SPS)(lower than 1 200℃).The characteristics of synthesized phosphors were determined using scanning electron microscopy(SEM),X-ray diffraction(XRD),and fluorescence spectroscopy.During SPS,the lattice structure of YAG was maintained by the added Ce^(3+) and Sc^(3+).The emission wavelength of YAG:Ce^(3+) prepared from SPS(425-700 nm) was wider compared to that of YAG:Ce^(3+) prepared from high-temperature solid-state reaction(HSSR)(500-700 nm).The incorporation of low-dose Sc^(3+) in YAG:Ce^(3+) moved the emission peak towards the short wavelength.展开更多
One of the primary challenges in relation to phosphoric acid fuel cells is catalyst poisoning by phosphate anions that occurs at the interface between metal nanoparticles and the electrolyte.The strong adsorption of p...One of the primary challenges in relation to phosphoric acid fuel cells is catalyst poisoning by phosphate anions that occurs at the interface between metal nanoparticles and the electrolyte.The strong adsorption of phosphate anions on the catalyst surface limits the active sites for the oxygen reduction reaction(ORR),significantly deteriorating fuel cell performance.Here,antipoisoning catalysts consisting of Pt-based nanoparticles encapsulated in an ultrathin carbon shell that can be used as a molecular sieve layer are rationally designed.The pore structure of the carbon shells is systematically regulated at the atomic level by high-temperature gas treatment,allowing O_(2) molecules to selectively react on the active sites of the metal nanoparticles through the molecular sieves.Besides,the carbon shell,as a protective layer,effectively prevents metal dissolution from the catalyst during a long-term operation.Consequently,the defect-controlled carbon shell leads to outstanding ORR activity and durability of the hybrid catalyst even in phosphoric acid electrolytes.展开更多
Electrochemical N_(2) reduction reaction(eNRR) over Cu-based catalysts suffers from an intrinsically low activity of Cu for activation of stable N_(2) molecules and the limited supply of N_(2) to the catalyst due to i...Electrochemical N_(2) reduction reaction(eNRR) over Cu-based catalysts suffers from an intrinsically low activity of Cu for activation of stable N_(2) molecules and the limited supply of N_(2) to the catalyst due to its low solubility in aqueous electrolytes.Herein,we propose phosphorus-activated Cu electrocatalysts to generate electron-deficient Cu sites on the catalyst surface to promote the adsorption of N_(2) molecules.The eNRR system is further modified using a gas diffusion electrode(GDE) coated with polytetrafluoroethylene(PTFE) to form an effective three-phase boundary of liquid water-gas N_(2)-solid catalyst to facilitate easy access of N_(2) to the catalytic sites.As a result,the new catalyst in the flow-type cell records a Faradaic efficiency of 13.15% and an NH_(3) production rate of 7.69 μg h^(-1) cm^(-2) at-0.2 V_(RHE),which represent 3.56 and 59.2 times increases from those obtained with a pristine Cu electrode in a typical electrolytic cell.This work represents a successful demonstration of dual modification strategies;catalyst modification and N_(2) supplying system engineering,and the results would provide a useful platform for further developments of electrocatalysts and reaction systems.展开更多
It is still a lack of bifunctional catalysts for ammonia oxidation reaction(AOR)and hydrogen evolution reaction(HER)due to their different reaction mechanisms.In this work,P is doped into PtZn alloy by calcination wit...It is still a lack of bifunctional catalysts for ammonia oxidation reaction(AOR)and hydrogen evolution reaction(HER)due to their different reaction mechanisms.In this work,P is doped into PtZn alloy by calcination with NaH_(2)PO_(2) as P source to induce the lattice tensile strain of Pt and the electronic interaction between P and Zn,which optimizes the AOR and HER activity simultaneously.The sample with the optimal P content can drive the AOR peak current density of 293.6 mA·mgPt^(-1),which is almost 2.7 times of Pt.For HER,the overpotential at^(-1)0 mA·cm^(-2) is only 23 mV with Tafel slope of 34.1 mV·dec^(-1).Furthermore,only 0.59 V is needed to obtain 50 mA·mgPt^(-1) for ammonia electrolysis under a two-electrode system.Therefore,this work shows an ingenious method to design bifunctional catalysts for ammonia electrolysis.展开更多
Blended cement containing blast furnace slag (BFS) and phosphorous slag( PS) is a new kind of cement. The total content of blended materials could increase if two additives were used. Using the same admixtures , the p...Blended cement containing blast furnace slag (BFS) and phosphorous slag( PS) is a new kind of cement. The total content of blended materials could increase if two additives were used. Using the same admixtures , the properties of the blended cement with 70% additives could reach the standard of 525-grade slag cement according to GB. The strength of cement with 80% additives could reach the standard of 425-grade slag cement. The tests of strength, pore structure, hydration products, inhibiting alkali-aggregate reaction, resistance to sulfate corrosion of BFS-PSC were performed.展开更多
Y1.94-xMgxO2S:0.06Ti (0≤x≤0.10) phosphors with long afterglow were synthesized by solid state reaction route. The photoluminescence spectra, decay curves, thermoluminescent spectra and chromaticity coordinate curves...Y1.94-xMgxO2S:0.06Ti (0≤x≤0.10) phosphors with long afterglow were synthesized by solid state reaction route. The photoluminescence spectra, decay curves, thermoluminescent spectra and chromaticity coordinate curves were investigated. The results show that the luminescence intensity of Y1.94-xMgxO2S :0.06Ti (0≤x≤0. 10) phosphors decrease gradually with increasing Mg2+ ion content, and the shape of luminescence spectra and chromaticity coordinate change as well. Furthermore, two thermoluminescent peaks in single Ti-doped Y2O2S sample are found at 91.8 and 221.5℃, respectively. Nevertheless, significant different spectra were found for the Mg, Ti co-doped Y2O2S samples that three thermoluminescence peaks appear at 52.3, 141.7 and 226.8℃, respectively. These results indicate that the co-doped Mg ion changes the inherent trap depth of single Ti-doped Y2O2S: Ti phosphor, and induces simultaneously a new trap level in the Y1.94-xMgxO2S:0.06Ti phosphor. Based on the analysis of thermoluminescent spectra, photolumi-nescent spectra, decay curve and crystal structure defect, it was proposed that the varied structure defect and introduced new trap level by the doped Mg2+ ions should be responsible for reducing luminescence intensity and varying color in the Y1.94-x Mgx O2S : 0.06Ti phosphor.展开更多
A red-emitting phosphor GdNbO4：Eu3＋,Bi3＋ was prepared by a high temperature solid-state reaction technique. The phosphor was characterized by X-ray diffraction （XRD）, particle size analyzer and fluorescence spect...A red-emitting phosphor GdNbO4：Eu3＋,Bi3＋ was prepared by a high temperature solid-state reaction technique. The phosphor was characterized by X-ray diffraction （XRD）, particle size analyzer and fluorescence spectrometer. The single phase of GdNbO4：Eu3＋,Bi3＋ was obtained at 1150~C and the average particle diameter was about 2.30 μm. Excitation and emission spectra reveal that the phosphor can be ef- ficiently excited by ultraviolet （UV） light （394 nm） and emit the strong red light of 612 nm due to the Eu3＋ transition of SD0~TF2. The opti- mum content of Eu3＋ doped in the phosphor GdNbOn：Eu3＋ is 20mo1%. The phosphor Gdo.80NbO4：0.20Eu3＋,0.03Bi3＋ shows much stronger photoluminescence intensity and better chromaticity coordinates （x=0.642, 0.352） than GdNbO4：Eu3＋. It is confirmed that Gdo.80NbO4：0.20Eu3＋,0.03Bi3＋ is a potential candidate for near-UV chip-based white light emitting diodes.展开更多
YAl3 （BO3）4： Eu^3＋ phosphors were prepared by the conventional solid state reaction. The phase structure and morphology were investigated by X-ray diffraction （XRD） and scanning electron microscope （SEM）. Dopi...YAl3 （BO3）4： Eu^3＋ phosphors were prepared by the conventional solid state reaction. The phase structure and morphology were investigated by X-ray diffraction （XRD） and scanning electron microscope （SEM）. Doping YAl3（BO3）4： Eu^3＋ phosphors with concentration of Eu^3＋ ions of 0, 2, 5, 8 and 10 mol% were studied and their luminescent properties at room temperature were discussed. The excitation spectrum of Y0.95Eu0.05Al3（BO3）4 was composed of a broad band centered at about 252 nm and a group of lines in the longer wavelength region. In the emission spectra, the peak wavelength was about 614 nm under a 252 nm UV excitation. The optimal doping concentration of Eu^3＋ ions in YAl3（BO3）4： Eu^3＋ phosphors was 8 mol%.展开更多
基金Suported by the breeding programs of Sichuan University(SCU2015C002)
文摘In a rotary kiln process for phosphoric acid production,the reaction between gaseous phosphorus pentoxide（P2O5）and phosphate ore and silica contained in feed balls（the so-called P2O5＂absorption＂）not only reduces phosphorous recovery but also generates a large amount of low melting-point side products.The products may give rise to formation of kiln ring,which interferes with kiln operation performance.In this study,the reactions of gaseous P2O5with solid calcium phosphate（Ca3（PO4）2）,silica（SiO2）and their mixture,respectively,were investigated via combined chemical analysis and various characterizations comprised of X-ray diffraction（XRD）,Fourier-transform infrared（FT-IR）spectroscopy,thermogravimetric analysis and differential scanning calorimeter（TG＆DSC）,and scanning electron microscopy and energy dispersive spectrometer（SEM＆EDS）.Attentions were focused on apparent morphology,phase transformation and thermal stability of the products of the P2O5＂absorption＂at different temperatures.The results show that the temperature significantly affected the＂absorption＂.The reaction between pure Ca3（PO4）2 and P2O5 occurred at 500℃.Calcium metaphosphate（Ca（PO3）2）was the primary product at the temperatures≤900℃ with its melting point≤900℃ while calcium pyrophosphate（Ca2P2O7）was obtained over 1000℃,which has a melting point≤1200℃.The＂absorption＂by pure SiO2 started at 800℃ and the most significant reaction occurred at 1000℃ with formation of silicon pyrophosphate（SiP2O7）product of melting point≤1000℃.Using mixed Ca3（PO4）2and SiO2as raw material,the＂absorption＂by Ca3（PO4）2 was enhanced due to existence of silica.At 600–700℃,silica was inert to P2O5and thus formed a porous structure in the raw material,which accelerated diffusion of gaseous P2O5inside the mixture.At higher temperatures,the combined＂absorption＂by calcium phosphate and reaction between silicon dioxide and the＂absorption＂product calcium pyrophosphate,reinforced the＂absorption＂by the mixture.Besides,it was found that both Ca（PO3）2and SiP2O7were unstable at high temperatures and would decompose to Ca2P2O7and SiO2,respectively,at over 1000℃ and 1100℃ with the release of gaseous P2O5at the same time.
基金Funded by the Primary Research and Development Plan of Jiangsu Province(No.BE2016175)。
文摘In this study,a single-doped phosphors yttrium aluminum garnet(Y_(3)Al_(5)O_(12),YAG):Ce^(3+),single-doped YAG:Sc^(3+),and double-doped phosphors YAG:Ce^(3+),Sc^(3+) were prepared by spark plasma sintering(SPS)(lower than 1 200℃).The characteristics of synthesized phosphors were determined using scanning electron microscopy(SEM),X-ray diffraction(XRD),and fluorescence spectroscopy.During SPS,the lattice structure of YAG was maintained by the added Ce^(3+) and Sc^(3+).The emission wavelength of YAG:Ce^(3+) prepared from SPS(425-700 nm) was wider compared to that of YAG:Ce^(3+) prepared from high-temperature solid-state reaction(HSSR)(500-700 nm).The incorporation of low-dose Sc^(3+) in YAG:Ce^(3+) moved the emission peak towards the short wavelength.
基金National Research Foundation of Korea(NRF),Grant/Award Number:2021R1A2C2012685Korea Institute of Energy Technology Evaluation and Planning(KETEP),Grant/Award Number:20203020030010Ministry of Trade,Industry&Energy(MOTIE,Korea),Grant/Award Number:20020400。
文摘One of the primary challenges in relation to phosphoric acid fuel cells is catalyst poisoning by phosphate anions that occurs at the interface between metal nanoparticles and the electrolyte.The strong adsorption of phosphate anions on the catalyst surface limits the active sites for the oxygen reduction reaction(ORR),significantly deteriorating fuel cell performance.Here,antipoisoning catalysts consisting of Pt-based nanoparticles encapsulated in an ultrathin carbon shell that can be used as a molecular sieve layer are rationally designed.The pore structure of the carbon shells is systematically regulated at the atomic level by high-temperature gas treatment,allowing O_(2) molecules to selectively react on the active sites of the metal nanoparticles through the molecular sieves.Besides,the carbon shell,as a protective layer,effectively prevents metal dissolution from the catalyst during a long-term operation.Consequently,the defect-controlled carbon shell leads to outstanding ORR activity and durability of the hybrid catalyst even in phosphoric acid electrolytes.
基金supported by the Climate Change Response Project (NRF-2019M1A2A2065612)the Brainlink Project (NRF2022H1D3A3A01081140)+3 种基金the NRF-2021R1A4A3027878 and the No. RS-2023-00212273 funded by the Ministry of Science and ICT of Korea via National Research Foundationresearch funds from Hanhwa Solutions Chemicals (1.220029.01)UNIST (1.190013.01)supported by the Institute for Basic Science (IBS-R019-D1)。
文摘Electrochemical N_(2) reduction reaction(eNRR) over Cu-based catalysts suffers from an intrinsically low activity of Cu for activation of stable N_(2) molecules and the limited supply of N_(2) to the catalyst due to its low solubility in aqueous electrolytes.Herein,we propose phosphorus-activated Cu electrocatalysts to generate electron-deficient Cu sites on the catalyst surface to promote the adsorption of N_(2) molecules.The eNRR system is further modified using a gas diffusion electrode(GDE) coated with polytetrafluoroethylene(PTFE) to form an effective three-phase boundary of liquid water-gas N_(2)-solid catalyst to facilitate easy access of N_(2) to the catalytic sites.As a result,the new catalyst in the flow-type cell records a Faradaic efficiency of 13.15% and an NH_(3) production rate of 7.69 μg h^(-1) cm^(-2) at-0.2 V_(RHE),which represent 3.56 and 59.2 times increases from those obtained with a pristine Cu electrode in a typical electrolytic cell.This work represents a successful demonstration of dual modification strategies;catalyst modification and N_(2) supplying system engineering,and the results would provide a useful platform for further developments of electrocatalysts and reaction systems.
基金supported by the National Natural Science Foundation of China(No.22162004)the Natural Science Foundation of Guangxi Province(No.2022JJD120011)the Opening Project of Guangxi Key Laboratory of Information Materials(No.211025-K).
文摘It is still a lack of bifunctional catalysts for ammonia oxidation reaction(AOR)and hydrogen evolution reaction(HER)due to their different reaction mechanisms.In this work,P is doped into PtZn alloy by calcination with NaH_(2)PO_(2) as P source to induce the lattice tensile strain of Pt and the electronic interaction between P and Zn,which optimizes the AOR and HER activity simultaneously.The sample with the optimal P content can drive the AOR peak current density of 293.6 mA·mgPt^(-1),which is almost 2.7 times of Pt.For HER,the overpotential at^(-1)0 mA·cm^(-2) is only 23 mV with Tafel slope of 34.1 mV·dec^(-1).Furthermore,only 0.59 V is needed to obtain 50 mA·mgPt^(-1) for ammonia electrolysis under a two-electrode system.Therefore,this work shows an ingenious method to design bifunctional catalysts for ammonia electrolysis.
文摘Blended cement containing blast furnace slag (BFS) and phosphorous slag( PS) is a new kind of cement. The total content of blended materials could increase if two additives were used. Using the same admixtures , the properties of the blended cement with 70% additives could reach the standard of 525-grade slag cement according to GB. The strength of cement with 80% additives could reach the standard of 425-grade slag cement. The tests of strength, pore structure, hydration products, inhibiting alkali-aggregate reaction, resistance to sulfate corrosion of BFS-PSC were performed.
基金Project supported by SRF for ROCS, SEM (2003-14), and Science and Technology Department of Zhejiang Province (2005C31019)
文摘Y1.94-xMgxO2S:0.06Ti (0≤x≤0.10) phosphors with long afterglow were synthesized by solid state reaction route. The photoluminescence spectra, decay curves, thermoluminescent spectra and chromaticity coordinate curves were investigated. The results show that the luminescence intensity of Y1.94-xMgxO2S :0.06Ti (0≤x≤0. 10) phosphors decrease gradually with increasing Mg2+ ion content, and the shape of luminescence spectra and chromaticity coordinate change as well. Furthermore, two thermoluminescent peaks in single Ti-doped Y2O2S sample are found at 91.8 and 221.5℃, respectively. Nevertheless, significant different spectra were found for the Mg, Ti co-doped Y2O2S samples that three thermoluminescence peaks appear at 52.3, 141.7 and 226.8℃, respectively. These results indicate that the co-doped Mg ion changes the inherent trap depth of single Ti-doped Y2O2S: Ti phosphor, and induces simultaneously a new trap level in the Y1.94-xMgxO2S:0.06Ti phosphor. Based on the analysis of thermoluminescent spectra, photolumi-nescent spectra, decay curve and crystal structure defect, it was proposed that the varied structure defect and introduced new trap level by the doped Mg2+ ions should be responsible for reducing luminescence intensity and varying color in the Y1.94-x Mgx O2S : 0.06Ti phosphor.
基金the National"12th Five-year"Science and Technology Support Program of China(No.2011BAE22B03-3)the Project of Chong qing Scientific and Technological Commission(No.CSTC2010AA4048)
文摘A red-emitting phosphor GdNbO4：Eu3＋,Bi3＋ was prepared by a high temperature solid-state reaction technique. The phosphor was characterized by X-ray diffraction （XRD）, particle size analyzer and fluorescence spectrometer. The single phase of GdNbO4：Eu3＋,Bi3＋ was obtained at 1150~C and the average particle diameter was about 2.30 μm. Excitation and emission spectra reveal that the phosphor can be ef- ficiently excited by ultraviolet （UV） light （394 nm） and emit the strong red light of 612 nm due to the Eu3＋ transition of SD0~TF2. The opti- mum content of Eu3＋ doped in the phosphor GdNbOn：Eu3＋ is 20mo1%. The phosphor Gdo.80NbO4：0.20Eu3＋,0.03Bi3＋ shows much stronger photoluminescence intensity and better chromaticity coordinates （x=0.642, 0.352） than GdNbO4：Eu3＋. It is confirmed that Gdo.80NbO4：0.20Eu3＋,0.03Bi3＋ is a potential candidate for near-UV chip-based white light emitting diodes.
文摘YAl3 （BO3）4： Eu^3＋ phosphors were prepared by the conventional solid state reaction. The phase structure and morphology were investigated by X-ray diffraction （XRD） and scanning electron microscope （SEM）. Doping YAl3（BO3）4： Eu^3＋ phosphors with concentration of Eu^3＋ ions of 0, 2, 5, 8 and 10 mol% were studied and their luminescent properties at room temperature were discussed. The excitation spectrum of Y0.95Eu0.05Al3（BO3）4 was composed of a broad band centered at about 252 nm and a group of lines in the longer wavelength region. In the emission spectra, the peak wavelength was about 614 nm under a 252 nm UV excitation. The optimal doping concentration of Eu^3＋ ions in YAl3（BO3）4： Eu^3＋ phosphors was 8 mol%.
