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
Since the first discovery of gold deposits on the northeastern margin of the Jiaolai Basin in Shandong Province at the end of the 20^(th) century,seven medium-sized to large/super-large gold deposits have been identif...Since the first discovery of gold deposits on the northeastern margin of the Jiaolai Basin in Shandong Province at the end of the 20^(th) century,seven medium-sized to large/super-large gold deposits have been identified in this region,with cumulative proven gold resources of 223 t.This study reviewed the metallogenic and geochemical characteristics of various gold deposits in this region,examined the sources of their ore-forming fluids and materials,as well as their gold metallogenic epochs and processes,and developed a gold metallogenic model.The gold deposits in this region are governed by both dense fractures and detachment structural systems along basin margins,primarily categorized into the altered rock type and the pyrite-bearing carbonate vein type.The latter type,a recently discovered mineralization type in the Jiaodong Peninsula,enjoys high gold grade,a large scale,and high gold mineral fineness,suggesting considerable prospecting potential.Both types of gold deposits show metallogenic epochs ranging from 116 Ma to 119 Ma.Their ore-forming fluids are identified as a CO_(2)-NaCl-H_(2)O fluid system characterized by moderate to low temperatures,moderate to low salinity,and low density,with the pyrite-bearing carbonate vein-type gold deposits manifesting slightly higher salinity.The C-H-O,S,and Pb isotopes of hydrothermal minerals reveal that the ore-forming fluids and materials are characteristic of crust-mantle mixing.Specifically,they were derived from mantle fluids in the early stages,mixed with stratum water and meteoric water in the later stages for mineralization.The gold metallogenic process is identified as follows:During the Early Cretaceous,the subduction of the Pacific Plate and the destruction of the North China Craton led to asthenospheric upwelling.The resulting fluids,after metasomatizing the enriched mantle,differentiated and evolved into C-H-O ore-bearing fluids,which were then mixed with crustal fluids.The mixed fluids migrated to the shallow crust,where they mingled with stratum water and meteoric water.Then,the fluids underwent unloading and final mineralization in detachment fault tectonic systems on basin margins.Due to differences in mixed crustal materials or the surrounding rocks involved in water-rock interactions,altered rock-and pyrite-bearing carbonate vein-type gold deposits were formed in acidic and alkaline fluid environments,respectively.展开更多
Layered transition metal hydroxides show distinct advantages in separately co-catalyzing CO_(2)reduction and H_(2)O oxidation at the electron-accumulating and hole-accumulating sites of wrapped heterojunction photocat...Layered transition metal hydroxides show distinct advantages in separately co-catalyzing CO_(2)reduction and H_(2)O oxidation at the electron-accumulating and hole-accumulating sites of wrapped heterojunction photocatalysts,while concurrently preventing side reactions and photocorrosion on the semiconductor surface.Herein,Ni-Co bimetallic hydroxides with varying Ni/Co molar ratios(Ni_(x)Co_(1-x)(OH)_(2),x=1,0.75,0.5,0.25,and 0)were grown in situ on a model 2D/2D S-scheme heterojunction composed of Cu_(2)O nanosheets and Fe_(2)O_(3)nanoplates to form a series of Cu_(2)O/Fe_(2)O_(3)@Ni_(x)Co_(1-x)(OH)_(2)(CF@NiCo)photocatalysts.The combined experimental and theoretical investigation demonstrates that incorporating an appropriate amount of Co into Ni(OH)_(2)not only modulates the energy band structure of Ni_(x)Co_(1-x)(OH)_(2),balances the electron-and hole-trapping abilities of the bifunctional cocatalyst and maximizes the charge separation efficiency of the heterojunction,but also regulates the d-band center of Ni_(x)Co_(1-x)(OH)_(2),reinforcing the adsorption and activation of CO_(2)and H_(2)O on the cocatalyst surface and lowering the rate-limiting barriers in the CO_(2)-to-CO and H_(2)O-to-O_(2)conversion.Benefiting from the Ni-Co synergy,the redox reactions proceed stoichiometrically.The optimized CF@Ni_(0.75)Co_(0.25)achieves CO and O_(2)yields of 552.7 and 313.0μmol gcat^(-1)h^(-1),respectively,11.3/9.9,1.6/1.7,and 4.5/5.9-fold higher than those of CF,CF@Ni,and CF@Co.This study offers valuable insights into the design of bifunctional noble-metal-free cocatalysts for high-performance artificial photosynthesis.展开更多
In this paper, the Gd2O3：Eu3＋,Tb3＋phosphors with different doping concentrations of Eu3＋and Tb3＋ions were prepared by a hydrothermal method for nanocrystals and the solid-phase method for microcrystals. The inter...In this paper, the Gd2O3：Eu3＋,Tb3＋phosphors with different doping concentrations of Eu3＋and Tb3＋ions were prepared by a hydrothermal method for nanocrystals and the solid-phase method for microcrystals. The interaction of the doped ions with different concentrations and the luminescent properties of the nanocrystals and microcrystals were studied systematically. Their structure and morphology of Gd2O3：Eu3＋,Tb3＋phosphors were analyzed by means of X-ray powder diffraction （XRD）, transmission electron mi-croscopy （TEM） and scanning electron microscopy （SEM）. The photoluminescence （PL） properties of Gd2O3：Eu3＋,Tb3＋phosphors were also systematically investigated. The results indicated that when the concentration of doped Eu3＋was fixed at 1 mol.%, the emis-sion intensity of Eu3＋ions was degenerating with Tb3＋content increasing, while when the Tb3＋content was fixed at 1 mol.%, the emission intensity of Tb3＋ions reached a maximum when the concentration of Eu3＋was 2 mol.%, implying that the energy transfer from Eu3＋to Tb3＋took place. In addition, Tb3＋could inspire blue-green light and the Eu3＋could inspire red light. Therefore co-doping systems by controlling the doping concentration and the hosts are the potential white emission materials.展开更多
A series of Tb^3+ mono-doped and Ce^3+-Tb^3+ co-doped Sr3Gd2(Si3O9)2 phosphors with high thermal stability and quantum yields were successfully prepared via the solid state reaction. The as-prepared Sr3Gd2(Si3O9)2:Tb^...A series of Tb^3+ mono-doped and Ce^3+-Tb^3+ co-doped Sr3Gd2(Si3O9)2 phosphors with high thermal stability and quantum yields were successfully prepared via the solid state reaction. The as-prepared Sr3Gd2(Si3O9)2:Tb^3+ samples showed broad excitation spectrum from 250 to 400 nm and presented characteristic emission transitions ^5D4→^7FJ(J=6, 5, 4, 3) of Tb^3+ under 313 nm excitation, which were located at about 488, 541, 584 and 620 nm. The emission intensities of Tb^3+ rose steadily in Sr3Gd2(Si3O9)2 host with the increase of Tb^3+ concentration even though Gd^3+ ions were completely replaced by Tb^3+ ions. The Ce^3+ ion as a sensitizer could efficiently improve the performance of Tb^3+ ion. First, with Ce^3+ co-doping, the excitation spectrum of Tb^3+ monitored at 541 nm showed a similar band that responds to the violet emission of Ce^3+ monitored at 416 nm. Second, the quantum yields of Sr3Gd2(Si3O9)2:Tb^3+ phosphors could be enhanced from 26.6% to 80.2% by co-doping Ce^3+. Finally, the co-doping of Ce^3+ was also effective to improve the thermal stability of Sr3Gd2(Si3O9)2:Tb^3+. As the temperature rose to 150 oC, the emission intensity of Tb^3+ remained at about 83.6% of that measured at room temperature, which was better than the commercial YAG:Ce phosphor in terms of their thermal quenching properties. These results indicated that the as-prepared Sr3Gd2(Si3O9)2:Tb^3+,Ce^3+ samples could be used as green emission phosphors for possible applications in near ultraviolet based WLEDs.展开更多
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.
基金supported by the Program of the National Natural Science Foundation of China(Nos.41973048,U2006201)the Open Project of State Key Laboratory of Geological Processes and Mineral Resources(No.GPMR202203)+1 种基金the Key R&D Program of Shandong Province(No.2023CXGC011001),the Taishan Scholars.Program(tstp20240847)the Open Project of Shandong Engineering Research Center of Application and Development of Big Data for Deep Gold Exploration(No.SDK202207)。
文摘Since the first discovery of gold deposits on the northeastern margin of the Jiaolai Basin in Shandong Province at the end of the 20^(th) century,seven medium-sized to large/super-large gold deposits have been identified in this region,with cumulative proven gold resources of 223 t.This study reviewed the metallogenic and geochemical characteristics of various gold deposits in this region,examined the sources of their ore-forming fluids and materials,as well as their gold metallogenic epochs and processes,and developed a gold metallogenic model.The gold deposits in this region are governed by both dense fractures and detachment structural systems along basin margins,primarily categorized into the altered rock type and the pyrite-bearing carbonate vein type.The latter type,a recently discovered mineralization type in the Jiaodong Peninsula,enjoys high gold grade,a large scale,and high gold mineral fineness,suggesting considerable prospecting potential.Both types of gold deposits show metallogenic epochs ranging from 116 Ma to 119 Ma.Their ore-forming fluids are identified as a CO_(2)-NaCl-H_(2)O fluid system characterized by moderate to low temperatures,moderate to low salinity,and low density,with the pyrite-bearing carbonate vein-type gold deposits manifesting slightly higher salinity.The C-H-O,S,and Pb isotopes of hydrothermal minerals reveal that the ore-forming fluids and materials are characteristic of crust-mantle mixing.Specifically,they were derived from mantle fluids in the early stages,mixed with stratum water and meteoric water in the later stages for mineralization.The gold metallogenic process is identified as follows:During the Early Cretaceous,the subduction of the Pacific Plate and the destruction of the North China Craton led to asthenospheric upwelling.The resulting fluids,after metasomatizing the enriched mantle,differentiated and evolved into C-H-O ore-bearing fluids,which were then mixed with crustal fluids.The mixed fluids migrated to the shallow crust,where they mingled with stratum water and meteoric water.Then,the fluids underwent unloading and final mineralization in detachment fault tectonic systems on basin margins.Due to differences in mixed crustal materials or the surrounding rocks involved in water-rock interactions,altered rock-and pyrite-bearing carbonate vein-type gold deposits were formed in acidic and alkaline fluid environments,respectively.
文摘Layered transition metal hydroxides show distinct advantages in separately co-catalyzing CO_(2)reduction and H_(2)O oxidation at the electron-accumulating and hole-accumulating sites of wrapped heterojunction photocatalysts,while concurrently preventing side reactions and photocorrosion on the semiconductor surface.Herein,Ni-Co bimetallic hydroxides with varying Ni/Co molar ratios(Ni_(x)Co_(1-x)(OH)_(2),x=1,0.75,0.5,0.25,and 0)were grown in situ on a model 2D/2D S-scheme heterojunction composed of Cu_(2)O nanosheets and Fe_(2)O_(3)nanoplates to form a series of Cu_(2)O/Fe_(2)O_(3)@Ni_(x)Co_(1-x)(OH)_(2)(CF@NiCo)photocatalysts.The combined experimental and theoretical investigation demonstrates that incorporating an appropriate amount of Co into Ni(OH)_(2)not only modulates the energy band structure of Ni_(x)Co_(1-x)(OH)_(2),balances the electron-and hole-trapping abilities of the bifunctional cocatalyst and maximizes the charge separation efficiency of the heterojunction,but also regulates the d-band center of Ni_(x)Co_(1-x)(OH)_(2),reinforcing the adsorption and activation of CO_(2)and H_(2)O on the cocatalyst surface and lowering the rate-limiting barriers in the CO_(2)-to-CO and H_(2)O-to-O_(2)conversion.Benefiting from the Ni-Co synergy,the redox reactions proceed stoichiometrically.The optimized CF@Ni_(0.75)Co_(0.25)achieves CO and O_(2)yields of 552.7 and 313.0μmol gcat^(-1)h^(-1),respectively,11.3/9.9,1.6/1.7,and 4.5/5.9-fold higher than those of CF,CF@Ni,and CF@Co.This study offers valuable insights into the design of bifunctional noble-metal-free cocatalysts for high-performance artificial photosynthesis.
基金National Natural Science Foundation of China(12175254,U1832119)National Key R&D Program of China(2021YFE0104800)+2 种基金International Partnership Program of Chinese Academy of Sciences(121631KYSB20200039)International Cooperation Project of Shanghai Science and Technology Commission(20520750200)National Centre for Research and Development(WPC2/1/SCAPOL/2021)。
基金supported by Natural Science Foundation of Jiangxi Province(20132BAB206008)
文摘In this paper, the Gd2O3：Eu3＋,Tb3＋phosphors with different doping concentrations of Eu3＋and Tb3＋ions were prepared by a hydrothermal method for nanocrystals and the solid-phase method for microcrystals. The interaction of the doped ions with different concentrations and the luminescent properties of the nanocrystals and microcrystals were studied systematically. Their structure and morphology of Gd2O3：Eu3＋,Tb3＋phosphors were analyzed by means of X-ray powder diffraction （XRD）, transmission electron mi-croscopy （TEM） and scanning electron microscopy （SEM）. The photoluminescence （PL） properties of Gd2O3：Eu3＋,Tb3＋phosphors were also systematically investigated. The results indicated that when the concentration of doped Eu3＋was fixed at 1 mol.%, the emis-sion intensity of Eu3＋ions was degenerating with Tb3＋content increasing, while when the Tb3＋content was fixed at 1 mol.%, the emission intensity of Tb3＋ions reached a maximum when the concentration of Eu3＋was 2 mol.%, implying that the energy transfer from Eu3＋to Tb3＋took place. In addition, Tb3＋could inspire blue-green light and the Eu3＋could inspire red light. Therefore co-doping systems by controlling the doping concentration and the hosts are the potential white emission materials.
基金Project supported by National Natural Science Foundation of China(21571162)the Guangdong Province Enterprise-University-Academy Collaborative Project(2012B091100474)
文摘A series of Tb^3+ mono-doped and Ce^3+-Tb^3+ co-doped Sr3Gd2(Si3O9)2 phosphors with high thermal stability and quantum yields were successfully prepared via the solid state reaction. The as-prepared Sr3Gd2(Si3O9)2:Tb^3+ samples showed broad excitation spectrum from 250 to 400 nm and presented characteristic emission transitions ^5D4→^7FJ(J=6, 5, 4, 3) of Tb^3+ under 313 nm excitation, which were located at about 488, 541, 584 and 620 nm. The emission intensities of Tb^3+ rose steadily in Sr3Gd2(Si3O9)2 host with the increase of Tb^3+ concentration even though Gd^3+ ions were completely replaced by Tb^3+ ions. The Ce^3+ ion as a sensitizer could efficiently improve the performance of Tb^3+ ion. First, with Ce^3+ co-doping, the excitation spectrum of Tb^3+ monitored at 541 nm showed a similar band that responds to the violet emission of Ce^3+ monitored at 416 nm. Second, the quantum yields of Sr3Gd2(Si3O9)2:Tb^3+ phosphors could be enhanced from 26.6% to 80.2% by co-doping Ce^3+. Finally, the co-doping of Ce^3+ was also effective to improve the thermal stability of Sr3Gd2(Si3O9)2:Tb^3+. As the temperature rose to 150 oC, the emission intensity of Tb^3+ remained at about 83.6% of that measured at room temperature, which was better than the commercial YAG:Ce phosphor in terms of their thermal quenching properties. These results indicated that the as-prepared Sr3Gd2(Si3O9)2:Tb^3+,Ce^3+ samples could be used as green emission phosphors for possible applications in near ultraviolet based WLEDs.
