In this study,hierarchical Ag/La2 O2 CO3 micro/nanostructures(MNSs)were synthesized by in situ loading Ag nanoparticles(NPs)on the surface of the La2 O2 CO3 MNSs.The prepared La2 O2 CO3 MNSs present flower-like shape ...In this study,hierarchical Ag/La2 O2 CO3 micro/nanostructures(MNSs)were synthesized by in situ loading Ag nanoparticles(NPs)on the surface of the La2 O2 CO3 MNSs.The prepared La2 O2 CO3 MNSs present flower-like shape and can be tuned by the molar ratio of La(NO3)3 and CO(NH2)2.In the molar ratio of 1:2 to 1:55,the La2 O2 CO3 MNSs mainly consist of polyhedral rods,irregular rods and irregular spindles and their size is about 10,8 and 7μm,respectively.After loading Ag NPs,the spindle-like Ag/La2 O2 CO3 MNSs were used for phosphate removal and antibacterial activity.At the initial phosphate concentration of20 mg/L,the removal rate is 59.6%.The Ag/La2 O2 CO3 MNSs have significant antibacterial activity and their MIC values for S.aureus and E.coli are 31.3 and 15.6μg/mL,respectively.The results indicate that Ag/La2 O2 CO3 MNSs may have good application prospects in open water to inhibit bacterial growth.展开更多
Devising S-scheme heterostructure is considered as a cutting-edge strategy for advanced photocatalysts with effectively segregated photo-carriers and prominent redox potential for emerging organic pollutants control.H...Devising S-scheme heterostructure is considered as a cutting-edge strategy for advanced photocatalysts with effectively segregated photo-carriers and prominent redox potential for emerging organic pollutants control.Herein,an S-scheme Ag_(2)CO_(3)/C_(3)N_(5) heterojunction photocatalyst was developed via a simple in situ chemical deposition procedure,and further photoreduction operation made metallic Ag(size:3.5–12.5 nm)being in situ formed on Ag_(2)CO_(3)/C_(3)N_(5) for a plasmonic S-scheme Ag/Ag_(2)CO_(3)/C_(3)N_(5) heterojunction photocatalyst.Consequently,Ag/Ag_(2)CO_(3)/C_(3)N_(5) manifests pronouncedly upgraded photocatalytic performance toward oxytetracycline degradation with a superior photoreaction rate constant of 0.0475 min‒1,which is 13.2,3.9 and 2.2 folds that of C_(3)N_(5),Ag_(2)CO_(3),and Ag_(2)CO_(3)/C_(3)N_(5),respectively.As evidenced by comprehensive characterizations and density functional theory calculations,the localized surface plasmon resonance effect of metallic Ag and the unique S-scheme charge transfer mechanism in 0D/0D/2D Ag/Ag_(2)CO_(3)/C_(3)N_(5) collaboratively strengthen the visible-light absorption,and facilitate the effective separation of powerful charge carriers,thereby significantly promoting the generation of reactive species like·OH^(-),h^(+)and·O_(2)^(-)for efficient oxytetracycline destruction.Moreover,four consecutive cycles demonstrate the reusability of Ag/Ag_(2)CO_(3)/C_(3)N_(5).Furthermore,the authentic water purification tests affirm its practical application potential.This work not only provides a candidate strategy for advancing S-scheme heterojunction photocatalysts but also makes a certain contribution to water decontamination.展开更多
Ag/Al_(2)O_(3) powders are highly effective catalytic materials utilized in the epoxidation of ethylene to produce ethylene oxide.One of the critical challenges in this catalytic process is the stability of nano-sized...Ag/Al_(2)O_(3) powders are highly effective catalytic materials utilized in the epoxidation of ethylene to produce ethylene oxide.One of the critical challenges in this catalytic process is the stability of nano-sized Ag particles,especially during high-temperature catalysis.However,this issue can be effectively addressed through in-situ reaction synthesis.To gain a deeper understanding of the underlying mechanisms,the phase transformation process and the thermodynamic mechanism of the oxidation reaction in the Ag/Al_(2)O_(3) system have been investigated using firstprinciples thermodynamic calculations in conjunction with traditional thermodynamic data.These calculations,whose accuracy has been verified,provide valuable insights into the behavior of Ag and Al under different conditions.The results indicate that,during AgAl solid-solution oxidation,Ag-containing Al preferentially forms the stable intermediate phase Ag2Al instead of undergoing direct oxidation;this pathway becomes thermodynamically more favorable at higher Ag concentrations.With increasing temperature,Ag2Al is further oxidized to yield Ag and Al_(2)O_(3).It is also found that above 237℃,Ag2O and AgAlO2 become unstable.The overall reaction pathway is solid solution→Ag2Al→Ag+Al_(2)O_(3).This comprehensive study provides a robust theoretical calculation basis for the development and optimization of in-situ reaction-synthesized Ag/Al_(2)O_(3) powder composite materials,which have significant potential for practical applications in catalysis.展开更多
Piezoelectric effect,plasma effect and semiconductor heterostructure are important strategies for enhanced photocatalytic performance.Herein,we developed a novel heterostructure piezoelectric photocatalyst,Ag/Ag_(2)S/...Piezoelectric effect,plasma effect and semiconductor heterostructure are important strategies for enhanced photocatalytic performance.Herein,we developed a novel heterostructure piezoelectric photocatalyst,Ag/Ag_(2)S/BiFeO_(3)(AAS/BFO),for photocatalytic degradation of ciprofloxacin from water.Experimental results verified the enhancement of combining heterostructure piezoelectric polarization effect,which promotes efficient migration and separation of photogenerated carriers due to the localized surface plasmon resonance effect of Ag nanoparticles.Additionally,the introduction of Ag_(2)S constructs a new heterostructure,that enhances the electron transport rate and improves the separation efficiency on electron-hole pairs.Under ultrasonic stimulation and visible light irradiation,the degradation efficiencies of 15%-AAS/BFO towards ciprofloxacin,methyl orange and methylene blue are significantly enhanced compared to pure BFO fibers.The demonstrated AAS/BFO material based on the synergistic piezoelectric effect and plasmon heterostructure shows potential in efficient organic pollutants water treatment and transforming mechanical energy into chemical energy.展开更多
The single phase La2（CO3）3·3.4H2 O was synthesized by hydrothermal method. The thermal decomposition and intermediates and final solid products of La2（CO3）3·3.4H2O from 30 to 1000 °C were characteri...The single phase La2（CO3）3·3.4H2 O was synthesized by hydrothermal method. The thermal decomposition and intermediates and final solid products of La2（CO3）3·3.4H2O from 30 to 1000 °C were characterized by XRD, FTIR and DTA-TG. The kinetics of dehydration of La2（CO3）3·3.4H2O in the temperature range of 30-366 °C was investigated under non-isothermal conditions. Flynn-Wall-Ozawa and Friedman isoconversion methods were used to calculate the activation energy and analyze the reaction steps; multivariate non-linear regression program was applied to determine the most probable mechanism and the kinetic parameters. The results show that the thermal dehydration of La2（CO3）3·3.4H2O is a kind of three-step competitive reaction, and controlled by an n-order initial reaction followed by n-order competitive reaction（FnFnFn model）. The activation energy matching with the most probable model is close to value obtained by Friedman method. The fitting curves match the original TG-DTG curves very well.展开更多
基金Project supported by the National Natural Science Foundation of China(21271062)。
文摘In this study,hierarchical Ag/La2 O2 CO3 micro/nanostructures(MNSs)were synthesized by in situ loading Ag nanoparticles(NPs)on the surface of the La2 O2 CO3 MNSs.The prepared La2 O2 CO3 MNSs present flower-like shape and can be tuned by the molar ratio of La(NO3)3 and CO(NH2)2.In the molar ratio of 1:2 to 1:55,the La2 O2 CO3 MNSs mainly consist of polyhedral rods,irregular rods and irregular spindles and their size is about 10,8 and 7μm,respectively.After loading Ag NPs,the spindle-like Ag/La2 O2 CO3 MNSs were used for phosphate removal and antibacterial activity.At the initial phosphate concentration of20 mg/L,the removal rate is 59.6%.The Ag/La2 O2 CO3 MNSs have significant antibacterial activity and their MIC values for S.aureus and E.coli are 31.3 and 15.6μg/mL,respectively.The results indicate that Ag/La2 O2 CO3 MNSs may have good application prospects in open water to inhibit bacterial growth.
文摘Devising S-scheme heterostructure is considered as a cutting-edge strategy for advanced photocatalysts with effectively segregated photo-carriers and prominent redox potential for emerging organic pollutants control.Herein,an S-scheme Ag_(2)CO_(3)/C_(3)N_(5) heterojunction photocatalyst was developed via a simple in situ chemical deposition procedure,and further photoreduction operation made metallic Ag(size:3.5–12.5 nm)being in situ formed on Ag_(2)CO_(3)/C_(3)N_(5) for a plasmonic S-scheme Ag/Ag_(2)CO_(3)/C_(3)N_(5) heterojunction photocatalyst.Consequently,Ag/Ag_(2)CO_(3)/C_(3)N_(5) manifests pronouncedly upgraded photocatalytic performance toward oxytetracycline degradation with a superior photoreaction rate constant of 0.0475 min‒1,which is 13.2,3.9 and 2.2 folds that of C_(3)N_(5),Ag_(2)CO_(3),and Ag_(2)CO_(3)/C_(3)N_(5),respectively.As evidenced by comprehensive characterizations and density functional theory calculations,the localized surface plasmon resonance effect of metallic Ag and the unique S-scheme charge transfer mechanism in 0D/0D/2D Ag/Ag_(2)CO_(3)/C_(3)N_(5) collaboratively strengthen the visible-light absorption,and facilitate the effective separation of powerful charge carriers,thereby significantly promoting the generation of reactive species like·OH^(-),h^(+)and·O_(2)^(-)for efficient oxytetracycline destruction.Moreover,four consecutive cycles demonstrate the reusability of Ag/Ag_(2)CO_(3)/C_(3)N_(5).Furthermore,the authentic water purification tests affirm its practical application potential.This work not only provides a candidate strategy for advancing S-scheme heterojunction photocatalysts but also makes a certain contribution to water decontamination.
基金sponsored by Major Science and Technology Project of the Yunnan Provincial Department of Science and Technology(202502AB080011)Yunnan Province Industrial High-Tech Project(202403AA080015)Special Science and Technology Research Project of Yunnan Province for the South Asia and Southeast Asia Innovation Center(202403AP140006).
文摘Ag/Al_(2)O_(3) powders are highly effective catalytic materials utilized in the epoxidation of ethylene to produce ethylene oxide.One of the critical challenges in this catalytic process is the stability of nano-sized Ag particles,especially during high-temperature catalysis.However,this issue can be effectively addressed through in-situ reaction synthesis.To gain a deeper understanding of the underlying mechanisms,the phase transformation process and the thermodynamic mechanism of the oxidation reaction in the Ag/Al_(2)O_(3) system have been investigated using firstprinciples thermodynamic calculations in conjunction with traditional thermodynamic data.These calculations,whose accuracy has been verified,provide valuable insights into the behavior of Ag and Al under different conditions.The results indicate that,during AgAl solid-solution oxidation,Ag-containing Al preferentially forms the stable intermediate phase Ag2Al instead of undergoing direct oxidation;this pathway becomes thermodynamically more favorable at higher Ag concentrations.With increasing temperature,Ag2Al is further oxidized to yield Ag and Al_(2)O_(3).It is also found that above 237℃,Ag2O and AgAlO2 become unstable.The overall reaction pathway is solid solution→Ag2Al→Ag+Al_(2)O_(3).This comprehensive study provides a robust theoretical calculation basis for the development and optimization of in-situ reaction-synthesized Ag/Al_(2)O_(3) powder composite materials,which have significant potential for practical applications in catalysis.
基金supported by the National Natural Science Foundation of China(Nos.52372090 and 52073177)the National Natural Science Foundation of Guangdong,China(No.2023A1515010947)Shenzhen Basic Research Program(No.JCYJ20220531102207017).
文摘Piezoelectric effect,plasma effect and semiconductor heterostructure are important strategies for enhanced photocatalytic performance.Herein,we developed a novel heterostructure piezoelectric photocatalyst,Ag/Ag_(2)S/BiFeO_(3)(AAS/BFO),for photocatalytic degradation of ciprofloxacin from water.Experimental results verified the enhancement of combining heterostructure piezoelectric polarization effect,which promotes efficient migration and separation of photogenerated carriers due to the localized surface plasmon resonance effect of Ag nanoparticles.Additionally,the introduction of Ag_(2)S constructs a new heterostructure,that enhances the electron transport rate and improves the separation efficiency on electron-hole pairs.Under ultrasonic stimulation and visible light irradiation,the degradation efficiencies of 15%-AAS/BFO towards ciprofloxacin,methyl orange and methylene blue are significantly enhanced compared to pure BFO fibers.The demonstrated AAS/BFO material based on the synergistic piezoelectric effect and plasmon heterostructure shows potential in efficient organic pollutants water treatment and transforming mechanical energy into chemical energy.
基金Project(201011005-5)supported by the National Land and Resources Public Welfare Scientific Research Project of ChinaProject(41030426)supported by the National Natural Science Foundation of China+1 种基金Project(20095122110015)supported by Specialized Research Fund for the Doctoral Program of Higher Education of ChinaProject(2010-32)supported by Scientific Research Foundation of the Education Ministry for Returned Chinese Scholars,China
文摘The single phase La2（CO3）3·3.4H2 O was synthesized by hydrothermal method. The thermal decomposition and intermediates and final solid products of La2（CO3）3·3.4H2O from 30 to 1000 °C were characterized by XRD, FTIR and DTA-TG. The kinetics of dehydration of La2（CO3）3·3.4H2O in the temperature range of 30-366 °C was investigated under non-isothermal conditions. Flynn-Wall-Ozawa and Friedman isoconversion methods were used to calculate the activation energy and analyze the reaction steps; multivariate non-linear regression program was applied to determine the most probable mechanism and the kinetic parameters. The results show that the thermal dehydration of La2（CO3）3·3.4H2O is a kind of three-step competitive reaction, and controlled by an n-order initial reaction followed by n-order competitive reaction（FnFnFn model）. The activation energy matching with the most probable model is close to value obtained by Friedman method. The fitting curves match the original TG-DTG curves very well.
基金National Natural Science Foundation of China(51572076,51508172,51378183)Science and Technology Bureau of Xiangyang,and the Foundation of Hubei Key Laboratory of Low Dimensional Optoelectronic Materials and Devices(14XKL1002)
