Ternary metal halides based on Cu(I)and Ag(I)have attracted intensive attention in optoelectronic applications due to their excellent luminescent properties,low toxicity,and robust stability.While the self-trapped exc...Ternary metal halides based on Cu(I)and Ag(I)have attracted intensive attention in optoelectronic applications due to their excellent luminescent properties,low toxicity,and robust stability.While the self-trapped excitons(STEs)emission mechanisms of Cu(I)halides are well understood,the STEs in Ag(I)halides remain less thoroughly explored.This study explores the STE emission efficiency within the A_(2)AgX_(3)(A=Rb,Cs;X=Cl,Br,I)system by identifying three distinct STE states in each material and calculating their configuration coordinate diagrams.We find that the STE emission efficiency in this system is mainly determined by STE stability and influenced by self-trapping and quenching barriers.Moreover,we investigate the impact of structural compactness on emission efficiency and find that the excessive electron–phonon coupling in this system can be reduced by increasing the structural compactness.The atomic packing factor is identified as a low-cost and effective descriptor for predicting STE emission efficiency in both Cs_(2)AgX_(3) and Rb_(2)AgX_(3) systems.These findings can deepen our understanding of STE behavior in metal halide materials and offer valuable insights for the design of efficient STE luminescent materials.The datasets presented in this paper are openly available in Science Data Bank at https://doi.org/10.57760/sciencedb.12094.展开更多
The mechanism of interaction relation between the rare-earth element Ce and elements Pb and Bi in Ag-based filler metal has been studied. The results show that the compounds CePb and CeBi with high melting point can b...The mechanism of interaction relation between the rare-earth element Ce and elements Pb and Bi in Ag-based filler metal has been studied. The results show that the compounds CePb and CeBi with high melting point can be easily produced between these three elements in the filler metal, which greatly limited the formation of the isolated phase Pb or Bi and also eliminated the bad effect of impurity elements Pb and Bi on the spreading property of Ag-based filler metal. The metallurgical and quantum-mechanical bond formation analysis show that a strong chemical affinity was existed between the rare-earth element Ce and impurity elements Pb and Bi, which was proved by the XRD analysis results.展开更多
Ag-based nano particles(NPs)catalysts have recently attracted in creasi ng atte ntion in NaBH4-assisted n itrophe nol reducti on,especially in 4?n itrophe nol(4?NP)reducti on.Moreover,Ag-based NPs catalysts are con si...Ag-based nano particles(NPs)catalysts have recently attracted in creasi ng atte ntion in NaBH4-assisted n itrophe nol reducti on,especially in 4?n itrophe nol(4?NP)reducti on.Moreover,Ag-based NPs catalysts are con sidered to be very promising for practical applicati ons because of their fascinating advantages,e.g.,easy preparation,relatively low cost and less toxicity,high activity and good stability.Basically,the size and shape of Ag NPs are well known as the key factors for achieving highly efficient catalytic reduction of 4-NP.In this review,three highly efficient Ag-based NPs catalysts(supported Ag NPs,anisotropic Ag NPs and bimetallic Ag NPs)are highlighted for the 4-NP reduction,in eluding the catalytic mecha nism and reactio n rate caused by their adjustments in size and shape.Although high catalytic activity has bee n demonstrated by several Ag-based NPs catalysts,further improvement in the catalytic performance is still desired.In terms of the most recent progress in Ag-based NPs catalysts for 4?NP reduction,this review provides a comprehensive assessment on the material selection,synthesis and catalytic characterizations of these catalysts.Moreover,this review aims to correlate the catalytic performance of Ag-based NPs catalysts with their size and shape,guiding the development of novel cost-effective and high-performance catalysts.展开更多
The atomic structures of liquid Ag-based binary alloys have been investigated in the solidification process by means of X-ray diffraction. The results of liquid structure show that there is a break point in the mean n...The atomic structures of liquid Ag-based binary alloys have been investigated in the solidification process by means of X-ray diffraction. The results of liquid structure show that there is a break point in the mean nearest neighbor distance r1 and the coordination number Nmin for glass-forming liquid, while the correlation radius rc and the coordination number Nmin display a monotone variational trend above the break point. It means glass-forming liquids have a steady changing in structure above liquidus and more inhomogeneous state at liquidus. We conclude that there is a strong correlation between liquid structure and glass forming ability in Ag-based binary alloys.展开更多
This article studies the effects of different Sn contents on the melting characteristics,microstructure,and mechanical properties of brazed joints of low-silver BAg5CuZn-0.3 wt.%La brazing material.A differential ther...This article studies the effects of different Sn contents on the melting characteristics,microstructure,and mechanical properties of brazed joints of low-silver BAg5CuZn-0.3 wt.%La brazing material.A differential thermal analyzer(HCR-1)was used to measure the solid-liquidus temperature of BAg5CuZn-0.3 wt.%La-xSn brazing material.The results show that the addition of Sn element effect-ively reduces the solid-liquidus temperature of BAg5CuZn-0.3 wt.%La brazing material.Microstructural characterization was con-ducted using scanning electron microscopy(SEM),energy dispersive spectroscopy(EDS),X-ray diffraction(XRD),etc.Analysis re-veals that progressive aggregation and precipitation of Cu-Sn intermetallic compounds occur with increasing Sn content,leading to microstructural coarsening.Notably,severe grain coarsening is observed when the Sn content reaches 4 wt.%.Shear testing of the BAg5CuZn-0.3 wt.%La-xSn brazing joints reveals a non-monotonic trend in joint strength:as Sn content increases,the shear strength initially improves but subsequently deteriorates after reaching an optimal value.展开更多
Metal nanoparticle(NP_S)catalysts exhibit desirable activities in various catalytic reactions.However,the sintering of metal NPs at high-temperatures even in reducing atmospheres limits its practical application.In th...Metal nanoparticle(NP_S)catalysts exhibit desirable activities in various catalytic reactions.However,the sintering of metal NPs at high-temperatures even in reducing atmospheres limits its practical application.In this work,we successfully synthesized TPA-ZSM-5 with pit-type defects by treating the ZSM-5 with tetrahydroxy ammonium hydroxide(TPAOH),which was then used as a support to prepare Ag-based and Cu-based catalysts.Stability testing results show that the Ag/TPA-ZSM-5 catalyst treated at 800℃with H_(2) could maintain the high performance in NH_(3)-SCO and the Cu/TPA-ZSM-5 catalyst treated at 900℃ with N_(2) could maintained its excellent activity in NH_(3)-SCR,however,the activities of Ag/ZSM-5 and Cu/ZSM-5 were drastically decreased or even deactivated after high-temperature treatment.In addition,a series of characterization analyses revealed that the excellent thermal stability is attribute to the presence of pit-type defects in the TPA-ZSM-5 as physical barriers to slow down or even inhibit the Ag NPs and Cu NPs sintering process.The strategy of using the pit-type defects to inhibit the sintering of metal NPs and improve the thermal stability can greatly enhance the practical application of catalysts.展开更多
Although the potential of microenvironment modulation to enhance electricity-driven CO_(2)reduction has been recognized,substantial challenges remain,particularly in effectively integrating multiple favorable microenv...Although the potential of microenvironment modulation to enhance electricity-driven CO_(2)reduction has been recognized,substantial challenges remain,particularly in effectively integrating multiple favorable microenvironments.Herein,we synthesize CeO_(2)with abundant oxygen vacancies to effectively disperse and anchor small-sized Ag_(2)O nanoparticles(Ag_(2)O/Vo-CeO_(2)).Vo-CeO_(2)acts as a multifunctional modulator,regulating both the reaction microenvironment and the electronic structure of Ag sites,thereby boosting CO_(2)reduction(CO_(2)RR)efficiency.Its strong CO_(2)adsorption and H_(2)O dissociation capabilities facilitate the supply of CO_(2)and active^(*)H species to Ag sites.The electron-withdrawing effect of VoCeO_(2)induces polarization at interfacial Ag sites,generating Agd+species that enhance CO_(2)affinity and activation.Moreover,the electronic coupling between Vo-CeO_(2)and Ag upshifts the d-band center of Ag,optimizing COOH binding and lowering the thermodynamic barrier of the potential-determining step.Ag_(2)O/Vo-CeO_(2)delivers a consistently high Faraday efficiency(FE)of over 99% for CO production even at industrially current density(up to 365 mA cm^(-2)herein),and the operational potential window spans an astonishing 1700 m V(FE>95%).The unprecedented activity,which overcomes the trade-off between the selectivity and current density for CO_(2)RR,outperforms state-of-the-art Ag-based catalysts reported to date.These findings offer a promising pathway to develop robust CO_(2)RR catalysts and present an engineering strategy for constructing the optimal microenvironment of active sites via the synergistic effects of multifunctional modulation.展开更多
To disclose the effect of contact force and electrode gap on the material transfer behavior of Ag-based contact material, arc-erosion tests of the Ag-4wt.%TiB2 contact material were performed for 5000 operations at 24...To disclose the effect of contact force and electrode gap on the material transfer behavior of Ag-based contact material, arc-erosion tests of the Ag-4wt.%TiB2 contact material were performed for 5000 operations at 24 V/16 A under resistive load on an electric contact material testing system. The arc energy and arc duration were investigated, the surface morphologies of eroded anode and cathode were characterized, the mass changes after arc-erosion tests were determined, and the material transfer behavior was discussed as well. The results show that contact force has a significant effect on the arc energy, arc duration and erosion morphology, but has no impact on the material transfer mode. However, electrode gap not only influences the arc energy, arc duration and surface morphology, but also changes the material transfer mode. At 1 mm, the material transfers from anode to cathode. Nevertheless, an opposite mode presents at 4 mm, which is from cathode to anode.展开更多
Formaldehyde is an important air pollutant and its removal is essential to protect human health and meet environmental regulations.Ag-based catalyst has a considerable potential for HCHO oxidation in low temperature r...Formaldehyde is an important air pollutant and its removal is essential to protect human health and meet environmental regulations.Ag-based catalyst has a considerable potential for HCHO oxidation in low temperature range.The valence state of Ag is one of the key roles in formaldehyde catalytic oxidation.However,its effect on activity is still ambiguous.Non-thermal plasma and conventional calcination were employed to regulate Ag valence state in this study.Three Ag-Co/CeO_(2)catalysts with totally different distribution of Ag species were obtained.A special mixed Ag valence state,~50%Ag^(δ+)with a few Ag^(0)and Ag^(+),was achieved by plasma activation.It had the merits of both good activity and stability.A close relationship between Ag valence state and the activity for HCHO oxidation was established.The activity of different Ag species follows the order:Ag^(δ+)+Ag^(0)+Ag^(+)>Ag^(δ+)>Ag^(0)>Ag^(+).展开更多
Carbon monoxide(CO)stands as one of the most valuable and economically viable products in the electrochemical reduction of CO_(2).In this study,we introduced high-surface-area porous carbon and anion-exchange ionomer ...Carbon monoxide(CO)stands as one of the most valuable and economically viable products in the electrochemical reduction of CO_(2).In this study,we introduced high-surface-area porous carbon and anion-exchange ionomer to silver nanoparticles,rapidly constructing a tri-phase interface that enhances CO_(2)transport and proton conduction.The ionomer-encapsulated tri-phase interface further improves reaction selectivity by increasing HCO_(3)^(-)concentration.Flow cell tests revealed that the 80%Ag/C catalyst doubles the partial current density of CO as compared to commercial Ag nanoparticles.To integrate the synthesized 80%Ag/C into industrial-scale membrane electrode assembly(MEA)electrolyzers(10 cm×10 cm),we developed a comprehensive evaluation system incorporating CO selectivity,cell voltage,and actual gas conversion ratio(λ_(act))with only one piece of MEA.This approach allowed systematic evaluation of current density and gas flow rate effects,followed by operational parameter optimization to 300 mA·cm^(-2)and 1000 standard cubic centimeters per minute(sccm).Under optimal conditions,the 80%Ag/C catalyst demonstrated stable operation for over 60 h with a cell voltage of 3 V.The observed CO Faradaic efficiency decay rate suggests a projected operational lifetime exceeding 500 h.This work not only presents an efficient modification strategy to enhance the CO_(2)reduction performance of silver-based catalysts,but also establishes a design-of-experiment(DOE)methodology for industrial-scale testing conditions optimization,thereby facilitating the advancement of CO_(2)reduction reaction(CO_(2)RR)toward practical industrial applications.展开更多
The pursuit of Ag-based alloys with both high strength and toughness has posed a longstanding chal-lenge.In this study,we investigated the cluster strengthening and grain refinement toughening mecha-nisms in fully oxi...The pursuit of Ag-based alloys with both high strength and toughness has posed a longstanding chal-lenge.In this study,we investigated the cluster strengthening and grain refinement toughening mecha-nisms in fully oxidized AgMgNi alloys,which were internally oxidized at 800℃ for 8 h under an oxy-gen atmosphere.We found that Mg-O clusters contributed to the hardening(138 HV)and strengthening(376.9 MPa)of the AgMg alloy through solid solution strengthening effects,albeit at the expense of duc-tility.To address this limitation,we introduced Ni nanoparticles into the AgMg alloy,resulting in signifi-cant grain refinement within its microstructure.Specifically,the grain size decreased from 67.2μm in the oxidized AgMg alloy to below 6.0μm in the oxidized AgMgNi alloy containing 0.3 wt%Ni.Consequently,the toughness increased significantly,rising from toughness value of 2177.9 MJ m^(-3) in the oxidized AgMg alloy to 6186.1 MJ m^(-3) in the oxidized AgMgNi alloy,representing a remarkable 2.8-fold enhancement.Furthermore,the internally oxidized AgMgNi alloy attained a strength of up to 387.6 MPa,comparable to that of the internally oxidized AgMg alloy,thereby demonstrating the successful realization of concurrent strengthening and toughening.These results collectively offer a novel approach for the design of high-performance alloys through the synergistic combination of cluster strengthening and grain refinement toughening.展开更多
Electrocatalytic reduction of CO_(2)to valuable products possesses huge potential to alleviate environmental and energy crisis.It is well known that Ag favors the conversion of CO_(2)to CO but the exposed active sites...Electrocatalytic reduction of CO_(2)to valuable products possesses huge potential to alleviate environmental and energy crisis.It is well known that Ag favors the conversion of CO_(2)to CO but the exposed active sites and stability are still rather limited.In this study,a novel one-dimensional Ag-based metal-organic framework(1D Ag-NIM-MOF)was successfully synthesized and used in the electrocatalytic CO_(2)reduction reaction(CO_(2)RR)for the first time.As a result,the Faradaic efficiency of CO achieved 94.5%with current density of 12.5 mA·cm^(-2)in an H-type cell and 98.2%with current density of 161 mA·cm^(-2)in a flow cell at–1.0 V(vs.RHE),which stands as a new benchmark of Ag-based MOFs in the electrocatalytic CO_(2)RR.The excellent performance of 1D Ag-NIM-MOF is attributed to its peculiar one-dimensional structure,which is beneficial for diffusion of reactants and products,and exposure of much more catalytic sites.Compared to commercial Ag nanoparticles,1D Ag-NIM-MOF exhibits superior electrocatalytic CO_(2)RR performance with higher catalytic activity and stability.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.62125402 and 62321166653).
文摘Ternary metal halides based on Cu(I)and Ag(I)have attracted intensive attention in optoelectronic applications due to their excellent luminescent properties,low toxicity,and robust stability.While the self-trapped excitons(STEs)emission mechanisms of Cu(I)halides are well understood,the STEs in Ag(I)halides remain less thoroughly explored.This study explores the STE emission efficiency within the A_(2)AgX_(3)(A=Rb,Cs;X=Cl,Br,I)system by identifying three distinct STE states in each material and calculating their configuration coordinate diagrams.We find that the STE emission efficiency in this system is mainly determined by STE stability and influenced by self-trapping and quenching barriers.Moreover,we investigate the impact of structural compactness on emission efficiency and find that the excessive electron–phonon coupling in this system can be reduced by increasing the structural compactness.The atomic packing factor is identified as a low-cost and effective descriptor for predicting STE emission efficiency in both Cs_(2)AgX_(3) and Rb_(2)AgX_(3) systems.These findings can deepen our understanding of STE behavior in metal halide materials and offer valuable insights for the design of efficient STE luminescent materials.The datasets presented in this paper are openly available in Science Data Bank at https://doi.org/10.57760/sciencedb.12094.
文摘The mechanism of interaction relation between the rare-earth element Ce and elements Pb and Bi in Ag-based filler metal has been studied. The results show that the compounds CePb and CeBi with high melting point can be easily produced between these three elements in the filler metal, which greatly limited the formation of the isolated phase Pb or Bi and also eliminated the bad effect of impurity elements Pb and Bi on the spreading property of Ag-based filler metal. The metallurgical and quantum-mechanical bond formation analysis show that a strong chemical affinity was existed between the rare-earth element Ce and impurity elements Pb and Bi, which was proved by the XRD analysis results.
基金This work is supported by the National Natural Science Foundation of China(NSFC)(Nos.21674130,51873234 and 51573039)the Natural Science Foundation of Guangdong Province(Nos.2017A030313254 and 2017A030310349)+3 种基金the Fundamental Research Funds for the Central Universities(No.171gjc02)PetroChina Innovation Foundation(No.2017D-5007-0505)Research Start-up Funds of DGUT(No.GC300501-116)Key Laboratory Opening Fund of PCFM is also gratefully acknowledged.
文摘Ag-based nano particles(NPs)catalysts have recently attracted in creasi ng atte ntion in NaBH4-assisted n itrophe nol reducti on,especially in 4?n itrophe nol(4?NP)reducti on.Moreover,Ag-based NPs catalysts are con sidered to be very promising for practical applicati ons because of their fascinating advantages,e.g.,easy preparation,relatively low cost and less toxicity,high activity and good stability.Basically,the size and shape of Ag NPs are well known as the key factors for achieving highly efficient catalytic reduction of 4-NP.In this review,three highly efficient Ag-based NPs catalysts(supported Ag NPs,anisotropic Ag NPs and bimetallic Ag NPs)are highlighted for the 4-NP reduction,in eluding the catalytic mecha nism and reactio n rate caused by their adjustments in size and shape.Although high catalytic activity has bee n demonstrated by several Ag-based NPs catalysts,further improvement in the catalytic performance is still desired.In terms of the most recent progress in Ag-based NPs catalysts for 4?NP reduction,this review provides a comprehensive assessment on the material selection,synthesis and catalytic characterizations of these catalysts.Moreover,this review aims to correlate the catalytic performance of Ag-based NPs catalysts with their size and shape,guiding the development of novel cost-effective and high-performance catalysts.
基金support by the National Basic Research Program of China (Grant No. 2007CB613901)the National Natural Science Foundation of China (Grant Nos. 50831003 and 50871062)
文摘The atomic structures of liquid Ag-based binary alloys have been investigated in the solidification process by means of X-ray diffraction. The results of liquid structure show that there is a break point in the mean nearest neighbor distance r1 and the coordination number Nmin for glass-forming liquid, while the correlation radius rc and the coordination number Nmin display a monotone variational trend above the break point. It means glass-forming liquids have a steady changing in structure above liquidus and more inhomogeneous state at liquidus. We conclude that there is a strong correlation between liquid structure and glass forming ability in Ag-based binary alloys.
基金the support from Jinhua Sanhuan Welding Materials Company LimitedSchool of Materials Science and Engineering,Nanjing University of Science and Technology.
文摘This article studies the effects of different Sn contents on the melting characteristics,microstructure,and mechanical properties of brazed joints of low-silver BAg5CuZn-0.3 wt.%La brazing material.A differential thermal analyzer(HCR-1)was used to measure the solid-liquidus temperature of BAg5CuZn-0.3 wt.%La-xSn brazing material.The results show that the addition of Sn element effect-ively reduces the solid-liquidus temperature of BAg5CuZn-0.3 wt.%La brazing material.Microstructural characterization was con-ducted using scanning electron microscopy(SEM),energy dispersive spectroscopy(EDS),X-ray diffraction(XRD),etc.Analysis re-veals that progressive aggregation and precipitation of Cu-Sn intermetallic compounds occur with increasing Sn content,leading to microstructural coarsening.Notably,severe grain coarsening is observed when the Sn content reaches 4 wt.%.Shear testing of the BAg5CuZn-0.3 wt.%La-xSn brazing joints reveals a non-monotonic trend in joint strength:as Sn content increases,the shear strength initially improves but subsequently deteriorates after reaching an optimal value.
基金supported by the National Natural Science Foundation of China(No.52370113)Yunnan Fundamental Research Projects(No.202101BE070001-001)。
文摘Metal nanoparticle(NP_S)catalysts exhibit desirable activities in various catalytic reactions.However,the sintering of metal NPs at high-temperatures even in reducing atmospheres limits its practical application.In this work,we successfully synthesized TPA-ZSM-5 with pit-type defects by treating the ZSM-5 with tetrahydroxy ammonium hydroxide(TPAOH),which was then used as a support to prepare Ag-based and Cu-based catalysts.Stability testing results show that the Ag/TPA-ZSM-5 catalyst treated at 800℃with H_(2) could maintain the high performance in NH_(3)-SCO and the Cu/TPA-ZSM-5 catalyst treated at 900℃ with N_(2) could maintained its excellent activity in NH_(3)-SCR,however,the activities of Ag/ZSM-5 and Cu/ZSM-5 were drastically decreased or even deactivated after high-temperature treatment.In addition,a series of characterization analyses revealed that the excellent thermal stability is attribute to the presence of pit-type defects in the TPA-ZSM-5 as physical barriers to slow down or even inhibit the Ag NPs and Cu NPs sintering process.The strategy of using the pit-type defects to inhibit the sintering of metal NPs and improve the thermal stability can greatly enhance the practical application of catalysts.
基金the support of this research by the Nat ional Natural Science Foundation of China(22179035)the Hei-longjiang Provincial Natural Science Foundation Joint Fund Cultivation Project(PL2024B012)the Fundamental Research Funds for the Universities of Heilongjiang Province(2023-KYYWF-1440)。
文摘Although the potential of microenvironment modulation to enhance electricity-driven CO_(2)reduction has been recognized,substantial challenges remain,particularly in effectively integrating multiple favorable microenvironments.Herein,we synthesize CeO_(2)with abundant oxygen vacancies to effectively disperse and anchor small-sized Ag_(2)O nanoparticles(Ag_(2)O/Vo-CeO_(2)).Vo-CeO_(2)acts as a multifunctional modulator,regulating both the reaction microenvironment and the electronic structure of Ag sites,thereby boosting CO_(2)reduction(CO_(2)RR)efficiency.Its strong CO_(2)adsorption and H_(2)O dissociation capabilities facilitate the supply of CO_(2)and active^(*)H species to Ag sites.The electron-withdrawing effect of VoCeO_(2)induces polarization at interfacial Ag sites,generating Agd+species that enhance CO_(2)affinity and activation.Moreover,the electronic coupling between Vo-CeO_(2)and Ag upshifts the d-band center of Ag,optimizing COOH binding and lowering the thermodynamic barrier of the potential-determining step.Ag_(2)O/Vo-CeO_(2)delivers a consistently high Faraday efficiency(FE)of over 99% for CO production even at industrially current density(up to 365 mA cm^(-2)herein),and the operational potential window spans an astonishing 1700 m V(FE>95%).The unprecedented activity,which overcomes the trade-off between the selectivity and current density for CO_(2)RR,outperforms state-of-the-art Ag-based catalysts reported to date.These findings offer a promising pathway to develop robust CO_(2)RR catalysts and present an engineering strategy for constructing the optimal microenvironment of active sites via the synergistic effects of multifunctional modulation.
基金Projects(51274163,51605146) supported by the National Natural Science Foundation of ChinaProject(U1502274) supported by Key Program of the National Natural Science Foundation of China+2 种基金Project(2018M632769) supported by the China Postdoctoral Science FoundationProject(2017SKY-WK010) supported by the Research Fund of Shaanxi Key Laboratory of Comprehensive Utilization of Tailings Resources,ChinaProject(18JK0722) supported by Special Research Program of Shaanxi Provincial Department of Education,China
文摘To disclose the effect of contact force and electrode gap on the material transfer behavior of Ag-based contact material, arc-erosion tests of the Ag-4wt.%TiB2 contact material were performed for 5000 operations at 24 V/16 A under resistive load on an electric contact material testing system. The arc energy and arc duration were investigated, the surface morphologies of eroded anode and cathode were characterized, the mass changes after arc-erosion tests were determined, and the material transfer behavior was discussed as well. The results show that contact force has a significant effect on the arc energy, arc duration and erosion morphology, but has no impact on the material transfer mode. However, electrode gap not only influences the arc energy, arc duration and surface morphology, but also changes the material transfer mode. At 1 mm, the material transfers from anode to cathode. Nevertheless, an opposite mode presents at 4 mm, which is from cathode to anode.
基金supported by the National Natural Science Foundation of China(NSFC,Nos.22006166 and 22076224)the China Postdoctoral Science Foundation(No.2019M653184)+1 种基金Guangdong Basic and Applied Basic Research Foundation(No.2020A1515010865)Fundamental Research Funds for the Central Universities(Nos.20lgjc03 and 20lgpy95)。
文摘Formaldehyde is an important air pollutant and its removal is essential to protect human health and meet environmental regulations.Ag-based catalyst has a considerable potential for HCHO oxidation in low temperature range.The valence state of Ag is one of the key roles in formaldehyde catalytic oxidation.However,its effect on activity is still ambiguous.Non-thermal plasma and conventional calcination were employed to regulate Ag valence state in this study.Three Ag-Co/CeO_(2)catalysts with totally different distribution of Ag species were obtained.A special mixed Ag valence state,~50%Ag^(δ+)with a few Ag^(0)and Ag^(+),was achieved by plasma activation.It had the merits of both good activity and stability.A close relationship between Ag valence state and the activity for HCHO oxidation was established.The activity of different Ag species follows the order:Ag^(δ+)+Ag^(0)+Ag^(+)>Ag^(δ+)>Ag^(0)>Ag^(+).
基金supported by the National Natural Science Foundation of China(No.22175127).
文摘Carbon monoxide(CO)stands as one of the most valuable and economically viable products in the electrochemical reduction of CO_(2).In this study,we introduced high-surface-area porous carbon and anion-exchange ionomer to silver nanoparticles,rapidly constructing a tri-phase interface that enhances CO_(2)transport and proton conduction.The ionomer-encapsulated tri-phase interface further improves reaction selectivity by increasing HCO_(3)^(-)concentration.Flow cell tests revealed that the 80%Ag/C catalyst doubles the partial current density of CO as compared to commercial Ag nanoparticles.To integrate the synthesized 80%Ag/C into industrial-scale membrane electrode assembly(MEA)electrolyzers(10 cm×10 cm),we developed a comprehensive evaluation system incorporating CO selectivity,cell voltage,and actual gas conversion ratio(λ_(act))with only one piece of MEA.This approach allowed systematic evaluation of current density and gas flow rate effects,followed by operational parameter optimization to 300 mA·cm^(-2)and 1000 standard cubic centimeters per minute(sccm).Under optimal conditions,the 80%Ag/C catalyst demonstrated stable operation for over 60 h with a cell voltage of 3 V.The observed CO Faradaic efficiency decay rate suggests a projected operational lifetime exceeding 500 h.This work not only presents an efficient modification strategy to enhance the CO_(2)reduction performance of silver-based catalysts,but also establishes a design-of-experiment(DOE)methodology for industrial-scale testing conditions optimization,thereby facilitating the advancement of CO_(2)reduction reaction(CO_(2)RR)toward practical industrial applications.
基金supported by the National Natural Science Foundation of China(Nos.51977027 and 51967008)the Scientific and Technological Project of Yunnan Precious Metals Lab-oratory(Nos.YPML-2023050250 and YPML-2022050206).
文摘The pursuit of Ag-based alloys with both high strength and toughness has posed a longstanding chal-lenge.In this study,we investigated the cluster strengthening and grain refinement toughening mecha-nisms in fully oxidized AgMgNi alloys,which were internally oxidized at 800℃ for 8 h under an oxy-gen atmosphere.We found that Mg-O clusters contributed to the hardening(138 HV)and strengthening(376.9 MPa)of the AgMg alloy through solid solution strengthening effects,albeit at the expense of duc-tility.To address this limitation,we introduced Ni nanoparticles into the AgMg alloy,resulting in signifi-cant grain refinement within its microstructure.Specifically,the grain size decreased from 67.2μm in the oxidized AgMg alloy to below 6.0μm in the oxidized AgMgNi alloy containing 0.3 wt%Ni.Consequently,the toughness increased significantly,rising from toughness value of 2177.9 MJ m^(-3) in the oxidized AgMg alloy to 6186.1 MJ m^(-3) in the oxidized AgMgNi alloy,representing a remarkable 2.8-fold enhancement.Furthermore,the internally oxidized AgMgNi alloy attained a strength of up to 387.6 MPa,comparable to that of the internally oxidized AgMg alloy,thereby demonstrating the successful realization of concurrent strengthening and toughening.These results collectively offer a novel approach for the design of high-performance alloys through the synergistic combination of cluster strengthening and grain refinement toughening.
基金supported by the National Natural Science Foundation of China(Nos.22172116 and 21773176)Natural Science Foundation of Hubei Province(2022CFB130).
文摘Electrocatalytic reduction of CO_(2)to valuable products possesses huge potential to alleviate environmental and energy crisis.It is well known that Ag favors the conversion of CO_(2)to CO but the exposed active sites and stability are still rather limited.In this study,a novel one-dimensional Ag-based metal-organic framework(1D Ag-NIM-MOF)was successfully synthesized and used in the electrocatalytic CO_(2)reduction reaction(CO_(2)RR)for the first time.As a result,the Faradaic efficiency of CO achieved 94.5%with current density of 12.5 mA·cm^(-2)in an H-type cell and 98.2%with current density of 161 mA·cm^(-2)in a flow cell at–1.0 V(vs.RHE),which stands as a new benchmark of Ag-based MOFs in the electrocatalytic CO_(2)RR.The excellent performance of 1D Ag-NIM-MOF is attributed to its peculiar one-dimensional structure,which is beneficial for diffusion of reactants and products,and exposure of much more catalytic sites.Compared to commercial Ag nanoparticles,1D Ag-NIM-MOF exhibits superior electrocatalytic CO_(2)RR performance with higher catalytic activity and stability.
