With the large-scale service of lithium-ion batteries(LIBs),their failures have attracted significant attentions.While the decay of active materials is the primary cause for LIB failures,the degradation of auxiliary m...With the large-scale service of lithium-ion batteries(LIBs),their failures have attracted significant attentions.While the decay of active materials is the primary cause for LIB failures,the degradation of auxiliary materials,such as current collector corrosion,should not be disregarded.Therefore,it is necessary to conduct a comprehensive review in this field.In this review,from the perspectives of electrochemistry and materials,we systematically summarize the corrosion behavior of aluminum cathode current collector and propose corresponding countermeasures.Firstly,the corrosion type is clarified based on the properties of passivation layers in different organic electrolyte components.Furthermore,a thoroughgoing analysis is presented to examine the impact of various factors on aluminum corrosion,including lithium salts,organic solvents,water impurities,and operating conditions.Subsequently,strategies for electrolyte and protection layer employed to suppress corrosion are discussed in detail.Lastly and most importantly,we provide insights and recommendations to prevent corrosion of current collectors,facilitate the development of advanced current collectors and the implementation of next-generation high-voltage stable LIBs.展开更多
Objective: To evaluate the efficacy and safety of patient-controlled analgesia(PCA) with hydromorphone as perioperative analgesia during uterine artery embolization(UAE) via the right radial artery.Patients and method...Objective: To evaluate the efficacy and safety of patient-controlled analgesia(PCA) with hydromorphone as perioperative analgesia during uterine artery embolization(UAE) via the right radial artery.Patients and methods: A total of 33 patients with uterine fibroids, who underwent UAE at the authors’ hospital between June 2021 and March 2022, were selected. Hydromorphone(10 mg) was dispensed into a 100 ml PCA pump with normal saline. Pump administration was initiated 15 min before the start of the procedure, and the intraoperative dose was adjusted according to patient pain level. A numerical rating scale was used to evaluate pain immediately after embolization, 5 min after embolization, at the end of the procedure, and 6, 12, 24, 48, and 72 h after the procedure. Side effects were also observed.Results: Thirty-three patients underwent uterine artery embolization via the right radial artery. Patient pain was well controlled at all time points surveyed, and patients reported satisfaction with analgesia. The median length of hospital stay was 5 days. There were 7 cases of adverse reactions, but no serious side effects were observed.Conclusion: Patients reported positive experiences with arterial embolization of uterine fibroids via the right radial artery. Hydromorphone PCA effectively controlled pain. The PCA pump is easy to operate, has a low incidence of adverse reactions, and offers economic benefits at the patient and institutional levels.展开更多
The antiknock capability and thermal protection performance of rescue capsules mainly depend on the structural design of the cabin.By designing a new type of cabin structure,it can resist the impact of explosion shock...The antiknock capability and thermal protection performance of rescue capsules mainly depend on the structural design of the cabin.By designing a new type of cabin structure,it can resist the impact of explosion shock waves and thermal shocks.In this paper,a new honeycomb-like cabin is proposed;the model has a novel thermal insulation layer design.Then,the antiknock capabilities and thermal protection analysis are carried out by using computer software.The“Autodyn”analysis module in ANSYS Workbench 17.0 has been used to simulate the explosion of TNT with a certain quality in a single room.The pressure map over time and the pressure variation curve at different locations for a single room are obtained.Through the analysis module“Transient Structural,”the stress and deformation of the honeycomb-like cabin under the blast load are simulated.The“Transient Thermal”analysis module in the finite element software is used to conduct a transient thermal analysis on the cabin structure.The temperature map and the temperature rise curve of each layer of the cabin cases are obtained.The analysis results indicate that the honeycomb-like cabin design has a good antiknock capability and thermal protection performance,and it can meet the usage requirements of the rescue capsule under dangerous conditions.展开更多
Based on the attributes of nonflammability,environmental benignity,and cost-effectiveness of aqueous electrolytes,as well as the favorable compatibility of zinc metal with them,aqueous zinc ions batteries(AZIBs)become...Based on the attributes of nonflammability,environmental benignity,and cost-effectiveness of aqueous electrolytes,as well as the favorable compatibility of zinc metal with them,aqueous zinc ions batteries(AZIBs)become the leading energy storage candidate to meet the requirements of safety and low cost.Yet,aqueous electrolytes,acting as a double-edged sword,also play a negative role by directly or indirectly causing various parasitic reactions at the zinc anode side.These reactions include hydrogen evolution reaction,passivation,and dendrites,resulting in poor Coulombic efficiency and short lifespan of AZIBs.A comprehensive review of aqueous electrolytes chemistry,zinc chemistry,mechanism and chemistry of parasitic reactions,and their relationship is lacking.Moreover,the understanding of strategies for suppressing parasitic reactions from an electrochemical perspective is not profound enough.In this review,firstly,the chemistry of electrolytes,zinc anodes,and parasitic reactions and their relationship in AZIBs are deeply disclosed.Subsequently,the strategies for suppressing parasitic reactions from the perspective of enhancing the inherent thermodynamic stability of electrolytes and anodes,and lowering the dynamics of parasitic reactions at Zn/electrolyte interfaces are reviewed.Lastly,the perspectives on the future development direction of aqueous electrolytes,zinc anodes,and Zn/electrolyte interfaces are presented.展开更多
Photocatalysis shows great promise in the field of solar energy conversion.One of the reasons for this is because it promotes the development of multi-field-coupled catalysis.In order to explore the principles of mult...Photocatalysis shows great promise in the field of solar energy conversion.One of the reasons for this is because it promotes the development of multi-field-coupled catalysis.In order to explore the principles of multi-field-coupled catalytic reactions,an in situ multi-field-coupled characterization technique is required.In this study,we obtained hydrogenated ST-01 TiO2 and observed enhanced catalytic activity by thermal coupled photocatalysis.In situ photoconductivity was employed to understand the activity enhancement.The effects of the reaction temperature,reaction atmosphere,and oxygen vacancy(Ov)on the photoconductivity of TiO2 were studied.After coupling thermal into photoconductivity measurement,highly active Ov-TiO2 displayed rapid decay of photoconductivity in a CO2 atmosphere and slow decay of photoconductivity in a N2 atmosphere.These phenomena revealed that photothermal coupling assisted the detrapping of electrons at the Ov surface and promoted electron transfer to CO2,which clearly explained the high photothermal catalytic activity of Ov-TiO2.This study demonstrated that photoconductivity is a useful tool to help understand photothermal catalytic phenomena.展开更多
Semiconductor oxides are widely used to achieve photocatalytic removal of NOx(NO and NO2) species. These materials also exhibit enhanced oxidation ability in thermally assisted photocatalysis;however, many of them ten...Semiconductor oxides are widely used to achieve photocatalytic removal of NOx(NO and NO2) species. These materials also exhibit enhanced oxidation ability in thermally assisted photocatalysis;however, many of them tend to be deactivated at high relative humidity(RH) levels. In the case of the benchmark P25 TiO2 photocatalyst, we observe a significant decrease in non-NO2 selectivity from 95.02% to 58.33% when RH increases from 20% to 80%. Interestingly, the porous TiO2(B) microspheres synthesized in this work exhibit 99% selectivity at 20% RH;the selectivity remains as high as 96.18% at 80% RH. The high humidity tolerance of the TiO2(B) sample can be ascribed to its strong water desorption capacity and easy O2 adsorption at elevated temperatures, which reflects the fact that the superoxide radical is the main active species for the deep oxidation of NOx. This work may inspire the design of efficient photothermal catalysts with application in NOx removal in hot and humid environments.展开更多
The stress corrosion cracking(SCC) susceptibility of 2297 Al-Li alloy in 1 M Na Cl +0.01 M H2O2 solution(CP solution) and 1 M NaCl + 0.01 M H2O2+ 0.6 M Na2SO4 solution(CPS solution) was investigated by slow-strain rat...The stress corrosion cracking(SCC) susceptibility of 2297 Al-Li alloy in 1 M Na Cl +0.01 M H2O2 solution(CP solution) and 1 M NaCl + 0.01 M H2O2+ 0.6 M Na2SO4 solution(CPS solution) was investigated by slow-strain rate tests at various strain rates ranging from 10-5s(-1) to 10-7s-1. The roles of H2O2 and SO42-in the corrosion process were estimated by potentiodynamic polarization and electrochemical impedance spectroscopy. 2297 Al-Li alloy does not fracture ascribed to SCC in CP solution, while it undergoes SCC in CPS solution. In CPS solution,with a decreasing strain rate from 10-5s(-1) to 10-7s-1, the SCC susceptibility firstly rises and then declines exhibiting a peak value at a strain rate of 10-6s-1. H2O2 promotes the active dissolution while SO42- lowers the corrosion rate. The SCC fracture is associated with a decline in the dissolution rate of the crack tip by SO42-, which leads to stress concentration. In CPS solution, a reduction in the local dissolution rate of the crack tip leads to stress concentration, resulting in SCC fracture.As the preferred initiation site for a crack, pits also show a noteworthy effect on SCC of 2297 Al-Li alloy.展开更多
The stress corrosion cracking(SCC) behavior and mechanism of 7050-T7451 aluminum alloy under wet-dry cyclic conditions were investigated. Slow strain rate tests(SSRTs) and electrochemical tests were used to study the ...The stress corrosion cracking(SCC) behavior and mechanism of 7050-T7451 aluminum alloy under wet-dry cyclic conditions were investigated. Slow strain rate tests(SSRTs) and electrochemical tests were used to study the effects of dry/wet ratio(DWR) and pre-immersion on SCC.Fracture and side surface characterizations were observed by scanning electron microscopy(SEM).The results demonstrate that SCC susceptibility decreases with an increase of the DWR. With an increase of the pre-immersion time, both continuous pre-immersion(CP) and wet-dry cyclic preimmersion(WDP) samples are more sensitive to SCC, and the cracking mode in the SCC fracture region is intergranular. Furthermore, the effect of WDP on SCC is greater than that of CP when the total time immersed in solution before an SSRT is the same with each other. In fact, each single wetdry cycle can be divided into three processes with respect to the change of solution on samples’ surface. Volatilization of water on the surface results in an increase in solute concentration, thus accelerating corrosion.展开更多
Although platinum nanocrystals have been considered as potential electrocatalysts for methanol oxidation reaction(MOR)in fuel cells,the large-scale practical implementation has been stagnated by their limited abundanc...Although platinum nanocrystals have been considered as potential electrocatalysts for methanol oxidation reaction(MOR)in fuel cells,the large-scale practical implementation has been stagnated by their limited abundance,easy poisoning,and low durability.Here,grain boundary-enriched platinum(GB-Pt)scaffolds are produced in large scale via facilely reducing fast cryomediated dynamic equilibrium hydrolysates of platinum salts.Such plentiful platinum grain boundaries are originated from the fast fusion of short platinum nanowires during reduction of the individually and homogeneously dispersed platinum intermediates.These grain boundaries can provide abundant active sites to efficiently catalyze MOR and meanwhile enable to oxidize the adsorbed poisonous CO during the electrocatalytic process.As a consequence,the as-synthesized GB-Pt scaffolds exhibit an impressively high mass activity of 1027.1 mA mgPt^(−1) for MOR,much higher than that of commercial Pt/C(345.2 mA mgPt^(−1)),as well as good stability up to 5000 cycles.We are confident that this synthetic protocol can be further extended to synthesize various grain boundary-enriched metal scaffolds with broad applications in catalysis.展开更多
The bimodal grain size metals show improved strength and ductility compared to traditional metals; however, their corrosion properties are unknown. In order to evaluate the corrosion properties of these metals, the bi...The bimodal grain size metals show improved strength and ductility compared to traditional metals; however, their corrosion properties are unknown. In order to evaluate the corrosion properties of these metals, the bimodal grain size 7075 aviation aluminum alloys containing different ratios of coarse（100 μm in diameter） and fine（10 μm in diameter） grains were prepared by spark plasma sintering（SPS）. The effects of grain size as well as the mixture degree of coarse and fine grains on general corrosion were estimated by immersion tests, electrochemical measurements and complementary techniques such as scanning electron microscope（SEM） and transmission electron microscope-energy disperse spectroscopy（TEM-EDS）. The results show that, compared to fine grains, the coarse grains have a faster dissolution rate in acidic NaCl solution due to the bigger size,higher alloying elements content and larger area fraction of second phases in them. In coarse grains,the hydrogen ions have a faster reduction rate on cathodic second phases, therefore promoting the corrosion propagation. The mixture of coarse and fine grains also increases the electrochemical heterogeneity of alloys in micro-scale, and thus the increased mixture degree of these grains in metal matrix accelerates the corrosion rate of alloys in acidic NaCl solution.展开更多
Photothermal CO_(2)reduction with H2O,integrating advantages of photocatalysis driven H2O splitting and thermal catalysis promoted CO_(2)reduction,has drawn sharply increasing attention in artificial synthesis of sola...Photothermal CO_(2)reduction with H2O,integrating advantages of photocatalysis driven H2O splitting and thermal catalysis promoted CO_(2)reduction,has drawn sharply increasing attention in artificial synthesis of solar fuels.The photothermal effect of metal nanoparticles facilities CO_(2)hydrogenation and activation of lattice oxygen in oxide photocatalyst promotes H2O oxidation,which is essentially considered for highly efficient photothermal catalysis.However,the large thermal conductivity of most metal nanoparticles induces inevitable heat dissipation,restricting the increase of catalyst temperature.In this work,to minimize the heat dissipation,we employ bismuth nanoparticles as photothermal unit,which is of the lowest thermal conductivity in the metal family.Meanwhile,we adopt bismuth doped NaTaO_(3)as photocatalytic unit because of the bismuth doping induced activation of lattice oxygen.The bismuth nanoparticles are assembled with bismuth doped NaTaO_(3)through one-step tunable transformation from Bi4TaO8Cl.Benefiting from the photothermal effect,thermal insulation caused by bismuth metal,and lattice oxygen activation by bismuth doping,the NaTaO_(3):Bi hybrid exhibits high photothermal catalytic performance.The yield of CO over NaTaO_(3):Bi hybrid at 413 K via photothermal catalysis is 141 times higher than that room temperature photocatalysis.Further,ultraviolet(UV)light irradiation leads to 89.2%selectivity of CO and visible light irradiation leads to 97.5%selectivity of CH4.This work may broaden the photocatalytic application of ABO_(3)perovskite and provides a novel strategy for the development of photothermal catalysts for artificial photosynthesis.展开更多
The structure and mechanical property of Dabryanus scale were investigated. Environmental Scanning Electron Micros- copy （ESEM） and Transmission Electron Microscopy （TEM） were used to observe the scale structure. ...The structure and mechanical property of Dabryanus scale were investigated. Environmental Scanning Electron Micros- copy （ESEM） and Transmission Electron Microscopy （TEM） were used to observe the scale structure. The scale has a discrete osseous layer which is composed of boat-like unit （due to the shape）. The osseous layer is embedded into fibrillary layer, and the largest thickness ratio of osseous layer to fibrillary layer is about 7, much higher than those of other reported fish scales. Nanoindentation test was used to investigate mechanical property of the scale. Elastic modulus （E,） and hardness （H） of Dabryanus scale are much lower than those of other reported fish scales. Scale models were proposed and the principles of materials mechanics were used to analyze the mechanical properties of the Dabryanus scale. The boat-like unit in osseous layer makes the scale flexible while keeping a high thickness ratio of osseous layer to fibrillary layer, which increases the flexibility and protection capacity of the scale This study may provide new strategy for the design of flexible armor or flexible devices.展开更多
文摘With the large-scale service of lithium-ion batteries(LIBs),their failures have attracted significant attentions.While the decay of active materials is the primary cause for LIB failures,the degradation of auxiliary materials,such as current collector corrosion,should not be disregarded.Therefore,it is necessary to conduct a comprehensive review in this field.In this review,from the perspectives of electrochemistry and materials,we systematically summarize the corrosion behavior of aluminum cathode current collector and propose corresponding countermeasures.Firstly,the corrosion type is clarified based on the properties of passivation layers in different organic electrolyte components.Furthermore,a thoroughgoing analysis is presented to examine the impact of various factors on aluminum corrosion,including lithium salts,organic solvents,water impurities,and operating conditions.Subsequently,strategies for electrolyte and protection layer employed to suppress corrosion are discussed in detail.Lastly and most importantly,we provide insights and recommendations to prevent corrosion of current collectors,facilitate the development of advanced current collectors and the implementation of next-generation high-voltage stable LIBs.
文摘Objective: To evaluate the efficacy and safety of patient-controlled analgesia(PCA) with hydromorphone as perioperative analgesia during uterine artery embolization(UAE) via the right radial artery.Patients and methods: A total of 33 patients with uterine fibroids, who underwent UAE at the authors’ hospital between June 2021 and March 2022, were selected. Hydromorphone(10 mg) was dispensed into a 100 ml PCA pump with normal saline. Pump administration was initiated 15 min before the start of the procedure, and the intraoperative dose was adjusted according to patient pain level. A numerical rating scale was used to evaluate pain immediately after embolization, 5 min after embolization, at the end of the procedure, and 6, 12, 24, 48, and 72 h after the procedure. Side effects were also observed.Results: Thirty-three patients underwent uterine artery embolization via the right radial artery. Patient pain was well controlled at all time points surveyed, and patients reported satisfaction with analgesia. The median length of hospital stay was 5 days. There were 7 cases of adverse reactions, but no serious side effects were observed.Conclusion: Patients reported positive experiences with arterial embolization of uterine fibroids via the right radial artery. Hydromorphone PCA effectively controlled pain. The PCA pump is easy to operate, has a low incidence of adverse reactions, and offers economic benefits at the patient and institutional levels.
基金This article was funded by the project(no.51674149)supported by National Natural Science Foundation of China.The authors wish to acknowledge the support。
文摘The antiknock capability and thermal protection performance of rescue capsules mainly depend on the structural design of the cabin.By designing a new type of cabin structure,it can resist the impact of explosion shock waves and thermal shocks.In this paper,a new honeycomb-like cabin is proposed;the model has a novel thermal insulation layer design.Then,the antiknock capabilities and thermal protection analysis are carried out by using computer software.The“Autodyn”analysis module in ANSYS Workbench 17.0 has been used to simulate the explosion of TNT with a certain quality in a single room.The pressure map over time and the pressure variation curve at different locations for a single room are obtained.Through the analysis module“Transient Structural,”the stress and deformation of the honeycomb-like cabin under the blast load are simulated.The“Transient Thermal”analysis module in the finite element software is used to conduct a transient thermal analysis on the cabin structure.The temperature map and the temperature rise curve of each layer of the cabin cases are obtained.The analysis results indicate that the honeycomb-like cabin design has a good antiknock capability and thermal protection performance,and it can meet the usage requirements of the rescue capsule under dangerous conditions.
基金supported by the Academic Excellence Foundation of BUAA for PhD Studentsthe National Natural Science Foundation of China (Grant Number: 52001016)
文摘Based on the attributes of nonflammability,environmental benignity,and cost-effectiveness of aqueous electrolytes,as well as the favorable compatibility of zinc metal with them,aqueous zinc ions batteries(AZIBs)become the leading energy storage candidate to meet the requirements of safety and low cost.Yet,aqueous electrolytes,acting as a double-edged sword,also play a negative role by directly or indirectly causing various parasitic reactions at the zinc anode side.These reactions include hydrogen evolution reaction,passivation,and dendrites,resulting in poor Coulombic efficiency and short lifespan of AZIBs.A comprehensive review of aqueous electrolytes chemistry,zinc chemistry,mechanism and chemistry of parasitic reactions,and their relationship is lacking.Moreover,the understanding of strategies for suppressing parasitic reactions from an electrochemical perspective is not profound enough.In this review,firstly,the chemistry of electrolytes,zinc anodes,and parasitic reactions and their relationship in AZIBs are deeply disclosed.Subsequently,the strategies for suppressing parasitic reactions from the perspective of enhancing the inherent thermodynamic stability of electrolytes and anodes,and lowering the dynamics of parasitic reactions at Zn/electrolyte interfaces are reviewed.Lastly,the perspectives on the future development direction of aqueous electrolytes,zinc anodes,and Zn/electrolyte interfaces are presented.
基金supported by the Natural Science Foundation of China(51072032,51372036,51102001)the Key Project of Chinese Ministry of Education(113020A)+1 种基金the 111 project(B13013)Jilin Province Science and Technology Development Plan(20180101175JC,20160520170JH)~~
文摘Photocatalysis shows great promise in the field of solar energy conversion.One of the reasons for this is because it promotes the development of multi-field-coupled catalysis.In order to explore the principles of multi-field-coupled catalytic reactions,an in situ multi-field-coupled characterization technique is required.In this study,we obtained hydrogenated ST-01 TiO2 and observed enhanced catalytic activity by thermal coupled photocatalysis.In situ photoconductivity was employed to understand the activity enhancement.The effects of the reaction temperature,reaction atmosphere,and oxygen vacancy(Ov)on the photoconductivity of TiO2 were studied.After coupling thermal into photoconductivity measurement,highly active Ov-TiO2 displayed rapid decay of photoconductivity in a CO2 atmosphere and slow decay of photoconductivity in a N2 atmosphere.These phenomena revealed that photothermal coupling assisted the detrapping of electrons at the Ov surface and promoted electron transfer to CO2,which clearly explained the high photothermal catalytic activity of Ov-TiO2.This study demonstrated that photoconductivity is a useful tool to help understand photothermal catalytic phenomena.
文摘Semiconductor oxides are widely used to achieve photocatalytic removal of NOx(NO and NO2) species. These materials also exhibit enhanced oxidation ability in thermally assisted photocatalysis;however, many of them tend to be deactivated at high relative humidity(RH) levels. In the case of the benchmark P25 TiO2 photocatalyst, we observe a significant decrease in non-NO2 selectivity from 95.02% to 58.33% when RH increases from 20% to 80%. Interestingly, the porous TiO2(B) microspheres synthesized in this work exhibit 99% selectivity at 20% RH;the selectivity remains as high as 96.18% at 80% RH. The high humidity tolerance of the TiO2(B) sample can be ascribed to its strong water desorption capacity and easy O2 adsorption at elevated temperatures, which reflects the fact that the superoxide radical is the main active species for the deep oxidation of NOx. This work may inspire the design of efficient photothermal catalysts with application in NOx removal in hot and humid environments.
基金co-supported by the National Nature Science Foundations of China (No. 51671013)Beijing Nova Program of China (No. Z161100004916061)
文摘The stress corrosion cracking(SCC) susceptibility of 2297 Al-Li alloy in 1 M Na Cl +0.01 M H2O2 solution(CP solution) and 1 M NaCl + 0.01 M H2O2+ 0.6 M Na2SO4 solution(CPS solution) was investigated by slow-strain rate tests at various strain rates ranging from 10-5s(-1) to 10-7s-1. The roles of H2O2 and SO42-in the corrosion process were estimated by potentiodynamic polarization and electrochemical impedance spectroscopy. 2297 Al-Li alloy does not fracture ascribed to SCC in CP solution, while it undergoes SCC in CPS solution. In CPS solution,with a decreasing strain rate from 10-5s(-1) to 10-7s-1, the SCC susceptibility firstly rises and then declines exhibiting a peak value at a strain rate of 10-6s-1. H2O2 promotes the active dissolution while SO42- lowers the corrosion rate. The SCC fracture is associated with a decline in the dissolution rate of the crack tip by SO42-, which leads to stress concentration. In CPS solution, a reduction in the local dissolution rate of the crack tip leads to stress concentration, resulting in SCC fracture.As the preferred initiation site for a crack, pits also show a noteworthy effect on SCC of 2297 Al-Li alloy.
基金co-supported by the National Natural Science Foundation of China (No. 51671013)the Beijing Nova Program of China (No. Z161100004916061)
文摘The stress corrosion cracking(SCC) behavior and mechanism of 7050-T7451 aluminum alloy under wet-dry cyclic conditions were investigated. Slow strain rate tests(SSRTs) and electrochemical tests were used to study the effects of dry/wet ratio(DWR) and pre-immersion on SCC.Fracture and side surface characterizations were observed by scanning electron microscopy(SEM).The results demonstrate that SCC susceptibility decreases with an increase of the DWR. With an increase of the pre-immersion time, both continuous pre-immersion(CP) and wet-dry cyclic preimmersion(WDP) samples are more sensitive to SCC, and the cracking mode in the SCC fracture region is intergranular. Furthermore, the effect of WDP on SCC is greater than that of CP when the total time immersed in solution before an SSRT is the same with each other. In fact, each single wetdry cycle can be divided into three processes with respect to the change of solution on samples’ surface. Volatilization of water on the surface results in an increase in solute concentration, thus accelerating corrosion.
基金This work was financially supported by the National Science Foundation of China(Nos.51622203 and 51572007),“Recruitment Program of Global Experts.”。
文摘Although platinum nanocrystals have been considered as potential electrocatalysts for methanol oxidation reaction(MOR)in fuel cells,the large-scale practical implementation has been stagnated by their limited abundance,easy poisoning,and low durability.Here,grain boundary-enriched platinum(GB-Pt)scaffolds are produced in large scale via facilely reducing fast cryomediated dynamic equilibrium hydrolysates of platinum salts.Such plentiful platinum grain boundaries are originated from the fast fusion of short platinum nanowires during reduction of the individually and homogeneously dispersed platinum intermediates.These grain boundaries can provide abundant active sites to efficiently catalyze MOR and meanwhile enable to oxidize the adsorbed poisonous CO during the electrocatalytic process.As a consequence,the as-synthesized GB-Pt scaffolds exhibit an impressively high mass activity of 1027.1 mA mgPt^(−1) for MOR,much higher than that of commercial Pt/C(345.2 mA mgPt^(−1)),as well as good stability up to 5000 cycles.We are confident that this synthetic protocol can be further extended to synthesize various grain boundary-enriched metal scaffolds with broad applications in catalysis.
基金supported by the Innovation Foundation of BUAA for PhD Graduatesthe National Natural Science Foundation of China (NSFC) under Grant No.51271012
文摘The bimodal grain size metals show improved strength and ductility compared to traditional metals; however, their corrosion properties are unknown. In order to evaluate the corrosion properties of these metals, the bimodal grain size 7075 aviation aluminum alloys containing different ratios of coarse（100 μm in diameter） and fine（10 μm in diameter） grains were prepared by spark plasma sintering（SPS）. The effects of grain size as well as the mixture degree of coarse and fine grains on general corrosion were estimated by immersion tests, electrochemical measurements and complementary techniques such as scanning electron microscope（SEM） and transmission electron microscope-energy disperse spectroscopy（TEM-EDS）. The results show that, compared to fine grains, the coarse grains have a faster dissolution rate in acidic NaCl solution due to the bigger size,higher alloying elements content and larger area fraction of second phases in them. In coarse grains,the hydrogen ions have a faster reduction rate on cathodic second phases, therefore promoting the corrosion propagation. The mixture of coarse and fine grains also increases the electrochemical heterogeneity of alloys in micro-scale, and thus the increased mixture degree of these grains in metal matrix accelerates the corrosion rate of alloys in acidic NaCl solution.
基金supported by the Natural Science Foundation of China(Nos.91833303,52273236,and 51872044)the 111 Project(No.B13013)Jilin Province Science and Technology Development Project(No.20220201073GX).
文摘Photothermal CO_(2)reduction with H2O,integrating advantages of photocatalysis driven H2O splitting and thermal catalysis promoted CO_(2)reduction,has drawn sharply increasing attention in artificial synthesis of solar fuels.The photothermal effect of metal nanoparticles facilities CO_(2)hydrogenation and activation of lattice oxygen in oxide photocatalyst promotes H2O oxidation,which is essentially considered for highly efficient photothermal catalysis.However,the large thermal conductivity of most metal nanoparticles induces inevitable heat dissipation,restricting the increase of catalyst temperature.In this work,to minimize the heat dissipation,we employ bismuth nanoparticles as photothermal unit,which is of the lowest thermal conductivity in the metal family.Meanwhile,we adopt bismuth doped NaTaO_(3)as photocatalytic unit because of the bismuth doping induced activation of lattice oxygen.The bismuth nanoparticles are assembled with bismuth doped NaTaO_(3)through one-step tunable transformation from Bi4TaO8Cl.Benefiting from the photothermal effect,thermal insulation caused by bismuth metal,and lattice oxygen activation by bismuth doping,the NaTaO_(3):Bi hybrid exhibits high photothermal catalytic performance.The yield of CO over NaTaO_(3):Bi hybrid at 413 K via photothermal catalysis is 141 times higher than that room temperature photocatalysis.Further,ultraviolet(UV)light irradiation leads to 89.2%selectivity of CO and visible light irradiation leads to 97.5%selectivity of CH4.This work may broaden the photocatalytic application of ABO_(3)perovskite and provides a novel strategy for the development of photothermal catalysts for artificial photosynthesis.
基金the financial support from the National Natural Science Foundation of China （No. 21371019）.
文摘The structure and mechanical property of Dabryanus scale were investigated. Environmental Scanning Electron Micros- copy （ESEM） and Transmission Electron Microscopy （TEM） were used to observe the scale structure. The scale has a discrete osseous layer which is composed of boat-like unit （due to the shape）. The osseous layer is embedded into fibrillary layer, and the largest thickness ratio of osseous layer to fibrillary layer is about 7, much higher than those of other reported fish scales. Nanoindentation test was used to investigate mechanical property of the scale. Elastic modulus （E,） and hardness （H） of Dabryanus scale are much lower than those of other reported fish scales. Scale models were proposed and the principles of materials mechanics were used to analyze the mechanical properties of the Dabryanus scale. The boat-like unit in osseous layer makes the scale flexible while keeping a high thickness ratio of osseous layer to fibrillary layer, which increases the flexibility and protection capacity of the scale This study may provide new strategy for the design of flexible armor or flexible devices.
