The damage characteristics of different speed sections of Cu−Cr−Zr alloy rail after simulated launch were studied.The microstructure,morphologies and properties of samples were investigated by using XRD,XPS,EBSD,SEM,h...The damage characteristics of different speed sections of Cu−Cr−Zr alloy rail after simulated launch were studied.The microstructure,morphologies and properties of samples were investigated by using XRD,XPS,EBSD,SEM,hardness test,electrochemical test and DSC techniques.It was found that deposition layers were formed on the surfaces of the simulated launch samples.The thickness and surface roughness of these deposition layers increased with increasing the heat effect,suggesting a launch speed dependent damage degree of the arc ablation.The hardness variation of samples is attributed to the effects of the deposition layer and deformation hardening.The surface deposition layer affects corrosion resistance and crystalline characteristics,leading to changes in subsequent service performances.Additionally,the surface texture and plastic deformation ability of the samples are related to the recrystallization degree and deformation grain amount.展开更多
Developing Cu single-atom catalysts(SACs)with well-defined active sites is highly desirable for producing CH4 in the electrochemical CO_(2) reduction reaction and understanding the structure-property relationship.Here...Developing Cu single-atom catalysts(SACs)with well-defined active sites is highly desirable for producing CH4 in the electrochemical CO_(2) reduction reaction and understanding the structure-property relationship.Herein,a new graphdiyne analogue with uniformly distributed N_(2)-bidentate(note that N_(2)-bidentate site=N^N-bidentate site;N_(2)≠dinitrogen gas in this work)sites are synthesized.Due to the strong interaction between Cu and the N_(2)-bidentate site,a Cu SAC with isolated undercoordinated Cu-N_(2) sites(Cu1.0/N_(2)-GDY)is obtained,with the Cu loading of 1.0 wt%.Cu1.0/N_(2)-GDY exhibits the highest Faradaic efficiency(FE)of 80.6% for CH_(4) in electrocatalytic reduction of CO_(2) at-0.96 V vs.RHE,and the partial current density of CH_(4) is 160 mA cm^(-2).The selectivity for CH_(4) is maintained above 70% when the total current density is 100 to 300 mA cm^(-2).More remarkably,the Cu1.0/N_(2)-GDY achieves a mass activity of 53.2 A/mgCu toward CH4 under-1.18 V vs.RHE.In situ electrochemical spectroscopic studies reveal that undercoordinated Cu-N_(2) sites are more favorable in generating key ^(*)COOH and ^(*)CHO intermediate than Cu nanoparticle counterparts.This work provides an effective pathway to produce SACs with undercoordinated Metal-N_(2) sites toward efficient electrocatalysis.展开更多
MoS_(2)/CuS composite catalysts were successfully synthesized using a one-step hydrothermal method with sodium molybdate dihydrate,thiourea,oxalic acid,and copper nitrate trihydrate as raw materials.The hydrogen pro-d...MoS_(2)/CuS composite catalysts were successfully synthesized using a one-step hydrothermal method with sodium molybdate dihydrate,thiourea,oxalic acid,and copper nitrate trihydrate as raw materials.The hydrogen pro-duction performance of MoS_(2)/CuS prepared with different molar ratios of Mo to Cu precursors(n_(Mo)∶n_(Cu))as cathodic catalysts was investigated in the two-chamber microbial electrolytic cell(MEC).X-ray diffraction(XRD),X-ray pho-toelectron spectroscopy(XPS),scanning electron microscopy(SEM),transmission electron microscope(TEM),linear scanning voltammetry(LSV),electrochemical impedance analysis(EIS),and cyclic voltammetry(CV)were used to characterize the synthesized catalysts for testing and analyzing the hydrogen-producing performance.The results showed that the hydrogen evolution performance of MoS_(2)/CuS-20%(nMo∶nCu=5∶1)was better than that of platinum(Pt)mesh,and the hydrogen production rate of MoS_(2)/CuS-20%as a cathode in MEC was(0.2031±0.0237)m^(3)_(H_(2))·m^(-3)·d^(-1) for 72 h at an applied voltage of 0.8 V,which was slightly higher than that of Pt mesh of(0.1886±0.0134)m^(3)_(H_(2))·m^(-3)·d^(-1).The addition of a certain amount of CuS not only regulates the electron transfer ability of MoS_(2) but also increases the density of active sites.展开更多
The nature and distribution of Cu species in Cu-SSZ-13 play a vital role in selective catalytic reduction of NO by NH3(NH3-SCR),but existing methods for adjusting the Cu distribution are complex and difficult to contr...The nature and distribution of Cu species in Cu-SSZ-13 play a vital role in selective catalytic reduction of NO by NH3(NH3-SCR),but existing methods for adjusting the Cu distribution are complex and difficult to control.Herein,we report a simple and effective ion-exchange approach to regulate the Cu distribution in the one-pot synthesized Cu-SSZ-13 that possesses sufficient initial Cu species and thus provides a“natural environment”for adjusting Cu distribution precisely.By using this proposed strategy,a series of Cu-SSZ-13x zeolites with different Cu contents and distributions were obtained.It is shown that the dealumination of the as-synthesized Cu-SSZ-13 during the ion-exchange generates abundant vacant sites in the double six-membered-rings of the SSZ-13 zeolite for relocating Cu2+species and thus allows the redistribution of the Cu species.The catalytic results showed that the ion-exchanged Cu-SSZ-13 zeolites exhibit quite different catalytic performance in NH3-SCR reaction but superior to the parent counterpart.The structure–activity relationship analysis indicates that the redistribution of Cu species rather than other factors(e.g.,crystallinity,chemical composition,and porous structure)is responsible for the improved NH3-SCR performance and SO_(2) and H_(2)O resistance.Our work offers an effective method to precisely adjust the Cu distribution in preparing the industrial SCR catalysts.展开更多
Cu-based catalysts have been extensively used in methanol steam reforming(MSR)reactions because of their low cost and high effi ciency.ZnO is often used in commercial Cu-based catalysts as both a structural and an ele...Cu-based catalysts have been extensively used in methanol steam reforming(MSR)reactions because of their low cost and high effi ciency.ZnO is often used in commercial Cu-based catalysts as both a structural and an electronic promoter to stabilize metal Cu nanoparticles and modify metal–support interfaces.Still,the further addition of chemical promoters is essential to further enhance the MSR reaction performance of the Cu/ZnO catalyst.In this work,CeO_(2)-doped Cu/ZnO catalysts were prepared using the coprecipitation method,and the eff ects of CeO_(2)on Cu-based catalysts were systematically investigated.Doping with appropriate CeO_(2)amounts could stabilize small Cu nanoparticles through a strong interaction between CeO_(2)and Cu,leading to the formation of more Cu+–ZnO x interfacial sites.However,higher CeO_(2)contents resulted in the formation of larger Cu nanoparticles and an excess of Cu+–CeO x interfacial sites.Consequently,the Cu/5CeO_(2)/ZnO catalyst with maximal Cu–ZnO interfaces exhibited the highest H 2 production rate of 94.6 mmolH2/(gcat·h),which was 1.5 and 10.2 times higher than those of Cu/ZnO and Cu/CeO_(2),respectively.展开更多
A simple strategy of Cu modification was proposed to broaden the operation temperature window for NbCe catalyst.The best catalyst Cu0.010/Nb1Ce3 presented over 90%NO conversion in a wide temperature range of 200-400℃...A simple strategy of Cu modification was proposed to broaden the operation temperature window for NbCe catalyst.The best catalyst Cu0.010/Nb1Ce3 presented over 90%NO conversion in a wide temperature range of 200-400℃and exhibited an excellent H_(2)O or/and SO_(2) resistance at 275℃.To understand the promotional mechanism of Cu modification,the correlation among the"activity-structure-property"were tried to establish systematically.Cu species highly dispersed on NbCe catalyst to serve as the active component.The strong interaction among Cu,Nb and Ce promoted the emergence of NbO4 and induced more Bronsted acid sites.And Cu modification obviously enhanced the redox behavior of the NbCe catalyst.Besides,EPR probed the Cu species exited in the form of monomeric and dimeric Cu^(2+),the isolated Cu^(2+)acted as catalytic active sites to promote the reaction:Cu^(2+)-NO_(3)^(-)+NO(g)→Cu^(2+)-NO_(2)^(-)+NO_(2)(g).Then the generated NO_(2) would accelerate the fast-SCR reaction process and thus facilitated the lowtemperature deNO_(x) efficiency.Moreover,surface nitrates became unstable and easy to decompose after Cu modification,thus providing additional adsorption and activation sites for NH3,and ensuring the improvement of catalytic activity at high temperature.Since the NH3-SCR reaction followed by E-R reaction pathway efficaciously over Cu_(0.010)/Nb_(1)Ce_(3) catalyst,the excellent H_(2)O and SO_(2) resistance was as expected.展开更多
基金the Key Research and Development Program of China(No.2022YFB2404102)the National Natural Science Foundation of China(Nos.51971093,52171158,52101196)+5 种基金the Key Research and Development Program of Shandong Province,China(Nos.2020ZLYS11,2021ZLGX01,2022CXGC020308,2023CXGC010308)the Major Innovation Projects of Shandong Province,China(Nos.2020CXGC010701,2020CXGC010702)the Young Taishan Scholars,China(No.tsqn202211184)the Shandong Provincial Natural Science Foundation,China(No.ZR2022ME137)the Yantai Science and Technology Planning Project,China(No.2021ZDCX001)the Open Project Program of Shandong Marine Aerospace Equipment Technological Innovation Center(Ludong University),China(No.MAETIC2021-11).
文摘The damage characteristics of different speed sections of Cu−Cr−Zr alloy rail after simulated launch were studied.The microstructure,morphologies and properties of samples were investigated by using XRD,XPS,EBSD,SEM,hardness test,electrochemical test and DSC techniques.It was found that deposition layers were formed on the surfaces of the simulated launch samples.The thickness and surface roughness of these deposition layers increased with increasing the heat effect,suggesting a launch speed dependent damage degree of the arc ablation.The hardness variation of samples is attributed to the effects of the deposition layer and deformation hardening.The surface deposition layer affects corrosion resistance and crystalline characteristics,leading to changes in subsequent service performances.Additionally,the surface texture and plastic deformation ability of the samples are related to the recrystallization degree and deformation grain amount.
文摘Developing Cu single-atom catalysts(SACs)with well-defined active sites is highly desirable for producing CH4 in the electrochemical CO_(2) reduction reaction and understanding the structure-property relationship.Herein,a new graphdiyne analogue with uniformly distributed N_(2)-bidentate(note that N_(2)-bidentate site=N^N-bidentate site;N_(2)≠dinitrogen gas in this work)sites are synthesized.Due to the strong interaction between Cu and the N_(2)-bidentate site,a Cu SAC with isolated undercoordinated Cu-N_(2) sites(Cu1.0/N_(2)-GDY)is obtained,with the Cu loading of 1.0 wt%.Cu1.0/N_(2)-GDY exhibits the highest Faradaic efficiency(FE)of 80.6% for CH_(4) in electrocatalytic reduction of CO_(2) at-0.96 V vs.RHE,and the partial current density of CH_(4) is 160 mA cm^(-2).The selectivity for CH_(4) is maintained above 70% when the total current density is 100 to 300 mA cm^(-2).More remarkably,the Cu1.0/N_(2)-GDY achieves a mass activity of 53.2 A/mgCu toward CH4 under-1.18 V vs.RHE.In situ electrochemical spectroscopic studies reveal that undercoordinated Cu-N_(2) sites are more favorable in generating key ^(*)COOH and ^(*)CHO intermediate than Cu nanoparticle counterparts.This work provides an effective pathway to produce SACs with undercoordinated Metal-N_(2) sites toward efficient electrocatalysis.
文摘MoS_(2)/CuS composite catalysts were successfully synthesized using a one-step hydrothermal method with sodium molybdate dihydrate,thiourea,oxalic acid,and copper nitrate trihydrate as raw materials.The hydrogen pro-duction performance of MoS_(2)/CuS prepared with different molar ratios of Mo to Cu precursors(n_(Mo)∶n_(Cu))as cathodic catalysts was investigated in the two-chamber microbial electrolytic cell(MEC).X-ray diffraction(XRD),X-ray pho-toelectron spectroscopy(XPS),scanning electron microscopy(SEM),transmission electron microscope(TEM),linear scanning voltammetry(LSV),electrochemical impedance analysis(EIS),and cyclic voltammetry(CV)were used to characterize the synthesized catalysts for testing and analyzing the hydrogen-producing performance.The results showed that the hydrogen evolution performance of MoS_(2)/CuS-20%(nMo∶nCu=5∶1)was better than that of platinum(Pt)mesh,and the hydrogen production rate of MoS_(2)/CuS-20%as a cathode in MEC was(0.2031±0.0237)m^(3)_(H_(2))·m^(-3)·d^(-1) for 72 h at an applied voltage of 0.8 V,which was slightly higher than that of Pt mesh of(0.1886±0.0134)m^(3)_(H_(2))·m^(-3)·d^(-1).The addition of a certain amount of CuS not only regulates the electron transfer ability of MoS_(2) but also increases the density of active sites.
基金supports from National Natural Science Foundation of China(Nos.22178059 and 91934301)Natural Science Foundation of Fujian Province,China(2020J01513)+1 种基金Sinochem Quanzhou Energy Technology Co.,Ltd.(ZHQZKJ-19-F-ZS-0076)Qingyuan Innovation Laboratory(No.00121002),and Fujian Hundred Talent Program.
文摘The nature and distribution of Cu species in Cu-SSZ-13 play a vital role in selective catalytic reduction of NO by NH3(NH3-SCR),but existing methods for adjusting the Cu distribution are complex and difficult to control.Herein,we report a simple and effective ion-exchange approach to regulate the Cu distribution in the one-pot synthesized Cu-SSZ-13 that possesses sufficient initial Cu species and thus provides a“natural environment”for adjusting Cu distribution precisely.By using this proposed strategy,a series of Cu-SSZ-13x zeolites with different Cu contents and distributions were obtained.It is shown that the dealumination of the as-synthesized Cu-SSZ-13 during the ion-exchange generates abundant vacant sites in the double six-membered-rings of the SSZ-13 zeolite for relocating Cu2+species and thus allows the redistribution of the Cu species.The catalytic results showed that the ion-exchanged Cu-SSZ-13 zeolites exhibit quite different catalytic performance in NH3-SCR reaction but superior to the parent counterpart.The structure–activity relationship analysis indicates that the redistribution of Cu species rather than other factors(e.g.,crystallinity,chemical composition,and porous structure)is responsible for the improved NH3-SCR performance and SO_(2) and H_(2)O resistance.Our work offers an effective method to precisely adjust the Cu distribution in preparing the industrial SCR catalysts.
基金This work was supported by the National Key R&D Program of China(2022YFB3805504),National Natural Science Foundation of China(22078089)China Postdoctoral Science Foundation(2023M731081)+3 种基金Shanghai Pilot Program for Basic Research(22TQ1400100-7)the Basic Research Program of Science and Technology Commission of Shanghai Municipality(22JC1400600)Open Foundation of Shanghai Jiao Tong University Shaoxing Research Institute of Renewable Energy and Molecular Engineering(Grant No.JDSX2022046)Shanghai Super Postdoctoral Fellow.
文摘Cu-based catalysts have been extensively used in methanol steam reforming(MSR)reactions because of their low cost and high effi ciency.ZnO is often used in commercial Cu-based catalysts as both a structural and an electronic promoter to stabilize metal Cu nanoparticles and modify metal–support interfaces.Still,the further addition of chemical promoters is essential to further enhance the MSR reaction performance of the Cu/ZnO catalyst.In this work,CeO_(2)-doped Cu/ZnO catalysts were prepared using the coprecipitation method,and the eff ects of CeO_(2)on Cu-based catalysts were systematically investigated.Doping with appropriate CeO_(2)amounts could stabilize small Cu nanoparticles through a strong interaction between CeO_(2)and Cu,leading to the formation of more Cu+–ZnO x interfacial sites.However,higher CeO_(2)contents resulted in the formation of larger Cu nanoparticles and an excess of Cu+–CeO x interfacial sites.Consequently,the Cu/5CeO_(2)/ZnO catalyst with maximal Cu–ZnO interfaces exhibited the highest H 2 production rate of 94.6 mmolH2/(gcat·h),which was 1.5 and 10.2 times higher than those of Cu/ZnO and Cu/CeO_(2),respectively.
基金Financial support from the National Natural Science Foundation of China,China(Nos.21972062,21976081,21976111)。
文摘A simple strategy of Cu modification was proposed to broaden the operation temperature window for NbCe catalyst.The best catalyst Cu0.010/Nb1Ce3 presented over 90%NO conversion in a wide temperature range of 200-400℃and exhibited an excellent H_(2)O or/and SO_(2) resistance at 275℃.To understand the promotional mechanism of Cu modification,the correlation among the"activity-structure-property"were tried to establish systematically.Cu species highly dispersed on NbCe catalyst to serve as the active component.The strong interaction among Cu,Nb and Ce promoted the emergence of NbO4 and induced more Bronsted acid sites.And Cu modification obviously enhanced the redox behavior of the NbCe catalyst.Besides,EPR probed the Cu species exited in the form of monomeric and dimeric Cu^(2+),the isolated Cu^(2+)acted as catalytic active sites to promote the reaction:Cu^(2+)-NO_(3)^(-)+NO(g)→Cu^(2+)-NO_(2)^(-)+NO_(2)(g).Then the generated NO_(2) would accelerate the fast-SCR reaction process and thus facilitated the lowtemperature deNO_(x) efficiency.Moreover,surface nitrates became unstable and easy to decompose after Cu modification,thus providing additional adsorption and activation sites for NH3,and ensuring the improvement of catalytic activity at high temperature.Since the NH3-SCR reaction followed by E-R reaction pathway efficaciously over Cu_(0.010)/Nb_(1)Ce_(3) catalyst,the excellent H_(2)O and SO_(2) resistance was as expected.
