Photoelectrochemical CO_(2)reduction to multi-carbon products fuels remains challenged by inefficient C–C coupling and competing proton reduction reaction.Herein,we designed a cationic covalent organic framework(COF+...Photoelectrochemical CO_(2)reduction to multi-carbon products fuels remains challenged by inefficient C–C coupling and competing proton reduction reaction.Herein,we designed a cationic covalent organic framework(COF+)to create an electrostatic microenvironment that synergizes with CuPt alloy nanoparticles for selective ethylene/ethane production.By spatially decoupling CO_(2)enrichment from proton exclusion,the COF^(+)/CuPt interface simultaneously facilitates CO_(2)accessibility while impeding H+migration,suppressing the hydrogen evolution reaction(HER).This unique microenvironment stabilizes key anionic intermediates(*COO^(−),*OCCO^(−))and promotes*CO dimerization,steering electron transfer toward C–C coupling.The optimized system achieves a record-high Faradaic efficiency of 51.5%±5.3%for ethane and 10.6%±2.5%for ethylene with a total C2+yield exceeding 62%at−0.25 V vs.RHE and high stability(>300 min),representing the highest performance for photoelectrochemical CO_(2)reduction to ethane.The combined analyses of in situ spectroscopy and theoretical calculations reveal that electrostatic field effects lower the energy barrier for*OCCO formation while accelerating hydrogenation kinetics.Therefore,this work demonstrates that microenvironment modification of the active site by cationic covalent organic framework is a versatile strategy for solar-driven CO_(2)conversion into value-added hydrocarbons.展开更多
Molecular dynamics simulations were carried out to study the effect of chemical short-range order(CSRO)on the primary radiation damage in TiVTaNb high-entropy alloys(HEAs).We have performed displacement cascade simula...Molecular dynamics simulations were carried out to study the effect of chemical short-range order(CSRO)on the primary radiation damage in TiVTaNb high-entropy alloys(HEAs).We have performed displacement cascade simulations to explore the CSRO effect on the generation and evolution behaviors of irradiation defects.The results demonstrate that CSRO can suppress the formation of Frenkel pairs in TiVTaNb HEAs,with the suppression effect becoming more pronounced as the degree of CSRO increases.CSRO can change the types of interstitial defects generated during cascade collisions.Specifically,as the degree of CSRO increases,the proportion of Ti-related interstitials shows a marked enhancement,primarily evidenced by a significant rise in Ti–Ti dumbbells accompanied by a corresponding decrease in Ti–V dumbbells.CSRO exhibits negligible influence on defect clustering and the nucleation and evolution of dislocation loops.Regardless of CSRO conditions,TiVTaNb HEAs preserve exceptional radiation tolerance throughout the cascade damage process,suggesting that the intrinsic properties of this multi-principal element system dominate its radiation response.These findings provide fundamental insights into the CSRO effect on defect formation and evolution behaviors in HEAs,which may provide new design strategies for high-entropy alloys.展开更多
The Ba,Y and A1 co-doped Li_(7)La_(3)Zr_(2)O_(12)(LLZO)was prepared by the solid-state reaction method.Effect of sintering on the crystallographic structure,morphology,total conductivity,relative density and contracti...The Ba,Y and A1 co-doped Li_(7)La_(3)Zr_(2)O_(12)(LLZO)was prepared by the solid-state reaction method.Effect of sintering on the crystallographic structure,morphology,total conductivity,relative density and contractibility rate of the prepared solid electrolyte was studied,respectively.The sintered samples were characterized by X-ray diffractometer(XRD),scanning electron microscopy(SEM),electrochemical impedance spectra(EIS)and inductively coupled plasma atomic emission spectrometry(ICP-AES)techniques,respectively.The cubic garnet phase Ba,Y and Al co-doped LLZO is obtained,and the room-temperature total conductivity of the Ba,Y and Al co-doped LLZO solid electrolyte is improved significantly by eliminating the grain boundary resistances and improving the densifications with controlling sintering temperature(T)and time(t),respectively.Sintering at 1160-1190℃for 12 h and at 1190℃for6-15 h,respectively,the Ba,Y and Al co-doped LLZO solid electrolytes are cubic garnet phase.Sintering at1180-1190℃for 12 h and at 1190℃for 12-18 h,respectively,SEM images of the cross section of the Ba,Y and Al co-doped LLZO solid electrolytes exhibit the distinctively flattened morphology without any noticeable grain boundaries.The total conductivity,relative density and contractibility rate of Li_(6.52)La_(2.98)-Ba_(0.02)Zr_(1.9)Y_(0.1)Al_(0.2)O_(12)solid electrolyte are 2.96×10^(-4) S·cm^(-1),94.19%and 18.61%,respectively.展开更多
基金financial support from the National Natural Science Foundation of China(No.52273187)the Guangdong Basic and Applied Basic Research Foundation(2022A1515110372,2023A1515011306,2023A1515240077)+1 种基金the National Key Research and Development Program of China(2022YFA1502900)the Guangdong-Hong Kong Joint Laboratory for Preparation and Application of Ordered Structural Materials of Guangdong Province(2023B1212120011).
文摘Photoelectrochemical CO_(2)reduction to multi-carbon products fuels remains challenged by inefficient C–C coupling and competing proton reduction reaction.Herein,we designed a cationic covalent organic framework(COF+)to create an electrostatic microenvironment that synergizes with CuPt alloy nanoparticles for selective ethylene/ethane production.By spatially decoupling CO_(2)enrichment from proton exclusion,the COF^(+)/CuPt interface simultaneously facilitates CO_(2)accessibility while impeding H+migration,suppressing the hydrogen evolution reaction(HER).This unique microenvironment stabilizes key anionic intermediates(*COO^(−),*OCCO^(−))and promotes*CO dimerization,steering electron transfer toward C–C coupling.The optimized system achieves a record-high Faradaic efficiency of 51.5%±5.3%for ethane and 10.6%±2.5%for ethylene with a total C2+yield exceeding 62%at−0.25 V vs.RHE and high stability(>300 min),representing the highest performance for photoelectrochemical CO_(2)reduction to ethane.The combined analyses of in situ spectroscopy and theoretical calculations reveal that electrostatic field effects lower the energy barrier for*OCCO formation while accelerating hydrogenation kinetics.Therefore,this work demonstrates that microenvironment modification of the active site by cationic covalent organic framework is a versatile strategy for solar-driven CO_(2)conversion into value-added hydrocarbons.
基金Project supported by the Youth Program of the National Natural Science Foundation of China(Grant No.12405324)the CNNC Science Fund for Talented Young Scholars(Grant No.24940)the CNNC Basic Science Fund(Grant No.24851)。
文摘Molecular dynamics simulations were carried out to study the effect of chemical short-range order(CSRO)on the primary radiation damage in TiVTaNb high-entropy alloys(HEAs).We have performed displacement cascade simulations to explore the CSRO effect on the generation and evolution behaviors of irradiation defects.The results demonstrate that CSRO can suppress the formation of Frenkel pairs in TiVTaNb HEAs,with the suppression effect becoming more pronounced as the degree of CSRO increases.CSRO can change the types of interstitial defects generated during cascade collisions.Specifically,as the degree of CSRO increases,the proportion of Ti-related interstitials shows a marked enhancement,primarily evidenced by a significant rise in Ti–Ti dumbbells accompanied by a corresponding decrease in Ti–V dumbbells.CSRO exhibits negligible influence on defect clustering and the nucleation and evolution of dislocation loops.Regardless of CSRO conditions,TiVTaNb HEAs preserve exceptional radiation tolerance throughout the cascade damage process,suggesting that the intrinsic properties of this multi-principal element system dominate its radiation response.These findings provide fundamental insights into the CSRO effect on defect formation and evolution behaviors in HEAs,which may provide new design strategies for high-entropy alloys.
基金financially supported by the National Natural Science Foundation of China(Nos.51572176 and 51372153)the Plateau Discipline Construction Program from Shanghai Municipal Education Commission(No.0817)the Collaborative Innovation Fund of Shanghai Institute of Technology(No.XTCX2017-5)。
文摘The Ba,Y and A1 co-doped Li_(7)La_(3)Zr_(2)O_(12)(LLZO)was prepared by the solid-state reaction method.Effect of sintering on the crystallographic structure,morphology,total conductivity,relative density and contractibility rate of the prepared solid electrolyte was studied,respectively.The sintered samples were characterized by X-ray diffractometer(XRD),scanning electron microscopy(SEM),electrochemical impedance spectra(EIS)and inductively coupled plasma atomic emission spectrometry(ICP-AES)techniques,respectively.The cubic garnet phase Ba,Y and Al co-doped LLZO is obtained,and the room-temperature total conductivity of the Ba,Y and Al co-doped LLZO solid electrolyte is improved significantly by eliminating the grain boundary resistances and improving the densifications with controlling sintering temperature(T)and time(t),respectively.Sintering at 1160-1190℃for 12 h and at 1190℃for6-15 h,respectively,the Ba,Y and Al co-doped LLZO solid electrolytes are cubic garnet phase.Sintering at1180-1190℃for 12 h and at 1190℃for 12-18 h,respectively,SEM images of the cross section of the Ba,Y and Al co-doped LLZO solid electrolytes exhibit the distinctively flattened morphology without any noticeable grain boundaries.The total conductivity,relative density and contractibility rate of Li_(6.52)La_(2.98)-Ba_(0.02)Zr_(1.9)Y_(0.1)Al_(0.2)O_(12)solid electrolyte are 2.96×10^(-4) S·cm^(-1),94.19%and 18.61%,respectively.
