采用扫描电镜、能谱仪、微区X射线衍射仪研究了Cu Ni Sn Ti活性钎料钎焊立方氮化硼（c-BN）界面产物的微观结构和形成机理,并运用动力学分析了界面反应产物的生长过程及反应激活能.结果表明,钎焊过程中CuNi Sn Ti钎料对c-BN具有良好的...采用扫描电镜、能谱仪、微区X射线衍射仪研究了Cu Ni Sn Ti活性钎料钎焊立方氮化硼（c-BN）界面产物的微观结构和形成机理,并运用动力学分析了界面反应产物的生长过程及反应激活能.结果表明,钎焊过程中CuNi Sn Ti钎料对c-BN具有良好的润湿性,钎料与c-BN发生化学反应,实现c-BN与钢基体的可靠连接;钎料与c-BN界面处生成Ti-N和Ti-B化合物新相,形成了钎料/Ti N/Ti B/Ti B2/c-BN的结构形式;在钎焊温度1 323∽1 398 K,保温时间5∽20 min之间依据抛物线生长法则指出界面处产生的化学反应和原子间的相互扩散是促使界面反应层形成与生长的主要因素及形成机理.展开更多
Electrochemical CO2 reduction is a promising strategy for the utilization of CO2 and intermittent excess electricity.Cu is the only single metal catalyst that can electrochemically convert CO2 into multicarbon product...Electrochemical CO2 reduction is a promising strategy for the utilization of CO2 and intermittent excess electricity.Cu is the only single metal catalyst that can electrochemically convert CO2 into multicarbon products.However,Cu exhibits an unfavorable activity and selectivity for the generation of C2 products because of the insufficient amount of CO*provided for the C‐C coupling.Based on the strong CO2 adsorption and ultrafast reaction kinetics of CO*formation on Pd,an intimate CuPd(100)interface was designed to lower the intermediate reaction barriers and improve the efficiency of C2 product formation.Density functional theory(DFT)calculations showed that the CuPd(100)interface enhanced the CO2 adsorption and decreased the CO2*hydrogenation energy barrier,which was beneficial for the C‐C coupling.The potential‐determining step(PDS)barrier of CO2 to C2 products on the CuPd(100)interface was 0.61 eV,which was lower than that on Cu(100)(0.72 eV).Encouraged by the DFT calculation results,the CuPd(100)interface catalyst was prepared by a facile chemical solution method and characterized by transmission electron microscopy.CO2 temperature‐programmed desorption and gas sensor experiments further confirmed the enhancement of the CO2 adsorption and CO2*hydrogenation ability of the CuPd(100)interface catalyst.Specifically,the obtained CuPd(100)interface catalyst exhibited a C2 Faradaic efficiency of 50.3%±1.2%at‒1.4 VRHE in 0.1 M KHCO3,which was 2.1 times higher than that of the Cu catalyst(23.6%±1.5%).This study provides the basis for the rational design of Cu‐based electrocatalysts for the generation of multicarbon products by fine‐tuning the intermediate reaction barriers.展开更多
文摘采用扫描电镜、能谱仪、微区X射线衍射仪研究了Cu Ni Sn Ti活性钎料钎焊立方氮化硼（c-BN）界面产物的微观结构和形成机理,并运用动力学分析了界面反应产物的生长过程及反应激活能.结果表明,钎焊过程中CuNi Sn Ti钎料对c-BN具有良好的润湿性,钎料与c-BN发生化学反应,实现c-BN与钢基体的可靠连接;钎料与c-BN界面处生成Ti-N和Ti-B化合物新相,形成了钎料/Ti N/Ti B/Ti B2/c-BN的结构形式;在钎焊温度1 323∽1 398 K,保温时间5∽20 min之间依据抛物线生长法则指出界面处产生的化学反应和原子间的相互扩散是促使界面反应层形成与生长的主要因素及形成机理.
基金Projec(t50371069)Supported by the National Natural Science Foundation of ChinaProjec(t20030699013)Supported by the State Educational Ministry Doctoral FoundationProject(04G53044) Supported by Foundation of Aviation Science
文摘Electrochemical CO2 reduction is a promising strategy for the utilization of CO2 and intermittent excess electricity.Cu is the only single metal catalyst that can electrochemically convert CO2 into multicarbon products.However,Cu exhibits an unfavorable activity and selectivity for the generation of C2 products because of the insufficient amount of CO*provided for the C‐C coupling.Based on the strong CO2 adsorption and ultrafast reaction kinetics of CO*formation on Pd,an intimate CuPd(100)interface was designed to lower the intermediate reaction barriers and improve the efficiency of C2 product formation.Density functional theory(DFT)calculations showed that the CuPd(100)interface enhanced the CO2 adsorption and decreased the CO2*hydrogenation energy barrier,which was beneficial for the C‐C coupling.The potential‐determining step(PDS)barrier of CO2 to C2 products on the CuPd(100)interface was 0.61 eV,which was lower than that on Cu(100)(0.72 eV).Encouraged by the DFT calculation results,the CuPd(100)interface catalyst was prepared by a facile chemical solution method and characterized by transmission electron microscopy.CO2 temperature‐programmed desorption and gas sensor experiments further confirmed the enhancement of the CO2 adsorption and CO2*hydrogenation ability of the CuPd(100)interface catalyst.Specifically,the obtained CuPd(100)interface catalyst exhibited a C2 Faradaic efficiency of 50.3%±1.2%at‒1.4 VRHE in 0.1 M KHCO3,which was 2.1 times higher than that of the Cu catalyst(23.6%±1.5%).This study provides the basis for the rational design of Cu‐based electrocatalysts for the generation of multicarbon products by fine‐tuning the intermediate reaction barriers.
