以煅烧三聚氰胺后形成的C3N4材料为氮源,柠檬酸为碳源,六水合三氯化铁为铁源,通过两步法合成FeN/C催化剂,并考察该催化剂对氧还原反应的电催化能力。采用XRD、SEM、Raman、XPS等表征手段对Fe-N/C催化剂的晶体结构和元素化学状态进行综...以煅烧三聚氰胺后形成的C3N4材料为氮源,柠檬酸为碳源,六水合三氯化铁为铁源,通过两步法合成FeN/C催化剂,并考察该催化剂对氧还原反应的电催化能力。采用XRD、SEM、Raman、XPS等表征手段对Fe-N/C催化剂的晶体结构和元素化学状态进行综合评价;以CV和LSV等电化学测试手段探究Fe-N/C催化剂的氧还原电催化能力。研究结果表明,Fe-N/C催化剂具有管状形貌、较高的石墨氮含量和较佳的氧还原电催化能力。通过对电化学性能关键参数进行分析发现,Fe-N/C催化剂的起始电位是1.071 V vs. RHE,半波电位是0.911 V vs. RHE,极限电流密度是5.943 mA/cm2。展开更多
Fe-N/C is a promising oxygen reduction reaction(ORR)catalyst to substitute the current widely used precious metal platinum.Cost-effectively fabricating the Fe-N/C material with high catalytic activity and getting in-d...Fe-N/C is a promising oxygen reduction reaction(ORR)catalyst to substitute the current widely used precious metal platinum.Cost-effectively fabricating the Fe-N/C material with high catalytic activity and getting in-depth insight into the responsible catalytic site are of great significance.In this work,we proposed to use biomass,tea leaves waste,as the precursor to prepare ORR catalyst.By adding 5%FeCl3(wt%)into tea precursor,the pyrolysis product(i.e.,5%Fe-N/C)exhibited an excellent four-electron ORR activity,whose onset potential was only 10 m V lower than that of commercial Pt/C.The limiting current density of 5%Fe-N/C(5.75 m A/cm^(2))was even higher than Pt/C(5.44 m A/cm^(2)).Compared with other biomass or metal organic frameworks derived catalysts,5%Fe-N/C showed similar ORR activity.Also,both the methanol tolerance and material stability performances of as-prepared 5%Fe-N/C catalyst were superior to that of Pt/C.X-ray adsorption fine structure characterization revealed that the FeN4O2might be the possible catalytic site.An appropriate amount of iron chloride addition not only facilitated catalytic site formation,but also enhanced material conductivity and reaction kinetics.The results of this work may be useful for the Fe based transition metal ORR catalyst design and application.展开更多
[目的]为进一步拓展单原子催化剂在亚硝酸盐还原制氨领域的应用,提出了一种铁-氮-碳(Fe-N-C)单原子催化剂电催化亚硝酸盐还原制氨的新体系.[方法]以二氧化硅为硬模板,2,6-二氨基吡啶为碳氮前驱体,硝酸铁为金属盐,通过“热解-刻蚀”策略...[目的]为进一步拓展单原子催化剂在亚硝酸盐还原制氨领域的应用,提出了一种铁-氮-碳(Fe-N-C)单原子催化剂电催化亚硝酸盐还原制氨的新体系.[方法]以二氧化硅为硬模板,2,6-二氨基吡啶为碳氮前驱体,硝酸铁为金属盐,通过“热解-刻蚀”策略制备了Fe-N-C单原子催化剂,并将其应用于亚硝酸盐制氨反应.[结果]多种结构表征结果显示,Fe-N-C催化剂表面的Fe物种呈现高度分散特征并以单原子形式存在.此外,Fe物种的化学环境主要是+2和+3价混合态,且通过与4个吡啶氮配位而稳定存在,即Fe-N-C催化剂的金属中心微观配位环境为Fe-N4结构.与纯氮碳(N-C)载体相比,本研究制备的Fe-N-C催化剂具有优异的亚硝酸盐还原性能,不仅表现出更高的起始还原电位(0 V vs可逆氢电极),具有接近100%的产氨法拉第效率和高的氨产率[8.4 mg/(h·cm^(2))],并且在连续20次催化循环测试中显示出优异的催化稳定性.[结论]本研究制备的Fe-N-C单原子催化剂对亚硝酸盐还原制氨具有优异的电催化活性,其高活性可能来源于对NO_(2)^(-)的显著吸附,并进一步促进活性氢参与脱氧加氢过程.该Fe-N-C单原子催化亚硝酸盐还原体系可为后续合成氨的活性中心设计提供指导方向.展开更多
以苯胺为原料,二氧化硅球为硬模板,采用原位聚合法制备出具有多孔结构的氮掺杂碳球,然后以三氯化铁为铁源,利用沉淀法制备出球状多孔Fe-N-C复合催化剂.通过SEM、TEM、EDS等分析手段对Fe-N-C的形貌结构及组成进行了表征,使用旋转圆盘电...以苯胺为原料,二氧化硅球为硬模板,采用原位聚合法制备出具有多孔结构的氮掺杂碳球,然后以三氯化铁为铁源,利用沉淀法制备出球状多孔Fe-N-C复合催化剂.通过SEM、TEM、EDS等分析手段对Fe-N-C的形貌结构及组成进行了表征,使用旋转圆盘电极测试了其在碱性条件下对氧还原反应的催化活性.结果表明,其起始电位(0.961 V vs RHE)与半波电位(0.835 V vs RHE)与商业化Pt/C相近,经过7 000 s后,Fe-N-C仍保持93.53%的相对电流,显示出优异的氧还原催化稳定性.展开更多
The great interest of Fe-N/C based Zn-air batteries and fuel cells intrigues large numbers of studies on modulating the pore structure for fast mass transport and the electronic structure of atomic Fe centers for enha...The great interest of Fe-N/C based Zn-air batteries and fuel cells intrigues large numbers of studies on modulating the pore structure for fast mass transport and the electronic structure of atomic Fe centers for enhancing intrinsic activity for oxygen reduction reaction(ORR).A Zn-assisted strategy herein is developed to synthesize a honeycomb-like micro-nanoscale porous Fe-N/C catalyst with atomic FeN_(3)Cl active sites.Specifically,Zn-guided synthesis of honeycomb-like porous carbon supported ZnO,ZnO-templated assembly of hemin modified ZIF-8 on honeycomb-like carbon and Zn/ZnO-assisted pyrolysis of the ZIF-8 precursor are involved.The synthetic mechanism is revealed by in-situ transmission electron microscopy imaging and in-situ X-ray diffraction analysis.Density functional theory calculations demonstrate FeN_(3)Cl can prominently lower the ORR energy barrier on the Fe centers,greatly facilitating catalytic kinetics.Hence,high ORR performance,including half-wave potentials of 0.81 V in acidic conditions and 0.91 V under alkaline media,is achieved.Besides,Zn-air batteries and H_(2)-O_(2)fuel cells base on the resulting catalyst are investigated,also exhibiting excellent battery/cell performances.This study provides a novel strategy for the preparation of honeycomb-like micro-nanoscale porous single-atom catalysts as well as a significant new insight on the catalytic mechanisms,helping to advance in energy devices.展开更多
Proton exchange membrane fuel cells(PEMFC)have attracted much attention because of their high energy conversion efficiency,high power density and zero emission of pollutants.However,the high cost of the cathode platin...Proton exchange membrane fuel cells(PEMFC)have attracted much attention because of their high energy conversion efficiency,high power density and zero emission of pollutants.However,the high cost of the cathode platinum group metal(PGM)catalysts creates a barrier for the large-scale application of PEMFC.Tremendous efforts have been devoted to the development of low-cost PGM-free catalysts,especially the Fe-N-C catalysts,to replace the expensive PGM catalysts.However,the characterization methods and evaluation standards of the catalysts varies,which is not conducive to the comparison of PGM-free catalysts.U.S.Department of energy(DOE)is the only authority that specifies the testing standards and activity targets for PGM-free catalysts.In this review,the major breakthroughs of Fe-N-C catalysts are outlined with the reference of DOE standards and targets.The preparation and characteristics of these highly active Fe-N-C catalysts are briefly introduced.Moreover,the efforts on improving the mass transfer and the durability issue of Fe-N-C fuel cell are discussed.Finally,the prospective directions concerning the comprehensive evaluation of the Fe-N-C catalysts are proposed.展开更多
文摘以煅烧三聚氰胺后形成的C3N4材料为氮源,柠檬酸为碳源,六水合三氯化铁为铁源,通过两步法合成FeN/C催化剂,并考察该催化剂对氧还原反应的电催化能力。采用XRD、SEM、Raman、XPS等表征手段对Fe-N/C催化剂的晶体结构和元素化学状态进行综合评价;以CV和LSV等电化学测试手段探究Fe-N/C催化剂的氧还原电催化能力。研究结果表明,Fe-N/C催化剂具有管状形貌、较高的石墨氮含量和较佳的氧还原电催化能力。通过对电化学性能关键参数进行分析发现,Fe-N/C催化剂的起始电位是1.071 V vs. RHE,半波电位是0.911 V vs. RHE,极限电流密度是5.943 mA/cm2。
基金the National Natural Science Foundation of China(No.51908172)for the support of this study。
文摘Fe-N/C is a promising oxygen reduction reaction(ORR)catalyst to substitute the current widely used precious metal platinum.Cost-effectively fabricating the Fe-N/C material with high catalytic activity and getting in-depth insight into the responsible catalytic site are of great significance.In this work,we proposed to use biomass,tea leaves waste,as the precursor to prepare ORR catalyst.By adding 5%FeCl3(wt%)into tea precursor,the pyrolysis product(i.e.,5%Fe-N/C)exhibited an excellent four-electron ORR activity,whose onset potential was only 10 m V lower than that of commercial Pt/C.The limiting current density of 5%Fe-N/C(5.75 m A/cm^(2))was even higher than Pt/C(5.44 m A/cm^(2)).Compared with other biomass or metal organic frameworks derived catalysts,5%Fe-N/C showed similar ORR activity.Also,both the methanol tolerance and material stability performances of as-prepared 5%Fe-N/C catalyst were superior to that of Pt/C.X-ray adsorption fine structure characterization revealed that the FeN4O2might be the possible catalytic site.An appropriate amount of iron chloride addition not only facilitated catalytic site formation,but also enhanced material conductivity and reaction kinetics.The results of this work may be useful for the Fe based transition metal ORR catalyst design and application.
文摘[目的]为进一步拓展单原子催化剂在亚硝酸盐还原制氨领域的应用,提出了一种铁-氮-碳(Fe-N-C)单原子催化剂电催化亚硝酸盐还原制氨的新体系.[方法]以二氧化硅为硬模板,2,6-二氨基吡啶为碳氮前驱体,硝酸铁为金属盐,通过“热解-刻蚀”策略制备了Fe-N-C单原子催化剂,并将其应用于亚硝酸盐制氨反应.[结果]多种结构表征结果显示,Fe-N-C催化剂表面的Fe物种呈现高度分散特征并以单原子形式存在.此外,Fe物种的化学环境主要是+2和+3价混合态,且通过与4个吡啶氮配位而稳定存在,即Fe-N-C催化剂的金属中心微观配位环境为Fe-N4结构.与纯氮碳(N-C)载体相比,本研究制备的Fe-N-C催化剂具有优异的亚硝酸盐还原性能,不仅表现出更高的起始还原电位(0 V vs可逆氢电极),具有接近100%的产氨法拉第效率和高的氨产率[8.4 mg/(h·cm^(2))],并且在连续20次催化循环测试中显示出优异的催化稳定性.[结论]本研究制备的Fe-N-C单原子催化剂对亚硝酸盐还原制氨具有优异的电催化活性,其高活性可能来源于对NO_(2)^(-)的显著吸附,并进一步促进活性氢参与脱氧加氢过程.该Fe-N-C单原子催化亚硝酸盐还原体系可为后续合成氨的活性中心设计提供指导方向.
文摘Fe-N-C材料是目前非常有潜力的一类非贵金属氧还原电极催化剂。本论文分别以导电碳黑(HG-1F)、苯胺、Fe Cl3为碳载体、含氮前驱体、铁前驱体,依次经过聚合、热处理和酸处理获得了多孔Fe-N-C材料。电化学测试结果表明,多孔Fe-N-C材料在0.1 M KOH中催化氧还原反应(ORR)的活性随酸处理时间呈火山型变化,其中酸处理4 h的样品对ORR具有较高的催化活性,促使ORR主要以4电子反应途径进行。
文摘以苯胺为原料,二氧化硅球为硬模板,采用原位聚合法制备出具有多孔结构的氮掺杂碳球,然后以三氯化铁为铁源,利用沉淀法制备出球状多孔Fe-N-C复合催化剂.通过SEM、TEM、EDS等分析手段对Fe-N-C的形貌结构及组成进行了表征,使用旋转圆盘电极测试了其在碱性条件下对氧还原反应的催化活性.结果表明,其起始电位(0.961 V vs RHE)与半波电位(0.835 V vs RHE)与商业化Pt/C相近,经过7 000 s后,Fe-N-C仍保持93.53%的相对电流,显示出优异的氧还原催化稳定性.
基金supported by the National Natural Science Foundation of China(52372049)Yunnan Fundamental Research Projects(202301AW070016)+2 种基金China Postdoctoral Science Foundation(Certificate Number:2023M743573)Postdoctoral Fellowship Program of CPSF(GZC20232744)Project of Xingdian Talent Support Plan.
文摘The great interest of Fe-N/C based Zn-air batteries and fuel cells intrigues large numbers of studies on modulating the pore structure for fast mass transport and the electronic structure of atomic Fe centers for enhancing intrinsic activity for oxygen reduction reaction(ORR).A Zn-assisted strategy herein is developed to synthesize a honeycomb-like micro-nanoscale porous Fe-N/C catalyst with atomic FeN_(3)Cl active sites.Specifically,Zn-guided synthesis of honeycomb-like porous carbon supported ZnO,ZnO-templated assembly of hemin modified ZIF-8 on honeycomb-like carbon and Zn/ZnO-assisted pyrolysis of the ZIF-8 precursor are involved.The synthetic mechanism is revealed by in-situ transmission electron microscopy imaging and in-situ X-ray diffraction analysis.Density functional theory calculations demonstrate FeN_(3)Cl can prominently lower the ORR energy barrier on the Fe centers,greatly facilitating catalytic kinetics.Hence,high ORR performance,including half-wave potentials of 0.81 V in acidic conditions and 0.91 V under alkaline media,is achieved.Besides,Zn-air batteries and H_(2)-O_(2)fuel cells base on the resulting catalyst are investigated,also exhibiting excellent battery/cell performances.This study provides a novel strategy for the preparation of honeycomb-like micro-nanoscale porous single-atom catalysts as well as a significant new insight on the catalytic mechanisms,helping to advance in energy devices.
基金supported by the National Thousand Talents Plan of Chinathe National Natural Science Foundation of China(Grant Nos.21673014 and U1766216)+1 种基金the 111 project(B17002)funded by the Ministry of Education of Chinathe Fundamental Research Funds for the Central Universities of China
文摘Proton exchange membrane fuel cells(PEMFC)have attracted much attention because of their high energy conversion efficiency,high power density and zero emission of pollutants.However,the high cost of the cathode platinum group metal(PGM)catalysts creates a barrier for the large-scale application of PEMFC.Tremendous efforts have been devoted to the development of low-cost PGM-free catalysts,especially the Fe-N-C catalysts,to replace the expensive PGM catalysts.However,the characterization methods and evaluation standards of the catalysts varies,which is not conducive to the comparison of PGM-free catalysts.U.S.Department of energy(DOE)is the only authority that specifies the testing standards and activity targets for PGM-free catalysts.In this review,the major breakthroughs of Fe-N-C catalysts are outlined with the reference of DOE standards and targets.The preparation and characteristics of these highly active Fe-N-C catalysts are briefly introduced.Moreover,the efforts on improving the mass transfer and the durability issue of Fe-N-C fuel cell are discussed.Finally,the prospective directions concerning the comprehensive evaluation of the Fe-N-C catalysts are proposed.
