Fe/N/C is a promising non-platinum catalyst for the oxygen reduction reaction （ORR）. Even so, mass transfer remains a challenge in the application of Fe/N/C to proton exchange membrane fuel cells, due to the high ca...Fe/N/C is a promising non-platinum catalyst for the oxygen reduction reaction （ORR）. Even so, mass transfer remains a challenge in the application of Fe/N/C to proton exchange membrane fuel cells, due to the high catalyst loadings required. In the present work, mesoporous Fe/N/C was syn- thesized through heat treatment of K]600 carbon black coated with poly-2-aminobenzimidazole and FeC13. The as-prepared Fe/N/C possesses a unique hollow-shell structure that contains a buffer zone allowing both water formation and vaporization, and also facilitates the mass transfer of gas- eous oxygen. This catalyst generated an oxygen reduction reaction activiW of 9.21 A/g in conjunc- tion with a peak power density of 0.71 W/cm2.展开更多
An environmentally friendly precursor, adenosine, has been used as a dual source of C and N to synthesize nitrogen-doped carbon catalyst with/without Fe. A hydrothermal carbonization method has been used and water is ...An environmentally friendly precursor, adenosine, has been used as a dual source of C and N to synthesize nitrogen-doped carbon catalyst with/without Fe. A hydrothermal carbonization method has been used and water is the carbonization media. The morphology of samples with/without Fe component has been compared by HRTEM, and the result shows that Fe can promote the graphitization of carbon. Further electro-chemical test shows that the oxygen reduction reaction（ORR） catalytic activity of Fe-containing sample（C–Fe N） is much higher than that of the Fe-free sample（C–N）. Additionally, the intermediates of C–Fe N formed during each synthetic procedure have been thoroughly characterized by multiple methods,and the function of each procedure has been discussed. The C–Fe N sample exhibits high electro-catalytic stability and superior electro-catalytic activity toward ORR in alkaline media, with its half-wave potential 20 mV lower than that of commercial Pt/C（40 wt%）. It is further incorporated into alkaline polymer electrolyte fuel cell（APEFC） as the cathode material and led to a power density of 100 m W/cm;.展开更多
The state-of-the-art Fe/N/C catalyst has presented comparable initial cathode performance to the benchmark Pt/C catalyst in proton exchange membrane fuel cells(PEMFCs).However,the major bottleneck is its significant a...The state-of-the-art Fe/N/C catalyst has presented comparable initial cathode performance to the benchmark Pt/C catalyst in proton exchange membrane fuel cells(PEMFCs).However,the major bottleneck is its significant activity decay in real-world PEMFC cells.The superposed“fast decay”and“slow decay”have been well documented to describe the degradation process of Fe/N/C catalysts during PEMFC operation.The fast decay has been well understood in close relation to the demetallation at the initial 15-h stability test.Nevertheless,it is still unclear how the remanent active sites evolve after demetallation.To this end,the catalyst performance and evolution of a typical Fe/N/C active site were herein investigated through postmortem characterizations of the membrane electrode assemblies(MEAs)after different operations.It is presented that 1 bar pressure and 80℃ temperature are the optimized conditions for Fe/N/C MEA.Particularly,the“fast decay”in the initial 15 h is immune to the various operating parameters,while the“slow decay”highly depends on the applied temperature and pressure.According to the X-ray absorption spectra(XAS)analysis and stability test of MEA,the gradual evolution of Fe-N coordination to Fe-O is found correlated with the“slow decay”and accounts for the catalyst decay after the demetallation process.展开更多
The oxygen reduction reaction(ORR),an important process in Zn-air batteries(ZABs),shows sluggish reaction kinetics,which significantly impairs the further improvement of battery performance.Thus,rationally designing c...The oxygen reduction reaction(ORR),an important process in Zn-air batteries(ZABs),shows sluggish reaction kinetics,which significantly impairs the further improvement of battery performance.Thus,rationally designing cathodic catalysts for ZABs has drawn sufficient attention.We herein synthesize and characterize Fe/N/F-tridoped CNTs(FeNFCs)by annealing the postsynthesized trifluoroacetic anhydridemodified Fe-MIL-88B-NH_(2)nanocrystals with melamine at high temperature in a N_(2)atmosphere.Benefiting from the Fe/N/F element doping,high specific surface area,and CNT structure,the FeNFC800 catalyst prepared at 800℃exhibits a preferable half-wave potential of 0.829 V vs.RHE.The Zn-air battery equipped with Fe NFC800 shows a high open-circuit voltage of 1.47 V,a gratifying peak power density of196 mW/cm^(2),and extraordinary long-term stability,outperforming the benchmark 20%Pt/C.展开更多
文摘研制高活性的Fe/N/C氧还原催化剂对于降低燃料电池成本、实现商业化应用有重要意义.为实现Fe/N/C催化剂的理性设计,需要深入研究其活性位结构.本文发展一种研究活性位结构的新策略,以预先合成好的聚间苯二胺基Fe/N/C催化剂(Pm PDA-Fe Nx/C)为起始物,对其在1000~1500 o C高温下再次进行热处理并使其失活,通过关联催化剂热处理前后的结构变化与氧还原催化性能来揭示活性位结构.实验结果表明,随着热处理温度升高,活性中心结构被破坏,铁原子析出团聚并形成纳米颗粒,氮元素挥发损失,导致催化剂失活.XPS分析显示,低结合能含氮物种的含量与催化剂的ORR活性呈良好的正相关性,表明活性中心很可能是由吡啶N和Fe-N物种构成的.
基金supported by the National Basic Research Program of Chain(973 Program,2015CB932300)the National Natural Science Foundation of China(21373175,21321062,21361140374)Fundamental Research Funds for the Central Universities(20720150109)
文摘Fe/N/C is a promising non-platinum catalyst for the oxygen reduction reaction （ORR）. Even so, mass transfer remains a challenge in the application of Fe/N/C to proton exchange membrane fuel cells, due to the high catalyst loadings required. In the present work, mesoporous Fe/N/C was syn- thesized through heat treatment of K]600 carbon black coated with poly-2-aminobenzimidazole and FeC13. The as-prepared Fe/N/C possesses a unique hollow-shell structure that contains a buffer zone allowing both water formation and vaporization, and also facilitates the mass transfer of gas- eous oxygen. This catalyst generated an oxygen reduction reaction activiW of 9.21 A/g in conjunc- tion with a peak power density of 0.71 W/cm2.
基金financially supported by the National Natural Science Foundation of China(21573167,21633008,91545205,21125312)National Key Research and Development Program(2016YFB0101203)+2 种基金the National Basic Research Program(2012CB932800,2012CB215500)the Doctoral Fund of Ministry of Education of China(20110141130002)the Fundamental Research Funds for the Central Universities(2014203020207)
文摘An environmentally friendly precursor, adenosine, has been used as a dual source of C and N to synthesize nitrogen-doped carbon catalyst with/without Fe. A hydrothermal carbonization method has been used and water is the carbonization media. The morphology of samples with/without Fe component has been compared by HRTEM, and the result shows that Fe can promote the graphitization of carbon. Further electro-chemical test shows that the oxygen reduction reaction（ORR） catalytic activity of Fe-containing sample（C–Fe N） is much higher than that of the Fe-free sample（C–N）. Additionally, the intermediates of C–Fe N formed during each synthetic procedure have been thoroughly characterized by multiple methods,and the function of each procedure has been discussed. The C–Fe N sample exhibits high electro-catalytic stability and superior electro-catalytic activity toward ORR in alkaline media, with its half-wave potential 20 mV lower than that of commercial Pt/C（40 wt%）. It is further incorporated into alkaline polymer electrolyte fuel cell（APEFC） as the cathode material and led to a power density of 100 m W/cm;.
基金financially supported by the Fundamental Re-search Funds for the Central Universities(No.2023CDJXY-016)the Outstanding Youth Project of Natural Science Foundation of Guangdong Province(Grant No.2022B1515020020).
文摘The state-of-the-art Fe/N/C catalyst has presented comparable initial cathode performance to the benchmark Pt/C catalyst in proton exchange membrane fuel cells(PEMFCs).However,the major bottleneck is its significant activity decay in real-world PEMFC cells.The superposed“fast decay”and“slow decay”have been well documented to describe the degradation process of Fe/N/C catalysts during PEMFC operation.The fast decay has been well understood in close relation to the demetallation at the initial 15-h stability test.Nevertheless,it is still unclear how the remanent active sites evolve after demetallation.To this end,the catalyst performance and evolution of a typical Fe/N/C active site were herein investigated through postmortem characterizations of the membrane electrode assemblies(MEAs)after different operations.It is presented that 1 bar pressure and 80℃ temperature are the optimized conditions for Fe/N/C MEA.Particularly,the“fast decay”in the initial 15 h is immune to the various operating parameters,while the“slow decay”highly depends on the applied temperature and pressure.According to the X-ray absorption spectra(XAS)analysis and stability test of MEA,the gradual evolution of Fe-N coordination to Fe-O is found correlated with the“slow decay”and accounts for the catalyst decay after the demetallation process.
基金the financial supports from National Natural Science Foundation of China(Nos.21971077,22071070)the facility support of the Center for Nanoscale Characterization&Devices(CNCD),WNLO of HUST,and the Analytical and Testing Center in Huazhong University of Science and Technology for all related measurements。
文摘The oxygen reduction reaction(ORR),an important process in Zn-air batteries(ZABs),shows sluggish reaction kinetics,which significantly impairs the further improvement of battery performance.Thus,rationally designing cathodic catalysts for ZABs has drawn sufficient attention.We herein synthesize and characterize Fe/N/F-tridoped CNTs(FeNFCs)by annealing the postsynthesized trifluoroacetic anhydridemodified Fe-MIL-88B-NH_(2)nanocrystals with melamine at high temperature in a N_(2)atmosphere.Benefiting from the Fe/N/F element doping,high specific surface area,and CNT structure,the FeNFC800 catalyst prepared at 800℃exhibits a preferable half-wave potential of 0.829 V vs.RHE.The Zn-air battery equipped with Fe NFC800 shows a high open-circuit voltage of 1.47 V,a gratifying peak power density of196 mW/cm^(2),and extraordinary long-term stability,outperforming the benchmark 20%Pt/C.
