The keen interest in fuel cells and metal-air batteries stimulates a great deal of research on the development of a cost-efficient and high-performance catalyst as an alternative to traditional Pt to boost the sluggis...The keen interest in fuel cells and metal-air batteries stimulates a great deal of research on the development of a cost-efficient and high-performance catalyst as an alternative to traditional Pt to boost the sluggish oxygen reduction reaction(ORR)at the cathode.Herein,we report a facile and scalable strategy for the large-scale preparation of a free-standing and flexible porous atomically dispersed Fe-N-doped carbon microtube(FeSAC/PCMT)sponge.Benefiting from its unique structure that greatly facilitates the catalytic kinetics,mass transport,and electron transfer,our FeSAC/PCMT electrode exhibits excellent performance with an ORR potential of 0.942 V at^(-3) mA cm^(-2).When the FeSAC/PCMT sponge was directly used as an oxygen electrode for liquid-state and flexible solid-state zinc-air batteries,high peak power densities of 183.1 and 58.0 mW cm^(-2) were respectively achieved,better than its powdery counterpart and commercial Pt/C catalyst.Experimental and theoretical investigation results demonstrate that such ultrahigh ORR performance can be attributed to atomically dispersed Fe-N_(5) species in FeSAC/PCMT.This study presents a cost-effective and scalable strategy for the fabrication of highly efficient and flexible oxygen electrodes,provides a significant new insight into the catalytic mechanisms,and helps to realize significant advances in energy devices.展开更多
Developing stable but high active metal-nitrogen-carbon(M-N-C)-based hard carbon anode is a promising way to be the alternatives to graphene and blank hard carbon for sodium-ion batteries(SIBs),requiring the precise t...Developing stable but high active metal-nitrogen-carbon(M-N-C)-based hard carbon anode is a promising way to be the alternatives to graphene and blank hard carbon for sodium-ion batteries(SIBs),requiring the precise tailoring of the electronic structure for optimizing the Na+intercalation behavior,yet is greatly challenging.Herein,Fe-N-C graphitic layer-encapsulating Fe3C species within hard carbon nanosheets(Fe-N-C/Fe3C@HCNs)are rationally engineered by pyrolysis of self-assembled polymer.Impressively,the Fe-N-C/Fe3C@HCNs exhibit outstanding rate capacity(242 mAh·g^(−1)at 2,000 mA·g^(−1)),which is 2.1 and 4.2 times higher than that of Fe-N-C and N-doped carbon(N-C),respectively,and prolonged cycling stability(176 mAh·g^(−1)at 2,000 mA·g^(−1)after 2,000 cycles).Theoretical calculations unveil that the Fe3C species enhance the electronic transfer from Na to Fe-N-C,resulting in the charge redistribution between the interfaces of Fe3C and Fe-N-C.Thus,the optimized adsorption behavior towards Na+reduces the thermodynamic energy barriers.The synergistic effect of Fe3C and Fe-N-C species maintains the structural integrity of electrode materials during the sodiation/desodiation process.The in-depth insight into the advanced Na+storage mechanisms of Fe3C@Fe-N-C offers precise guidance for the rational establishment of confinement heterostructures in SIBs.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 start-up fund from Kunming University of Science and Technology,the National Natural Science Foundation of China (Grants 52102046,51872293,52130209,52072375)Liaoning Revitalization Talents Program (XLYC2002037)Basic Research Project of Natural Science Foundation of Shandong Province,China (ZR2019ZD49).
文摘The keen interest in fuel cells and metal-air batteries stimulates a great deal of research on the development of a cost-efficient and high-performance catalyst as an alternative to traditional Pt to boost the sluggish oxygen reduction reaction(ORR)at the cathode.Herein,we report a facile and scalable strategy for the large-scale preparation of a free-standing and flexible porous atomically dispersed Fe-N-doped carbon microtube(FeSAC/PCMT)sponge.Benefiting from its unique structure that greatly facilitates the catalytic kinetics,mass transport,and electron transfer,our FeSAC/PCMT electrode exhibits excellent performance with an ORR potential of 0.942 V at^(-3) mA cm^(-2).When the FeSAC/PCMT sponge was directly used as an oxygen electrode for liquid-state and flexible solid-state zinc-air batteries,high peak power densities of 183.1 and 58.0 mW cm^(-2) were respectively achieved,better than its powdery counterpart and commercial Pt/C catalyst.Experimental and theoretical investigation results demonstrate that such ultrahigh ORR performance can be attributed to atomically dispersed Fe-N_(5) species in FeSAC/PCMT.This study presents a cost-effective and scalable strategy for the fabrication of highly efficient and flexible oxygen electrodes,provides a significant new insight into the catalytic mechanisms,and helps to realize significant advances in energy devices.
基金the National Key R&D Program of China(Nos.2016YFA0204100 and 2016YFA0200200)the National Natural Science Foundation of China(Nos.21890753,21988101,22162026,and 21875221)+2 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB36030200)the Danish company Haldor Topsøe A/S,the Youth Talent Support Program of High-Level Talents Special Support Plan in Henan Province(No.ZYQR201810148)Creative talents in the Education Department of Henan Province(No.19HASTIT039).
文摘Developing stable but high active metal-nitrogen-carbon(M-N-C)-based hard carbon anode is a promising way to be the alternatives to graphene and blank hard carbon for sodium-ion batteries(SIBs),requiring the precise tailoring of the electronic structure for optimizing the Na+intercalation behavior,yet is greatly challenging.Herein,Fe-N-C graphitic layer-encapsulating Fe3C species within hard carbon nanosheets(Fe-N-C/Fe3C@HCNs)are rationally engineered by pyrolysis of self-assembled polymer.Impressively,the Fe-N-C/Fe3C@HCNs exhibit outstanding rate capacity(242 mAh·g^(−1)at 2,000 mA·g^(−1)),which is 2.1 and 4.2 times higher than that of Fe-N-C and N-doped carbon(N-C),respectively,and prolonged cycling stability(176 mAh·g^(−1)at 2,000 mA·g^(−1)after 2,000 cycles).Theoretical calculations unveil that the Fe3C species enhance the electronic transfer from Na to Fe-N-C,resulting in the charge redistribution between the interfaces of Fe3C and Fe-N-C.Thus,the optimized adsorption behavior towards Na+reduces the thermodynamic energy barriers.The synergistic effect of Fe3C and Fe-N-C species maintains the structural integrity of electrode materials during the sodiation/desodiation process.The in-depth insight into the advanced Na+storage mechanisms of Fe3C@Fe-N-C offers precise guidance for the rational establishment of confinement heterostructures in SIBs.
