【摘 要】
:
In this study,we aim to contribute an understanding of the pathway of formation of Fe species during top-down synthesis of dispersed Fe on N-functionalized few layer graphene,widely used in electrocatal-ysis.We use X-ray absorption spectroscopy to determi
【机 构】
:
School of Science,Engineering and Environment,University of Salford,Manchester M54WT,UK;Diamond Ligh
论文部分内容阅读
In this study,we aim to contribute an understanding of the pathway of formation of Fe species during top-down synthesis of dispersed Fe on N-functionalized few layer graphene,widely used in electrocatal-ysis.We use X-ray absorption spectroscopy to determine the electronic structure and coordination geom-etry of the Fe species and in situ high angle annular dark field scanning transmission electron microscopy combined with atomic resolved electron energy loss spectroscopy to localize these,identify their chem-ical configuration and monitor their dynamics during thermal annealing.We show the high mobility of peripheral Fe atoms,first diffusing rapidly at the trims of the graphene layers and at temperatures as high as 573 K,diffusing from the edge planes towards in-plane locations of the graphene layers forming three-,four-coordinated metal sites and more complexes polynuclear Fe species.This process occurs via bond C-C breaking which partially reduces the extension of the graphene domains.However,the vast majority of Fe is segregated as a metal phase.This dynamic interconversion depends on the structural details of the surrounding graphitic environment in which these are formed as well as the Fe loading.N species appear stabilizing isolated and polynuclear Fe species even at temperatures as high as 873 K.The signif-icance of our results lies on the fact that single Fe atoms in graphene are highly mobile and therefore a structural description of the electroactive sites as such is insufficient and more complex species might be more relevant,especially in the case of multielectron transfer reactions.Here we provide the experimen-tal evidence of the formation of these polynuclear Fe-N sites and their structural characteristics.
其他文献
Rechargeable aluminum batteries are believed as a promising next-generation energy-storage system due to abundant low-cost Al sources and high volumetric specific capacity.The Al-storage cathodes,how-ever,are plagued by strong electrostatic interaction be
Practical implementations of rechargeable lithium (Li) metal batteries have long been plagued by multi-ple problems of Li anode,such as Li dendrite growth,large volume change,low Coulombic efficiency.Here,we report a protein-enabled film that can provide
The replacement of small cations with bulkier organic cations containing long alkyl chains or benzene rings to form a thin two-dimensional (2D) perovskite passivation layer on three-dimensional (3D) per-ovskite (2D/3D) has become a promising strategy for
Perovskite BaTaO2N (BTON) is one of the most promising photocatalysts for solar water splitting due to its wide visible-light absorption and suitable conduction/valence bands,but it still confronts the chal-lenge of high defect density causing decreased c
Li-CO2 batteries provide an attractive and potential strategy for CO2 utilization as well as energy conversion and storage with high specific energy densities.However,the poor reversibility caused by the decomposition obstacles of Li2CO3 and C products is
Metal-organic frameworks (MOFs) have been widely studied as efficient electrocatalysts for water oxida-tion due to their tunable structure and easy preparation.However,the rational design of MOFs-based electrocatalysts and fundamental understanding of the
Bulk and interface carrier nonradiative recombination losses impede the further improvement of power conversion efficiency (PCE) and stability of perovskite solar cells (PSCs).It is highly necessary to develop multifunctional strategy to minimize surface
The hybridization between the outmost s orbitals of metal (Bi3+,Sn2+,Pb2+,Ag+) and O 2p orbitals has been widely employed to develop innovative semiconductors with upshift valence band as well as extended visible light response,but it is still challenging
Perovskite solar cells (PSCs) have emerged as a new-generation photovoltaic technology that features both low manufacturing cost and high power conversion efficiencies (PCEs) [1-3].In the past decade,the PCEs of PSCs have increased from 3.8% to 25.5%,whic
Two-dimensional carbon nitride (2D-C3N4) nanosheets are promising materials in photocatalytic water splitting,but still suffer from easy agglomeration and fast photogenerated electron-hole pairs recombi-nation.To tackle this issue,herein,a hierarchical Nb