Atomically FeN2 moieties dispersed on mesoporous carbon: A new atomic catalyst for efficient oxygen reduction catalysis

Han

et al. 2018

Small

237

161

The oxygen reduction reaction (ORR) plays an important role in the fields of energy storage and conversion technologies, including metal-air batteries and fuel cells. The development of nonprecious metal electrocatalysts with both high ORR activity and durability to replace the currently used costly Pt-based catalyst is critical and still a major challenge. Herein, a facile and scalable method is reported to prepare ZIF-8 with single ferrocene molecules trapped within its cavities (Fc@ZIF-8), which is utilized as precursor to porous single-atom Fe embedded nitrogen-doped carbon (Fe-N-C) during high temperature pyrolysis. The catalyst shows a half-wave potential (E ) of 0.904 V, 67 mV higher than commercial Pt/C catalyst (0.837 V), which is among the best compared with reported results for ORR. Significant electrochemical properties are attributed to the special configuration of Fc@ZIF-8 transforming into a highly dispersed iron-nitrogen coordination moieties embedded carbon matrix.

Section: Resultssupporting

confidence: 83%

Section: Introductionmentioning

confidence: 99%

ZIF‐8 with Ferrocene Encapsulated: A Promising Precursor to Single‐Atom Fe Embedded Nitrogen‐Doped Carbon as Highly Efficient Catalyst for Oxygen Electroreduction

Han

et al. 2018

Small

237

161

“…In 0.1 m KOH, the half‐wave potentials of the Fe‐ISAs/CN reached 0.9 V, which is 58 mV more positive than commercial Pt/C. Through DFT calculations, Shen et al suggested the FeN 2 configuration outperforms FeN 4 due to its lower interaction with *O 2 and *OH intermediates and enhanced electron transport (Figure d). Also, they prepared FeN 2 /NOMC catalysts with the N coordination number to be two, as confirmed by EXAFS and 57 Fe Mössbauer spectroscopy.…”

Section: Electrocatalytic Performancementioning

confidence: 99%

Modulating the Electronic Structure of Single‐Atom Catalysts on 2D Nanomaterials for Enhanced Electrocatalytic Performance

Zhu

Peng

et al. 2019

Small Methods

Single‐atom catalysts (SACs) on 2D nanomaterials have great potential as efficient and low‐cost electrocatalysts for clean energy technologies. The coordination environments, as well as the physicochemical properties of the 2D supports, play key roles in tuning the catalytic activity and reaction mechanism of the single‐atom centers. This review first summarizes the suitable synthetic strategies of single‐atom on different 2D supports. The methods that facilitate the formation of relative homogeneous structure and enable the regulation of the surrounding atomic environment of metal center are discussed. Furthermore, the recent progress of SACs for energy‐related electrochemical applications is reviewed, including oxygen reduction reaction, hydrogen evolution reaction, oxygen evolution reaction, CO2 reduction reaction, and nitrogen reduction reaction. The strategies about modulation of the electronic structure of single‐atom for enhanced performance are highlighted, together with a discussion of the current issues and the prospects of this field.

“…

Building metal-nitrogen moieties with unsaturated nitrogen coordination numbers to enhance material's catalytic activity remains a fundamental challenge.

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mentioning

confidence: 99%

“…[7][8][9][10] The short length scale of nanostructured catalysts makes it extremely challenging to quantify metal-nitrogen moiety structure and distributions and to correspondingly elucidate the electronic structure features and unusual activity. The state-of-the-art pyrolysis technique of specific precursors is commonly used to construct metal-nitrogen moieties.…”

mentioning

confidence: 99%

Metallic Porous Iron Nitride and Tantalum Nitride Single Crystals with Enhanced Electrocatalysis Performance

Zhang

Lin

et al. 2018

Advanced Materials

Previous studies show that the metalnitrogen moieties with unsaturated nitrogen coordination numbers possess higher catalytic activities and the reported smallest nitrogen coordination number is confirmed to be ≈2 for Co-N 2 and Fe-N 2 moieties using extended X-ray absorption fine structure spectra analysis. [4][5][6] These results indeed give an in-depth insight at the atomic level into structural dependence of catalytic activity of metal nitride nanoparticles by closely correlating the average structural information with catalytic performances. However, the active metalnitrogen moieties confined at the surface layer of materials that host catalysis reactions still remain unclear.Building metal-nitrogen moieties with unsaturated nitrogen coordination numbers to enhance material's catalytic activity remains a fundamental challenge. The state-of-the-art pyrolysis technique of specific precursors is commonly used to construct metal-nitrogen moieties. However, the simultaneous presence of multiple metal species in most composite catalysts makes it highly complex to understand the nature of metal-nitrogen moieties. [7][8][9][10] The short length scale of nanostructured catalysts makes it extremely challenging to quantify metal-nitrogen moiety structure and distributions and to correspondingly elucidate the electronic structure features and unusual activity. The metal-nitrogen moieties are indeed a kind of active clusters at atomic level, which are strictly confined at lattice in local structures in crystalline composites. The polycrystalline or amorphous states of composites make it highly uncertain to construct resolved metal-nitrogen moieties and to accordingly expose these active centers on material's surfaces to host catalysis reactions. Another consideration should be given to the resolved structural feature and chemical composition of moieties that tailor electronic structures to facilitate catalysis functionalities.Single crystals with porosity, combining the advantages of long-range structural coherence of bulk crystals and large surface areas of porous materials, could provide opportunities to host the metal-nitrogen moieties with unsaturated nitrogen coordination on surface. The long-range structural coherence in single crystals offers the possibility to stabilize the metalnitrogen moieties in lattice of local structures on crystalline surfaces especially on the condition that the surface moieties have similar chemical compositions to bulk crystals. Porous Altering a material's catalytic properties would require identifying structural features that deliver electrochemically active surfaces. Single-crystalline porous materials, combining the advantages of long-range ordering of bulk crystals and large surface areas of porous materials, would create sufficient active surfaces by stabilizing 2D active moieties confined in lattice and may provide an alternative way to create high-energy surfaces for electrocatalysis that are kinetically trapped. Here, a radical concept of building active metalnitrogen moieties ...