Atomically dispersed nonmagnetic electron traps improve oxygen reduction activity of perovskite oxides

Nonmagnetic hexavalent molybdenum atomically dispersed within oxide lattice steers the intrinsic oxygen reduction activity of catalytically active sites, and excludes the occurrence of lattice symmetry breaking and magnetic perturbation.

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Substrate strain tunes operando geometric distortion and oxygen reduction activity of CuN2C2 single-atom sites

Nature Communications ◽

10.1038/s41467-021-26747-1 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Guokang Han ◽

Xue Zhang ◽

Wei Liu ◽

Qinghua Zhang ◽

Zhiqiang Wang ◽

...

Keyword(s):

Structure Function ◽

Oxygen Reduction ◽

Active Sites ◽

Geometric Distortion ◽

Single Atom ◽

Reduction Activity ◽

Activity Promotion ◽

Structure Function Relationship ◽

Substrate Strain ◽

Function Relationship

AbstractSingle-atom catalysts are becoming increasingly significant to numerous energy conversion reactions. However, their rational design and construction remain quite challenging due to the poorly understood structure–function relationship. Here we demonstrate the dynamic behavior of CuN2C2 site during operando oxygen reduction reaction, revealing a substrate-strain tuned geometry distortion of active sites and its correlation with the activity. Our best CuN2C2 site, on carbon nanotube with 8 nm diameter, delivers a sixfold activity promotion relative to graphene. Density functional theory and X-ray absorption spectroscopy reveal that reasonable substrate strain allows the optimized distortion, where Cu bonds strongly with the oxygen species while maintaining intimate coordination with C/N atoms. The optimized distortion facilitates the electron transfer from Cu to the adsorbed O, greatly boosting the oxygen reduction activity. This work uncovers the structure–function relationship of single-atom catalysts in terms of carbon substrate, and provides guidance to their future design and activity promotion.

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Improving Oxygen Reduction Activity of the Iron-Nitrogen-Carbon Catalysts by Formation of Fruitful Active Sites

ECS Meeting Abstracts ◽

10.1149/ma2011-02/7/322 ◽

2011 ◽

Keyword(s):

Oxygen Reduction ◽

Active Sites ◽

Reduction Activity ◽

Carbon Catalysts

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Tuning the Fe-N4 sites by introducing Bi-O bond in Fe-N-C system for promoting oxygen reduction reaction

Journal of Materials Chemistry A ◽

10.1039/d1ta08256f ◽

2021 ◽

Author(s):

Huihui Jin ◽

Jiawei Zhu ◽

Ruohan Yu ◽

Wenqiang Li ◽

Pengxia Ji ◽

...

Keyword(s):

Oxygen Reduction Reaction ◽

Oxygen Reduction ◽

Electrocatalytic Activity ◽

Noble Metals ◽

Perovskite Oxides ◽

Reduction Reaction ◽

Reduction Activity

Elemental Bi is effective in optimizing the electrocatalytic activity of perovskite oxides and noble metals, but has never been used to adjust the oxygen reduction activity of Fe/N-C catalysts. Here,...

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Design Principles for Oxygen Reduction Activity on Perovskite Oxides in Alkaline Environment

ECS Meeting Abstracts ◽

10.1149/ma2011-02/16/1063 ◽

2011 ◽

Keyword(s):

Oxygen Reduction ◽

Design Principles ◽

Perovskite Oxides ◽

Alkaline Environment ◽

Reduction Activity

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Regulating Fe-spin state by atomically dispersed Mn-N in Fe-N-C catalysts with high oxygen reduction activity

Nature Communications ◽

10.1038/s41467-021-21919-5 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Gege Yang ◽

Jiawei Zhu ◽

Pengfei Yuan ◽

Yongfeng Hu ◽

Gan Qu ◽

...

Keyword(s):

Oxygen Reduction Reaction ◽

Oxygen Reduction ◽

Spin State ◽

Active Sites ◽

Rational Design ◽

Magnetic Measurements ◽

Low Cost ◽

Reduction Reaction ◽

Model Object ◽

Reduction Activity

AbstractAs low-cost electrocatalysts for oxygen reduction reaction applied to fuel cells and metal-air batteries, atomic-dispersed transition metal-nitrogen-carbon materials are emerging, but the genuine mechanism thereof is still arguable. Herein, by rational design and synthesis of dual-metal atomically dispersed Fe,Mn/N-C catalyst as model object, we unravel that the O2 reduction preferentially takes place on FeIII in the FeN4 /C system with intermediate spin state which possesses one eg electron (t2g4eg1) readily penetrating the antibonding π-orbital of oxygen. Both magnetic measurements and theoretical calculation reveal that the adjacent atomically dispersed Mn-N moieties can effectively activate the FeIII sites by both spin-state transition and electronic modulation, rendering the excellent ORR performances of Fe,Mn/N-C in both alkaline and acidic media (halfwave positionals are 0.928 V in 0.1 M KOH, and 0.804 V in 0.1 M HClO4), and good durability, which outperforms and has almost the same activity of commercial Pt/C, respectively. In addition, it presents a superior power density of 160.8 mW cm−2 and long-term durability in reversible zinc–air batteries. The work brings new insight into the oxygen reduction reaction process on the metal-nitrogen-carbon active sites, undoubtedly leading the exploration towards high effective low-cost non-precious catalysts.

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Emergence of Oxygen Reduction Activity in Zirconium Oxide-Based Compounds in Acidic Media: Creation of Active Sites for the Oxygen Reduction Reaction

The Journal of Physical Chemistry C ◽

10.1021/acs.jpcc.9b02393 ◽

2019 ◽

Vol 123 (30) ◽

pp. 18150-18159 ◽

Cited By ~ 5

Author(s):

Akimitsu Ishihara ◽

Takaaki Nagai ◽

Keisuke Ukita ◽

Masazumi Arao ◽

Masashi Matsumoto ◽

...

Keyword(s):

Oxygen Reduction Reaction ◽

Oxygen Reduction ◽

Zirconium Oxide ◽

Active Sites ◽

Reduction Reaction ◽

Acidic Media ◽

Reduction Activity ◽

Media Creation

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Co,N-codoped nanotube/graphene 1D/2D heterostructure for efficient oxygen reduction and hydrogen evolution reactions

Journal of Materials Chemistry A ◽

10.1039/c7ta11140a ◽

2018 ◽

Vol 6 (9) ◽

pp. 3926-3932 ◽

Cited By ~ 77

Author(s):

Liu Yang ◽

Yanlong Lv ◽

Dapeng Cao

Keyword(s):

Oxygen Reduction ◽

Hydrogen Evolution ◽

Active Sites ◽

New Approach ◽

Multifunctional Catalysts ◽

Catalytically Active ◽

Hydrogen Evolution Reactions

This work provides a new approach for the in situ synthesis of bifunctional and multifunctional catalysts by integrating 1D/2D/3D materials with different catalytically active sites into one heterostructure.

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Improved oxygen reduction activity of carbon nanotubes and graphene through adenine functionalization

RSC Advances ◽

10.1039/c7ra02865b ◽

2017 ◽

Vol 7 (43) ◽

pp. 26722-26728 ◽

Cited By ~ 4

Author(s):

Youze Xu ◽

Caili Chen ◽

Mo Zhou ◽

Guangyi FU ◽

Yuanyuan Zhao ◽

...

Keyword(s):

Carbon Nanotubes ◽

Oxygen Reduction ◽

Active Sites ◽

Carbon Materials ◽

Nitrogen Species ◽

Reduction Activity

The SWNT or graphene can draw electrons from the nitrogen species in adenine to form pyrrolic/graphitic-N-type groups as ORR active sites, similar with that of N-doped carbon materials, offering an opportunity to develop a class of new ORR catalysts.

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A Pyridinic Fe-N4 Macrocycle Effectively Models the Active Sites in Fe/N-Doped Carbon Electrocatalysts

10.26434/chemrxiv.10008545.v2 ◽

2020 ◽

Author(s):

Travis Marshall-Roth ◽

Nicole J. Libretto ◽

Alexandra T. Wrobel ◽

Kevin Anderton ◽

Nathan D. Ricke ◽

...

Keyword(s):

Oxygen Reduction ◽

Active Sites ◽

Catalytic Properties ◽

Reduction Reaction ◽

Iron Phthalocyanine ◽

Electrochemical Studies ◽

Onset Potential ◽

Nitrogen Doped Carbon ◽

Iron Active Sites

Iron- and nitrogen-doped carbon (Fe-N-C) materials are leading candidates to replace platinum in fuel cells, but their active site structures are poorly understood. A leading postulate is that iron active sites in this class of materials exist in an Fe-N4 pyridinic ligation environment. Yet, molecular Fe-based catalysts for the oxygen reduction reaction (ORR) generally feature pyrrolic coordination and pyridinic Fe-N4 catalysts are, to the best of our knowledge, non-existent. We report the synthesis and characterization of a molecular pyridinic hexaazacyclophane macrocycle, (phen2N2)Fe, and compare its spectroscopic, electrochemical, and catalytic properties for oxygen reduction to a prototypical Fe-N-C material, as well as iron phthalocyanine, (Pc)Fe, and iron octaethylporphyrin, (OEP)Fe, prototypical pyrrolic iron macrocycles. N 1s XPS signatures for coordinated N atoms in (phen2N2)Fe are positively shifted relative to (Pc)Fe and (OEP)Fe, and overlay with those of Fe-N-C. Likewise, spectroscopic XAS signatures of (phen2N2)Fe are distinct from those of both (Pc)Fe and (OEP)Fe, and are remarkably similar to those of Fe-N-C with compressed Fe–N bond lengths of 1.97 Å in (phen2N2)Fe that are close to the average 1.94 Å length in Fe-N-C. Electrochemical studies establish that both (Pc)Fe and (phen2N2)Fe have relatively high Fe(III/II) potentials at ~0.6 V, ~300 mV positive of (OEP)Fe. The ORR onset potential is found to directly correlate with the Fe(III/II) potential leading to a ~300 mV positive shift in the onset of ORR for (Pc)Fe and (phen2N2)Fe relative to (OEP)Fe. Consequently, the ORR onset for (phen2N2)Fe and (Pc)Fe is within 150 mV of Fe-N-C. Unlike (OEP)Fe and (Pc)Fe, (phen2N2)Fe displays excellent selectivity for 4-electron ORR with <4% maximum H2O2 production, comparable to Fe-N-C materials. The aggregate spectroscopic and electrochemical data establish (phen2N2)Fe as a pyridinic iron macrocycle that effectively models Fe-N-C active sites, thereby providing a rich molecular platform for understanding this important class of catalytic materials.

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