Evolution of atomic-scale dispersion of FeNx in hierarchically porous 3D air electrode to boost the interfacial electrocatalysis of oxygen reduction in PEMFC

Fu, Xiaogang; Gao, Rui; Jiang, Gaopeng; Li, Matthew; Li, Shuang; Luo, Dan; Hu, Yongfeng; Qin, Yuan; Huang, Wanxia; Zhu, Ning; Yang, Lin; Mao, Zhiyu; Xiong, Junwei; Yu, Aiping; Chen, Zhongwei; Bai, Zhengyu

doi:10.1016/j.nanoen.2020.105734

Cited by 45 publications

(28 citation statements)

References 52 publications

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“…Two characteristic peaks at 23 and 44° are observed, corresponding to the (002 and 101) diffraction peaks of carbon, respectively, indicating that the sample has been successfully carbonized after pyrolysis. It is worth noting that the Fe/NC catalyst pattern has diffraction peaks corresponding to iron oxide and iron carbide, which may be caused by inferior dispersion of Fe atom, while the Fe/SNC catalyst does not show any diffraction peaks related to crystalline iron, suggesting that the Fe species of Fe/SNC are highly dispersed on the MOF skeleton by doping S atom …”

Section: Resultsmentioning

confidence: 99%

Facile Method to Synthesize a High-Activity S-Doped Fe/SNC Single-Atom Catalyst by Metal–Organic Frameworks for Oxygen Reduction Reaction in Acidic Medium

et al. 2021

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Fe/NC single-atom catalysts containing atomically dispersed FeN4 moieties have exhibited encouraging activity comparable to that of Pt in aqueous acids and outstanding performance in practical proton exchange membrane fuel cells (PEMFCs). However, it is still challenging to design dispersive exposed Fe single atoms against agglomeration and tune Fe–N x coordination configuration to maximize the intrinsic activity of each active site. Introducing a heteroatom, such as S, could effectively improve the activity of the Fe/NC catalyst. In this work, we synthesized a novel catalyst (denoted as Fe/SNC) by pyrolyzing Fe(SCN)3 and ZIF-8 precursors under media conditions. This in situ S-doped catalyst showed better activity (half-wave potential positively shifted by 25 mV) and stability (improved 18%) compared to the Fe/NC catalyst in 0.5M H2SO4 solution.

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Section: Resultsmentioning

confidence: 99%

Facile Method to Synthesize a High-Activity S-Doped Fe/SNC Single-Atom Catalyst by Metal–Organic Frameworks for Oxygen Reduction Reaction in Acidic Medium

et al. 2021

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“…Moreover, to further verify the superior ORR activity of the edge Fe–N–C catalysts, Xiao et al synthesized single-atom FeN 4 edge-sites dominated graphene sheet . Furthermore, rich-edge Fe–N–C catalysts possess tunable micro-mesoporous structures and enlarged exposure of internal active sites. − Most importantly, the electronic structure of Fe–N–C active centers can be tuned by the encompassing coordination atoms, bringing about boosted catalytic activity. − Our group utilized sulfuration to promote the catalytic activity of the Fe–N–C catalytic system with embedded Fe–N–C and Fe–S species . However, producing a structure without directly bonding both heteroatoms and the center metal atoms or the coordinated atoms has remained scarce.…”

Section: Introductionmentioning

confidence: 99%

Phosphorus-Driven Electron Delocalization on Edge-Type FeN₄ Active Sites for Oxygen Reduction in Acid Medium

et al. 2021

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Precise tuning of the chemical environment of neighboring atomic FeN 4 sites is extremely important for optimizing Fe−N−C catalysts to produce the fast oxygen reduction reaction (ORR) kinetics both in acidic and alkaline media, but it is actually very challenging. Heteroatoms could affect the metal charge of the active center through long-range electron delocalization; however, there are a few studies on it. Herein, density functional theory (DFT) calculations demonstrate that the addition of long-range P into edge-type FeN 4 can drive the electron delocalization and decrease the band gap of the FeN 4 center, leading to a substantial decrease in the free energy barrier to direct four-electron ORR kinetics compared to P-free edge-type FeN 4 , indicating superior intrinsic ORR activity. Experimentally, by incorporating P in edge-rich FeN 4 supported on N,P-doped carbon (Fe−N−C−P/N,P−C), the created Fe−N−C catalyst presents the greatly increased acidic ORR activity, with a half-wave potential (E 1/2 ) of 0.80 V (vs a reversible hydrogen electrode), which approaches that of commercial Pt/C and also has a high half-wave potential of 0.87 V, beyond Pt/C for alkaline ORR. In addition, it shows higher proton exchange membrane fuel cell and Zn-air battery performances than the pristine Fe−C−N catalyst (Fe−N−C/ N−C). This work will guide the rational design of highly active metal atomic scale catalysts with optimized chemical surroundings in terms of P incorporation as a chemically tunable method.

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“…fabricated single atom FeN x active sites rooted in porous carbon microspheres via spray‐carbonization treatment, zeolitic imidazolate frameworks, and subsequent FeN x sites incorporation operation. [ 18 ] Benefitting from the enhanced intrinsic catalytic activity and effective mass transfer, such materials when applied as catalysts of air cathode, boosted the fuel cell performance. Unfortunately, there remain two challenges influencing the high performance of M–N–C catalysts.…”

Section: Introductionmentioning

confidence: 99%

“…[ 19 ] Second, the majority of the active catalytic sites embedded in the carbon framework are inaccessible, making mass exchange and electron transfer processes ineffective. [ 18,20 ] Therefore, synthesis of M–N–C materials with high MN x loadings and fully accessible active sites is crucial to boost ORR performance. [ 21 ]…”

Section: Introductionmentioning

confidence: 99%

Electrospun Carbon Nanofibers Loaded with Atomic FeN_x/Fe₂O₃ Active Sites for Efficient Oxygen Reduction Reaction in Both Acidic and Alkaline Media

Wang

Liao

Zhang

et al. 2022

Adv Materials Inter

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Renewable energy storage systems based on oxygen reduction reaction (ORR) call for high‐performance, durable, and low‐cost electrocatalysts. However, practical applications of ORR catalysts available today are hampered by the inability to load accessible catalytic sites efficiently. Herein, a novel and efficient ORR electrocatalyst (Fe2O3/FeNx@CNF) with atomic FeNx sites and neighboring Fe2O3 nanoparticles embedded in interconnected carbon nanofibers prepared via electrospinning is reported. Detailed material characterizations confirm that the as‐prepared catalysts possess a well‐defined fibrous structure with hierarchical pores, large specific surface area, and uniformly distributed Fe2O3/FeNx active sites. Further, it exhibits excellent ORR performance with high onset potential, half‐wave potential, and current density in both alkaline and acidic media. And these electrocatalysts show excellent long‐term performance and tolerance to methanol, exceeding the properties of commercial platinum catalysts. Additionally, the Fe2O3/FeNx@CNF electrocatalyst prepared in this study exhibits high discharge voltage, excellent power density, and cycling durability in Zn–air batteries. Notably, the detailed analyses demonstrate the co‐existence of Fe2O3 nanoparticles and FeNx active sites boost the ORR catalytic activity of the hybrid catalyst. These new findings, particularly the enhancement of intrinsic activity of FeNx sites brought about by Fe2O3 nanoparticles, provide insights into the rational design of hybrid single‐atom ORR electrocatalysts.

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Evolution of atomic-scale dispersion of FeNx in hierarchically porous 3D air electrode to boost the interfacial electrocatalysis of oxygen reduction in PEMFC

Cited by 45 publications

References 52 publications

Facile Method to Synthesize a High-Activity S-Doped Fe/SNC Single-Atom Catalyst by Metal–Organic Frameworks for Oxygen Reduction Reaction in Acidic Medium

Facile Method to Synthesize a High-Activity S-Doped Fe/SNC Single-Atom Catalyst by Metal–Organic Frameworks for Oxygen Reduction Reaction in Acidic Medium

Phosphorus-Driven Electron Delocalization on Edge-Type FeN₄ Active Sites for Oxygen Reduction in Acid Medium

Electrospun Carbon Nanofibers Loaded with Atomic FeN_x/Fe₂O₃ Active Sites for Efficient Oxygen Reduction Reaction in Both Acidic and Alkaline Media

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Evolution of atomic-scale dispersion of FeNx in hierarchically porous 3D air electrode to boost the interfacial electrocatalysis of oxygen reduction in PEMFC

Cited by 45 publications

References 52 publications

Facile Method to Synthesize a High-Activity S-Doped Fe/SNC Single-Atom Catalyst by Metal–Organic Frameworks for Oxygen Reduction Reaction in Acidic Medium

Facile Method to Synthesize a High-Activity S-Doped Fe/SNC Single-Atom Catalyst by Metal–Organic Frameworks for Oxygen Reduction Reaction in Acidic Medium

Phosphorus-Driven Electron Delocalization on Edge-Type FeN4 Active Sites for Oxygen Reduction in Acid Medium

Electrospun Carbon Nanofibers Loaded with Atomic FeNx/Fe2O3 Active Sites for Efficient Oxygen Reduction Reaction in Both Acidic and Alkaline Media

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Resources

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Phosphorus-Driven Electron Delocalization on Edge-Type FeN₄ Active Sites for Oxygen Reduction in Acid Medium

Electrospun Carbon Nanofibers Loaded with Atomic FeN_x/Fe₂O₃ Active Sites for Efficient Oxygen Reduction Reaction in Both Acidic and Alkaline Media