Iron Atom-Cluster Strategy Synthesis of Hierarchically Porous Fe–N–C Catalysts for Proton Exchange Membrane Fuel Cells

Abstract

Developing nonprecious metal-nitrogen-doped carbon (M–N–C) catalysts with high activity and stability is critical to their widespread use in fuel cells; however, these catalysts still face considerable challenges. Herein, a novel iron atom-cluster strategy for the synthesis of iron-based N–C catalyst comprising Fe nanoparticles (Fe NPs) surrounded by Fe-N _x sites is developed for oxygen reduction reactions in an acidic fuel cell. Iron oxide NPs were incorporated into zeolitic imidazolate framework-8 (ZIF-8)-derived carbon materials and pyrolyzed at high temperatures using NaCl as a modifier to produce Fe NPs and Fe-N _x composite active sites. The half-wave potential of the optimized Fe_NP/FeNC-NaCl material was substantially improved to 0.81 V. Furthermore, even after 15,000 cycles, the half-wave potential of the catalyst remained essentially unchanged. As a cathode catalyst for fuel cells, it realized a high peak power density of 436 mW/cm² under a practical H₂-air atmosphere. Therefore, this study presents a new approach for designing and synthesizing electrocatalytic materials with high catalytic activity and stability.

Keywords

Oxygen reduction reaction / Fuel cell / Fe–N-doped carbon / Iron atom clusters / Pyrolysis synthesis

References

[1] Armeanu D, Gherghina SC, Pasmangiu G Exploring the causal nexus between energy consumption, environmental pollution and economic growth: empirical evidence from central and eastern Europe. Energies, 2019, 12(19

[2] Balat M, Ayar G, Oguzhan C, et al. Influence of fossil energy applications on environmental pollution. Energy Sour Part B Econ Plan Policy, 2007, 2(3): 213-226.

[3] Anser MK, Hanif I, Vo XV, et al. The long-run and short-run influence of environmental pollution, energy consumption, and economic activities on health quality in emerging countries. Environ Sci Pollut Res Int, 2020, 27(26): 32518-32532.

[4] Samad S, Loh KS, Wong WY, et al. Carbon and non–carbon support materials for platinum-based catalysts in fuel cells. Int J Hydrog Energy, 2018, 43(16): 7823-7854.

[5] Guo Y, Pan F, Chen W, et al. The controllable design of catalyst inks to enhance PEMFC performance: a review. Electrochem Energy Rev, 2021, 4(1): 67-100.

[6] Yu X, Ye S Recent advances in activity and durability enhancement of Pt/C catalytic cathode in PEMFC. J Power Sour, 2007, 172(1): 145-154.

[7] Zhang L, Fischer JMTA, Jia Y, et al. Coordination of atomic Co-Pt coupling species at carbon defects as active sites for oxygen reduction reaction. J Am Chem Soc, 2018, 140(34): 10757-10763.

[8] Debe MK Electrocatalyst approaches and challenges for automotive fuel cells. Nature, 2012, 486(7401): 43-51.

[9] Tasic GS, Miljanic SS, Marceta Kaninski MP, et al. Non-noble metal catalyst for a future Pt free PEMFC. Electrochem Commun, 2009, 11(11): 2097-2100.

[10] Cho YH, Park HS, Cho YH, et al. Effect of platinum amount in carbon supported platinum catalyst on performance of polymer electrolyte membrane fuel cell. J Power Sour, 2007, 172(1): 89-93.

[11] Litster S, McLean G PEM fuel cell electrodes. J Power Sour, 2004, 130(1–2): 61-76.

[12] He Y, Tan Q, Lu L, et al. Metal-nitrogen–carbon catalysts for oxygen reduction in PEM fuel cells: self-template synthesis approach to enhancing catalytic activity and stability. Electrochem Energy Rev, 2019, 2(2): 231-251.

[13] Wang XX, Swihart MT, Wu G Achievements, challenges and perspectives on cathode catalysts in proton exchange membrane fuel cells for transportation. Nat Catal, 2019, 2(7): 578-589.

[14] Hou Y, Huang T, Wen Z, et al. Metal–organic framework-derived nitrogen-doped core-shell-structured porous Fe/Fe₃C@C nanoboxes supported on graphene sheets for efficient oxygen reduction reactions. Adv Energy Mater, 2014, 4(11): 1400337.

[15] Xiao M, Zhu J, Ma L, et al. Microporous framework induced synthesis of single-atom dispersed Fe–N–C acidic ORR catalyst and its in situ reduced Fe-N₄ active site identification revealed by X-ray absorption spectroscopy. ACS Catal, 2018, 8(4): 2824-2832.

[16] Yang X, Xia D, Kang Y, et al. Unveiling the axial hydroxyl ligand on Fe-N₄-C electrocatalysts and its impact on the pH-dependent oxygen reduction activities and poisoning kinetics. Adv Sci, 2020, 7(12): 2000176.

[17] Zhong R, Zhi C, Wu Y, et al. Atomic Fe-N₄ sites on electrospun hierarchical porous carbon nanofibers as an efficient electrocatalyst for oxygen reduction reaction. Chin Chem Lett, 2020, 31(6): 1588-1592.

[18] Jiao L, Li J, Richard LL, et al. Chemical vapour deposition of Fe–N–C oxygen reduction catalysts with full utilization of dense Fe-N₄ sites. Nat Mater, 2021, 20(10): 1385-1391.

[19] Chen G, Liu P, Liao Z, et al. Zinc-mediated template synthesis of Fe–N–C electrocatalysts with densely accessible Fe-N _x active sites for efficient oxygen reduction. Adv Mater, 2020, 32(8

[20] Xiao T, Wang Y, Wan J, et al. Fe–N–C catalyst with Fe-N _x sites anchored nano carboncubes derived from Fe-Zn-MOFs activate peroxymonosulfate for high-effective degradation of ciprofloxacin: thermal activation and catalytic mechanism. J Hazard Mater, 2022, 424(Pt A

[21] Zou D, Liu D, Zhang J From zeolitic imidazolate framework-8 to metal-organic frameworks (MOFs):representative substance for the general study of pioneering MOF applications. Energy Environ Mater, 2018, 1(4): 209-220.

[22] Zhang H, Chung HT, Cullen DA, et al. High-performance fuel cell cathodes exclusively containing atomically dispersed iron active sites. Energy Environ Sci, 2019, 12(8): 2548-2558.

[23] Liu B, Yao H, Song W, et al. Ligand-free noble metal nanocluster catalysts on carbon supports via soft nitriding. J Am Chem Soc, 2016, 138(14): 4718-4721.

[24] Wang Y, Su H, He Y, et al. Advanced electrocatalysts with single-metal-atom active sites. Chem Rev, 2020, 120(21): 12217-12314.

[25] Wang B, Wang X, Zou J, et al. Simple-cubic carbon frameworks with atomically dispersed iron dopants toward high-efficiency oxygen reduction. Nano Lett, 2017, 17(3): 2003-2009.

[26] Liu Q, Liu X, Zheng L, et al. The solid-phase synthesis of an Fe–N–C electrocatalyst for high-power proton-exchange membrane fuel cells. Angew Chem Int Ed Engl, 2018, 57(5): 1204-1208.

[27] Wang Q, Yang Y, Sun F, et al. Molten NaCl-assisted synthesis of porous Fe–N–C electrocatalysts with a high density of catalytically accessible FeN₄Active sites and outstanding oxygen reduction reaction performance. Adv Energy Mater, 2021, 11(19): 2100219.

[28] Yang T, Li N, Wei D, et al. NaCl-assisted synthesis of 2D hexagonal FeNC nanosheets as efficient oxygen reduction catalyst for metal-air batteries. J Electroanal Chem, 2023, 941.

[29] Zhao SN, Li JK, Wang R, et al. Electronically and geometrically modified single-atom Fe sites by adjacent Fe nanoparticles for enhanced oxygen reduction. Adv Mater, 2022, 34(5

[30] Ibraheem S, Chen S, Li J, et al. Three-dimensional Fe, N-decorated carbon-supported NiFeP nanoparticles as an efficient bifunctional catalyst for rechargeable zinc-O₂ batteries. ACS Appl Mater Interfaces, 2019, 11(1): 699-705.

[31] Choi CH, Baldizzone C, Grote JP, et al. Stability of Fe–N–C catalysts in acidic medium studied by operando spectroscopy. Angew Chem Int Ed Engl, 2015, 54(43): 12753-12757.

[32] Martinez U, Komini Babu S, Holby EF, et al. Durability challenges and perspective in the development of PGM-free electrocatalysts for the oxygen reduction reaction. Curr Opin Electrochem, 2018, 9: 224-232.

[33] Martinez U, Komini Babu S, Holby EF, et al. Progress in the development of Fe-based PGM-free electrocatalysts for the oxygen reduction reaction. Adv Mater, 2019, 31(31

[34] Gridin V, Kübler M, Hanstein T, et al. Influence of the addition of nanoparticles on the oxygen reduction reaction characteristics of FeNC catalysts and the impact on the stability. J Power Sour, 2023, 561.

[35] Choi CH, Lim HK, Chung MW, et al. The Achilles' heel of iron-based catalysts during oxygen reduction in an acidic medium. Energy Environ Sci, 2018, 11(11): 3176-3182.

[36] Kumar K, Dubau L, Mermoux M, et al. On the influence of oxygen on the degradation of Fe–N–C catalysts. Angew Chem Int Ed Engl, 2020, 59(8): 3235-3243.

[37] Wan X, Liu Q, Liu J, et al. Iron atom-cluster interactions increase activity and improve durability in Fe–N–C fuel cells. Nat Commun, 2022, 13(1): 2963.

[38] Lin R, Lim TM, Tran T Enhancement of mass transfer coefficient towards carbon nanotube nanoelectrode array. Sens Actuat B Chem, 2018, 260: 1052-1058.

[39] Ge L, Lin R, Zhu Z, et al. A nitrogen-doped electrocatalyst from metal-organic framework-carbon nanotube composite. J Mater Res, 2018, 33(5): 538-545.

[40] Yan W, Wu Y, Chen Y, et al. Facile preparation of N-doped corncob-derived carbon nanofiber efficiently encapsulating Fe₂O₃ nanocrystals towards high ORR electrocatalytic activity. J Energy Chem, 2020, 44: 121-130.

[41] Guo J, Li B, Zhang Q, et al. Highly accessible atomically dispersed Fe-N _x sites electrocatalyst for proton-exchange membrane fuel cell. Adv Sci, 2021, 8(5): 2002249.

[42] Cheng Y, Zhou S, Wang R, et al. A superior unitary oxygen electrode with accelerated mass transfer and highly exposed active sites for rechargeable air-based batteries. J Power Sour, 2021, 488.

[43] Huang H, Yu D, Hu F, et al. Clusters induced electron redistribution to tune oxygen reduction activity of transition metal single-atom for metal-air batteries. Angew Chem Int Ed Engl, 2022, 61(12

[44] Sarkar S, Biswas A, Siddharthan EE, et al. Strategic modulation of target-specific isolated Fe, Co single-atom active sites for oxygen electrocatalysis impacting high power Zn-air battery. ACS Nano, 2022, 16(5): 7890-7903.

[45] Shu C, Tan Q, Deng C, et al. Hierarchically mesoporous carbon spheres coated with a single atomic Fe–N–C layer for balancing activity and mass transfer in fuel cells. Carbon Energy, 2022, 4(1): 1-11.

[46] Long J, Chen J, Chen C, et al. MOFs encapsulated nanorods derived CoNi@CN composites with open structure as highly efficient bifunctional catalysts for rechargeable Zn-air batteries. J Colloid Interface Sci, 2023, 629(Pt A): 73-82.

[47] Cui J, Leng Y, Xiang Z FeNi co-doped electrocatalyst synthesized via binary ligand strategy as a bifunctional catalyst for Zn-air flow battery. Chem Eng Sci, 2022, 247.