Confinement Phosphorization Strategy Unlocks FeP–N–C Catalysts for Highly Stable Zinc-Air Batteries

Abstract

Rechargeable zinc-air batteries (RZABs) are promising next-generation energy storage systems due to their high theoretical energy density. However, their practical application is hindered by the slow reaction kinetics of oxygen reduction/evolution (ORR/OER) at air cathodes. Herein, an innovative N-rich copolymer-confined phosphorization strategy for synthesizing FeP nanoparticles encapsulated in carbon matrix (FeP–NPC) has been developed. The methodology employs an iron-phytic acid/aniline/pyrrole ternary copolymer precursor, achieving atomic-level interfacial coupling between FeP nanocrystals and carbon substrate through precisely controlled phosphating thermodynamics. Electrochemical characterization reveals exceptional bifunctional activity with ORR onset potential of 1.04 V versus RHE (0.85 V half-wave potential) and OER overpotential of 1.66 V at 10 mA cm⁻² in 0.1 M KOH electrolyte, comparable to commercial Pt/C-RuO₂ benchmarks. The assembled RZAB demonstrates a peak power density of 185.0 mW cm⁻² with remarkable durability maintaining 53.5% round-trip efficiency over 530 h cycling. Advanced spectroscopic analysis and DFT calculations elucidate that the N-rich carbon matrix induces the formation of FeP–N–C active sites which facilitates d-band center downshifting of FeP via interfacial charge redistribution, thereby optimizing oxygen intermediate adsorption/desorption energetics. Furthermore, the conductive carbon network acts as an electron reservoir to facilitate charge transfer kinetics during bifunctional catalysis. This interface engineering strategy provides a paradigm for developing cost-effective transition metal phosphide catalysts, advancing the practical implementation of metal-air battery technologies in energy storage systems.

Keywords

iron phosphide / oxygen evolution reaction / oxygen reduction reaction / rechargeable zinc-air batteries

References

[1] X. Zhang, Y. Liu, H. Dai, et al., “Efficient Trifunctional Electrocatalysts With Iron Single Atoms Electronically Coupled With Adjacent Ruthenium Nanoclusters for Zinc-Air Battery-Powered Water Splitting,” Applied Catalysis B: Environment and Energy 368 (2025): 125127.

[2] W. Deng, Z. Song, M. Jing, T. Wu, W. Li, and G. Zou, “Highly Active Air Electrode Catalysts for Zn-Air Batteries: Catalytic Mechanism and Active Center From Obfuscation to Clearness,” Carbon Neutralization 3, no. 4 (2024): 501–532.

[3] L. Yang, C. Du, J. Tian, et al., “Fully Exposed Copper Single-Atom Sites on Mesoporous N/S-Codoped Graphene for Efficient Zinc-Air Battery,” Applied Catalysis B: Environment and Energy 355 (2024): 124190.

[4] F. Wang, L. Wang, B. Wang, et al., “Cognate Cobalt Core-Shell Structure Decorated Nitrogen-Doped Hollow Carbon Bowls Triggering Advanced Zinc-Air Battery,” Advanced Functional Materials 35 (2025): 2415326.

[5] S. Zhang, W. Zhang, Y. Su, et al., “Facile Synthesis of 3D N-Doped Honeycomb-Like Carbon Nanocages as High-Performance Supercapacitor Electrodes,” Applied Surface Science 515 (2020): 146056.

[6] Y. Liu, Z. Li, Y. Zeng, et al., “Host–Guest Engineering of Dual-Metal Nitrogen Carbides as Bifunctional Oxygen Electrocatalysts for Long-Cycle Rechargeable Zn-Air Battery,” ChemElectroChem 8 (2025): 682.

[7] J. Zhou, J. Hu, X. Zhou, et al., “High-Entropy Doping for High-Performance Zero-Cobalt High-Nickel Layered Cathode Materials,” Energy & Environmental Science 18 (2025): 347–353.

[8] N. Liu, Y. Li, W. Liu, et al., “Engineering Bipolar Doping in a Janus Dual-Atom Catalyst for Photo-Enhanced Rechargeable Zn-Air Battery,” Nano-Micro Letters 17 (2025): 203.

[9] S. Zhang, W. Zhang, Y. Su, et al., “Nitrogen-Doped Honeycomb-Like Carbon Nanocages as High-Performance Electrodes for Supercapacitors,” Journal of Materials Chemistry A 8 (2020): 15621–15629.

[10] L. Chen, X. Wang, T. Lu, et al., “Maneuver of the D-Orbital Spin Polarization of Fe Single Atomic Sites via a Near-Range Axial Ligand Effect for Boosting Oxygen Reduction Reaction,” Applied Catalysis B: Environment and Energy 366 (2025): 125007.

[11] U. Y. Lee, D. I. Jeong, J. S. Ha, et al., “Fine-Tunable N-Doping in Carbon-Coated Cofe Nano-Cubes for Efficient Hydrogen Evolution in Aem Water Electrolysis,” Advanced Composites and Hybrid Materials 8 (2025): 140.

[12] Q. P. Ngo, T. T. Nguyen, M. Singh, R. Balaji, N. H. Kim, and J. H. Lee, “Vanadium Tunning Amorphous Iron Phosphate Encapsulated Iron Phosphide on Phosphorous-Doped Graphene Promoted Oxygen Reactions for Flexible Zinc Air Batteries,” Applied Catalysis, B: Environmental 331 (2023): 122674.

[13] Q. Zhou, M. Min, M. Song, et al., “In Situ Construction of Zinc-Mediated Fe, N-Codoped Hollow Carbon Nanocages With Boosted Oxygen Reduction for Zn–Air Batteries,” Small 19 (2023): 2307943.

[14] Y. Du, W. Chen, Z. Zhong, et al., “A High-Performance Electrocatalyst for Oxygen Reduction Derived From Copolymer-Anchored Polyoxometalates,” Nano Research 17 (2024): 5197–5205.

[15] Z. Xiao, C. Wu, W. Wang, et al., “Tailoring the Hetero-Structure of Iron Oxides in the Framework of Nitrogen Doped Carbon for the Oxygen Reduction Reaction and Zinc–Air Batteries,” Journal of Materials Chemistry A 8 (2020): 25791–25804.

[16] T. Chen, J. Wu, C. Zhu, et al., “Rational Design of Iron Single Atom Anchored on Nitrogen Doped Carbon as a High-Performance Electrocatalyst for All-Solid-State Flexible Zinc-Air Batteries,” Chemical Science 405 (2020): 125956.

[17] Y. Du, W. Chen, Z. Zhong, et al., ““Bifunctional Oxygen Electrocatalysts With Wn@Ni Nanostructures Implanted on N-Doped Carbon Nanorods for Rechargeable Zn-Air Batteries,” Journal of Alloys and Compounds 960 (2023): 170789.

[18] Z. Wang, X. Huang, T. Wang, R. Zhao, V. Chan, and G. Hu, “Vacancy Engineering of Fep Dispersed N,P-Doped Porous Carbon for High-Performance Capacitive Deionization,” Chemical Engineering Journal 484 (2024): 149666.

[19] Z. Fan, B. Pang, W. Chen, et al., “Synergistic Modulation of Iron Phosphide and Phosphorus-Doped Carbon to Boost Ammonia Electrosynthesis From Nitrate,” Chemical Engineering Journal 507 (2025): 160088.

[20] H. Seong, K. Min, G. Lee, K. Kwon, and S. H. Baeck, “Development of An Efficient Bifunctional Electrocatalyst Based on Co/CoSe₂ Nanoparticles Embedded in N, Se Co-Doped Carbon for AEMFC and Rechargeable Zn-Air Battery,” Applied Catalysis B: Environment and Energy 362 (2025): 124725.

[21] H. Liu, L. Jiang, Y. Liu, et al., “Construction of Single-Atomic Fe and Cu Sites Within Nitrogen/Sulfur Co-Doped Carbon Matrix for Boosting the Performance of Zinc-Air Batteries,” Applied Catalysis B: Environment and Energy 362 (2025): 124705.

[22] Y. He, Y. Cui, Y. Chen, and P. Tan, “Redox Mediators Optimize Reaction Pathways of Rechargeable Zn-Air Batteries,” Innovation Energy 1 (2024): 100028.

[23] Y. Xie, Y. Feng, S. Zhu, et al., “Modulation in Spin State of Co₃O₄ Decorated Fe Single Atom Enables a Superior Rechargeable Zinc-Air Battery Performance,” Advanced Materials 37 (2024): 2414801.

[24] F. Gui, Q. Jin, D. Xiao, et al., “High-Performance Zinc-Air Batteries Based on Bifunctional Hierarchically Porous Nitrogen-Doped Carbon,” Small 17 (2021): 210592.

[25] Y. Liu, Z. Li, S. Wang, et al., “Hierarchical Porous Yolk-Shell Co-N-C Nanocatalysts Encaged in Graphene Nanopockets for High-Performance Zn-Air Battery,” Nano Research 16 (2023): 8893–8901.

[26] S. Zhang, W. Zhang, Y. Su, et al., “3D N-Doped Honeycomb-Like Carbon Nanocages as Monolithic Electrodes for High-Performance Supercapacitors,” Applied Surface Science 534 (2020): 147578.

[27] J.-S. J. Friedrichs, L. Schmermund, C. Urmann, et al., “Synthesis of N-Substituted Pyrrole-2,5-Dicarboxylic Acids From Pyrroles,” Helvetica Chimica Acta 107 (2024): e202400036.

[28] D. Xue, S. Zhao, B. Lu, et al., “Disentangling the Activity-Stability Trade-Off of Pyrrolic N-Coordinated Fe-N₄ Catalytic Sites for Long-Life Oxygen Reduction Reaction in Acidic Medium,” Advanced Energy Materials 14 (2023): 2303733.

[29] W. Wang, F. Zhu, Y. Dai, H. Zhang, and J. Lei, “Electrosynthesis and Performance of Poly(Aniline/Pyrrole) Copolymer,” International Journal of Electrochemical Science 11 (2016): 4000–4006.

[30] L. Yu, D. Deng, X. Bao, et al., “Chain Mail for Catalysts,” Angewandte Chemie International Edition 59, no. 36 (2020): 15294–15297.

[31] Y. Guo, Y. Xue, Z. Zhou, et al., “Revolutionizing Zn-Air Batteries With Chainmail Catalysts: Ultrathin Carbon-Encapsulated Feni Alloys on N-Doped Graphene for Enhanced Oxygen Electrocatalysis,” Chinese Journal of Catalysis 58 (2024): 206–215.

[32] M. Perumalsamy, Y. Yoon, V. Elumalai, et al., “Engineering Spin State Modulation Through Phosphorus-Coordinated Fe-Nc Catalysts for Enhanced ORR Performance in Flexible Al-Air Batteries,” Applied Catalysis B: Environment and Energy 372 (2025): 125329.

[33] C. Cao, H. Hu, J. Duan, et al., “Phytic Acid Mediated N, P Co-Doped Hierarchical Porous Carbon With Boosting Capacitive Storage for Dual Carbon Lithium-Ion Capacitor,” Electrochimica Acta 470 (2023): 143310.

[34] Y. Su, H. Du, J. Xu, et al., “FeP Nanoparticles Anchored on N-Doped Carbon as ORR/OER Bifunctional Catalyst and Its Application in Zn-Air Batteries,” Fuel 387 (2025): 134349.

[35] Q. Lv, N. Wang, W. Si, et al., “Pyridinic Nitrogen Exclusively Doped Carbon Materials as Efficient Oxygen Reduction Electrocatalysts for Zn-Air Batteries,” Applied Catalysis, B: Environmental 261 (2020): 118234.

[36] W. Li, Y. Wu, M. Chen, et al., “Ultrathin Nitrogen-Doped Defective Carbon Layer Embedded With Nife for Solid Zinc-Air Batteries,” Journal of Alloys and Compounds 897 (2022): 166658.

[37] H. Huang, Q. Liang, H. Guo, et al., “Spray Pyrolysis Regulated Feco Alloy Anchoring on Nitrogen-Doped Carbon Hollow Spheres Boost the Performance of Zinc-Air Batteries,” Small 20 (2024): 2310318.

[38] Y. Pan, J. Gao, Y. Li, et al., “Constructing Nitrogen-Doped Carbon Hierarchy Structure Derived From Metal-Organic Framework as High-Performance ORR Cathode Material for Zn-Air Battery,” Small 19 (2023): 2304594.

[39] L. Ji, L. Li, X. Ji, et al., “Highly Selective Electrochemical Reduction of CO₂ to Alcohols on an FeP Nanoarray,” Angewandte Chemie International Edition 59, no. 2 (2020): 758–762.

[40] H. Tan, Y. Li, J. Kim, et al., “Sub-50 nm Iron–Nitrogen-Doped Hollow Carbon Sphere-Encapsulated Iron Carbide Nanoparticles as Efficient Oxygen Reduction Catalysts,” Advanced Science 5 (2018): 1800120.

[41] X. Jia, C. Du, J. Qin, et al., “Chemically Bubbled 3D N-Doped Honeycomb-Like Carbon Nanocage@Carbon Nanotube-Based Monolithic Electrode for Supercapacitor and Lithium Ion Battery,” Applied Surface Science 612 (2023): 155878.

[42] M. Manikanta Kumar and C. R. Raj, “Heteroatom-Doped Carbon-Encapsulated FeP Nanostructure: A Multifunctional Electrocatalyst for Zinc–Air Battery and Water Electrolyzer,” ACS Applied Materials & Interfaces 14 (2022): 15176–15186.

[43] X. Hu, Y. Min, L. Ma, et al., “Iron-Nitrogen Doped Carbon With Exclusive Presence of Fe_xn Active Sites as an Efficient ORR Electrocatalyst for Zn-Air Battery,” Applied Catalysis, B: Environmental 268 (2019): 118405.

[44] X. Li, Y. Yu, H. Xia, et al., “Atomically Dispersed Fe-N₄ Sites Anchored on Hierarchical Porous Carbon for High-Performance Oxygen Reduction Reaction in Acidic Medium,” Journal of Materials Chemistry A 9 (2021): 1168–1176.

[45] B. Chen, M. Zhou, N. Zhang, X. Deng, and H. Yang, “NH₃ Plasma-Etching-Derived Porous N-Doped Carbon Nanotubes With Fep Nanoparticles and Intrinsic Carbon Defects for Boosting Oxygen Reduction in Rechargeable Zn–Air Batteries,” Inorganic Chemistry Frontiers 11 (2024): 2690–2701.

[46] X. Shu, X. Cao, B. He, et al., “Coupling of Indium Clusters With Atomic Fe-N₄ on Carbon for Long-Term Rechargeable Zn–Air Batteries,” Energy & Environmental Science 18 (2025): 1262–1271.

[47] L. Zhang, D. H. Wu, M. U. Haq, J. J. Feng, F. Yang, and A. J. Wang, “Coordination Engineering and Electronic Structure Modulation of FeNi Dual-Single-Atoms Encapsulated in N, P-Codoped 3D Hierarchically Porous Carbon Electrocatalyst for Synergistically Boosting Oxygen Reduction Reaction,” Applied Catalysis B: Environment and Energy 351 (2024): 123991.

[48] G. Yang, H. Cai, Z. Xu, et al., “Spin Polarization Regulation of Fe–N₄ by Fe₃ Atomic Clusters for Highly Active Oxygen Reduction Reaction,” Science Bulletin 1 (2025): 2095–9273.

[49] L. Meng, S. Niu, Z. Wei, X. Qin, F. Naseem, and W. Wei, “Accelerated Proton-Coupled Electron Transfer Kinetics of Iron Phthalocyanine for Oxygen Reduction via Heteropoly Blue Clusters,” Applied Catalysis B: Environment and Energy 367 (2025): 125080.

[50] N. Wang, C. Meng, B. Wang, et al., “Spin-Regulated Fe-N-C Catalyst Enabled by Adjusting Coordination Nitrogen Species for Robust Oxygen Reduction,” National Science Review nwaf061 1 (2025): 2095–5138.

[51] Y. Liu, Z. Zhao, W. Wei, et al., “Single-Atom Fe-N4on a Carbon Substrate for Nitrogen Reduction Reaction,” ACS Applied Nano Materials 4 (2021): 13001–13009.

[52] L. Yan, R. Sun, S. Mahmood, et al., “Facilitating Reactant Accessibility to Heterometallic Phosphide With Superhydrophilic Interfaces for Efficient Electrochemical Production of Ammonia and Lactic Acid,” Applied Catalysis B: Environment and Energy 358 (2024): 124390.

[53] Z. Li, Y. Zeng, D. Xiong, et al., “Interfacial Engineering of Cobalt Phosphide Heterostructures Confined in N, P-Doped Carbon for Efficient Bifunctional Electrocatalysis in Zn-Air Batteries,” Inorganic Chemistry Frontiers 11 (2024): 549–561.

[54] Q. Luo, P. Zheng, L. Han, et al., “Recent Progress and Prospects of Manganese–Nitrogen–Carbon Electrocatalysts for Oxygen Reduction Reaction,” Applied Surface Science 682 (2025): 161629.

[55] Y. Du, Z. Zhong, L. Zhou, et al., “Coordination Polymer Derived Transition Metal Phosphide/Carbon Composites for Bifunctional Oxygen Electrocatalyst,” Journal of Materials Science & Technology 222 (2025): 142–151.

[56] X. Wang, J. Zhou, W. Cui, et al., “Electron Manipulation and Surface Reconstruction of Bimetallic Iron–Nickel Phosphide Nanotubes for Enhanced Alkaline Water Electrolysis,” Advanced Science 11, no. 26 (2024): 2401207.

[57] X. Li, G. Ye, W. Zhu, et al., “Directional Construction of Low-Coordination Fe–N3Coupled With Intrinsic Carbon Defects for High-Efficiency Oxygen Reduction,” ACS Nano 18, no. 35 (2024): 24505–24514.

[58] Y. Qiu, L. Fan, M. Wang, et al., “Precise Synthesis of Fe-N₂ Sites With High Activity and Stability for Long-Life Lithium–Sulfur Batteries,” ACS Nano 14, no. 11 (2020): 16105–16113.

[59] T. Liu, Y. Wang, and Y. Li, “How pH Affects the Oxygen Reduction Reactivity of Fe–N–C Materials,” ACS Catalysis 13, no. 3 (2023): 1717–1725.

[60] Y. Liu, L. Zong, Y. Zhang, F. Lu, and L. Wang, “Joule Heating Synthesis for Single-Atomic Fe Sites on Porous Carbon Spheres and Armchair-Type Edge Defect Engineering Dominated Oxygen Reduction Reaction Performance,” Applied Catalysis B: Environment and Energy 361 (2025): 124673.

[61] X. Xie, H. Peng, K. Sun, et al., “Rational Construction of FeNi₃/N Doped Carbon Nanotubes for High-Performance and Reversible Oxygen Catalysis Reaction for Rechargeable Zn-Air Battery,” Chemical Engineering Journal 452 (2023): 139253.

[62] S. Q. Deng, Z. Zhuang, C.-A. Zhou, et al., “Metal-Organic Framework Derived Feni Alloy Nanoparticles Embedded in N-Doped Porous Carbon as High-Performance Bifunctional Air-Cathode Catalysts for Rechargeable Zinc-Air Battery,” Journal of Colloid and Interface Science 641 (2023): 265–276.

[63] L.-C. Meng, H. Zhang, L. Kang, et al., “Robust and Flexible 3D Integrated Feni@NHCFs Air Electrode for High-Performance Rechargeable Zinc-Air Battery,” Rare Metals 1 (2024): 1–13.

[64] M. Qiao, Y. Wang, T. Wågberg, et al., “Ni-Co Bimetallic Coordination Effect for Long Lifetime Rechargeable Zn–Air Battery,” Journal of Energy Chemistry 47 (2020): 146–154.

[65] S. Huang, W. Zhang, Q. Chen, et al., “N-Doped Carbon Confined NiCo Alloy Hollow Spheres as An Efficient and Durable Oxygen Electrocatalyst for Zinc-Air Batteries,” Chemistry – A European Journal 29, no. 30 (2023): e202300321.

[66] R. Kumar, S. Kumar, S. G. Chandrappa, et al., “Nitrogen-Doped Carbon Nanostructures Embedded With Fe-Co-Cr Alloy Based Nanoparticles as Robust Electrocatalysts for Zn-Air Batteries,” Journal of Alloys and Compounds 984 (2024): 173862.

[67] R. Wu, X. Wang, L. Ge, et al., “N, S Co-Doped Carbon With Embedment of Feni Alloy as Bifunctional Oxygen Electrocatalysts for Rechargeable Zinc-Air Batteries,” Carbon 202 (2023): 141–149.

[68] G. Fang, J. Gao, J. Lv, et al., “Multi-Component Nanoporous Alloy/(Oxy) Hydroxide for Bifunctional Oxygen Electrocatalysis and Rechargeable Zn-Air Batteries,” Applied Catalysis B: Environment and Energy 268 (2020): 118431.

[69] S. Liu, C. Li, M. J. Zachman, et al., “Atomically Dispersed Iron Sites With a Nitrogen–Carbon Coating as Highly Active and Durable Oxygen Reduction Catalysts for Fuel Cells,” Nature Energy 7 (2022): 652–663.

[70] Y. Liu, J. Wang, Q. Shi, et al., “A Stress Self-Adaptive Structure to Suppress the Chemo-Mechanical Degradation for High Rate and Ultralong Cycle Life Sodium Ion Batteries,” Angewandte Chemie International Edition 62, no. 29 (2023): e202303875.

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