FePc Molecules Research Articles

Hierarchical pore engineering of MOF-5 derived electrocatalysts with high mass transfer for zinc-air flow batteries

From micro to macro level, the performance of zinc-air flow battery (ZAFB) hinges on two crucial factors: the effective oxygen reduction reaction (ORR) electrocatalysts, and the durable triple-phase electrodes. However, sluggish kinetic process always occurs due to insufficient active sites and hysteretic mass transfer. In this work, a well-confined iron phthalocyanine (FePc) structure onto carbonized metal-organic framework (C-MOF5) electrocatalyst is constructed through a pyrolysis-free strategy. The macrocyclic skeleton of MOF-5 has been confirmed to offer a stronger and more abundant environment for hosting FePc molecules. Attributing to the hierarchical pore engineering of MOF-5, the FePc@C-MOF5 electrocatalyst reveals a high content of Fe (5.68 wt%) with multiple exposed active sites. Notably, the FePc@C-MOF5 exhibits a remarkably high half-wave potential of 0.915 V for ORR in 0.1 M KOH, surpassing that of commercial Pt/C by nearly 60 mV. From a higher-level device perspective, the highest oxygen diffusion velocity and local current density of the FePc@C-MOF5 electrode is verified by computational fluid dynamics (CFD) simulations. As a result, the as-assembled ZAFB demonstrates long-term stability with 200 h’ cycling. This work not only presents the hierarchical pore tailoring strategy for designing ORR electrocatalysts but also offers a deeper understanding of the essence of interfacial mass transfer.

Single-atom Fe catalysts with pyrrolic-type FeN4 sites for efficient oxygen reduction reaction: Identifying the roles of different N species

Developing electrocatalysts with efficient cathode oxygen reduction reaction (ORR), for example, iron-based single-atom catalysts (Fe-SACs), has been deemed necessary to accelerate the commercialisation process of zinc (Zn)–air batteries. Nevertheless, determining how various nitrogen species and active metal centres coordinate on an atomic scale remains unclear and inadequately explained. Herein, we demonstrate a soft-template-aided technique using Fe-containing molecules (e.g. iron phthalocyanine [FePc], Fe-1,10-phenanthroline [Fe-Phen] and Fe-glucose) to enhance the performance of Fe-SACs in terms of ORR. In this technique, FePc molecules can be converted into atomically dispersed pyrrolic-type iron–nitrogen (FeN4) sites during a pyrolytic process. The resultant catalyst exhibits excellent ORR activity (half-wave potential = 0.90 V) in alkaline medium and standing battery performance when used in Zn–air batteries (peak power density = 197.3 mW cm−2 and specific capacity = 796.2 mAh g−1). As per the findings from control experiments and characterisation studies, electron transfer between the support and the active Fe centre amplifies the ORR performance. Theoretical calculations substantiate that Fe sites coordinated with pyrrolic N atoms govern the electronic configuration of the catalysis, reducing the free energy absorption of reaction intermediates and thus increasing its intrinsic ORR capability. Herein, we aim to offer a fresh perspective on the relation between coordination environments and catalytic activity in ORR catalysts.

Spin filtering, magnetoresistance and seebeck effects in phthalocyanine based molecular junctions between phosphorus nanoribbon electrodes

This research utilized the non-equilibrium Green’s function (NEGF) method combined with density functional theory (DFT) to explore spin transport in binuclear transition metal phthalocyanine (TMPc) molecules between black phosphorus nanoribbon electrodes. The device achieves near 100% SFE with ferromagnetic coupling of Manganese phthalocyanine (MnPc) and Iron phthalocyanine (FePc). When the MnPc and FePc molecules exhibited anti-ferromagnetic coupling, with the transports in the two spin channels significantly smaller than in the ferromagnetic coupling scenario, demonstrating giant magnetoresistance effects. MnPc shows high Seebeck polarization at 149 K, while FePc maintains it at a low temperature. This research opens new avenues for designing molecular spintronic devices with two-dimensional electrodes.

Unconventional Surface Doping Effect on the Spin State of an Adsorbed Magnetic Molecule.

Magnetic molecules adsorbed on two-dimensional (2D) substrates have attracted broad attention because of their potential applications in quantum device applications. Experimental observations have demonstrated substantial alteration in the spin excitation energy of iron phthalocyanine (FePc) molecules when adsorbed on nitrogen-doped graphene substrates. However, the underlying mechanism responsible for this notable change remains unclear. To shed light on this, we employ an embedding method and ab initio quantum chemistry calculations to investigate the effects of surface doping on molecular properties. Our study unveils an unconventional chemical bonding at the interface between the FePc molecule and the N-doped graphene. This bonding interaction, stronger than non-covalent interactions, significantly modifies the magnetic anisotropy energy of the adsorbed molecule, consistent with experimental observations. These findings provide valuable insights into the electronic and magnetic properties of molecules on 2D substrates, offering a promising pathway for precise manipulation of molecular spin states.

Intrinsic Defect‐Rich Carbon‐Supported Iron Phthalocyanine as Beyond‐Pt Oxygen Reduction Catalysts for Zinc–Air Batteries

Molecular iron phthalocyanine (FePc) bearing a single‐atom Fe–N4 moiety is a high‐profile non‐platinum catalyst toward the oxygen reduction reaction (ORR), but its unsatisfactory activity and inadequate stability hinder the practical application. Herein, a novel strategy by hybridizing FePc with fullerene‐derived intrinsic defect‐rich carbon to improve its ORR activity and stability is reported. Via alkali‐assisted thermal pyrolysis, C60 molecules are disintegrated into tiny fragments that then restructure into pentagon‐ and edge‐rich carbon (FC). Utilizing FC as a support of FePc leads to a significantly improved ORR activity compared to other supports including reduced graphene oxide and carbon nanotube that hold distinct structural features. The optimized FePc/FC with a Fe loading of 3 wt% presents a half‐wave potential of 0.917 V, far beyond that of Pt/C (0.846 V), via selective four‐electron ORR pathway and excellent stability under accelerated stress test. The practical applicability of FePc/FC is also demonstrated as a high‐performing cathode catalyst of aqueous zinc–air batteries. It is, for the first time, explicitly disclosed that strong interactions between FePc molecules and intrinsic carbon defects (e.g., pentagons and edges) not only strengthen the anchoring effect of supported FePc but also enhance the intrinsic ORR activity of single‐atom Fe–N4 sites.

The role of nitrogen sources and hydrogen adsorption on the dynamic stability of Fe-N-C catalysts in oxygen reduction reaction.

Fe-N-C catalysts are promising alternatives to Pt-based electrocatalysts for the oxygen reduction reaction (ORR) in various electrochemical applications. However, their practical implementation is impeded by their instability during prolonged operation. Various degradation mechanisms have been proposed, yet the real origin of the intrinsic instability of Fe-N-C structures under ORR operations is still disputed. Herein, we observed a new type of protonation mechanism based on advanced first-principles simulations and experimental characterizations. The results revealed strong evidence of pyrrolic-N protonation in pyrrolic-type FeN4, which plays a vital role for the low kinetic barrier of Fe leaching. Conversely, the pyridinic-type FeN4 prefers protonation at the Fe site, contributing to the higher barrier of Fe leaching and relatively higher stability. The facile pyrrolic-N protonation is verified by various spectroscopy characterizations in the Nafion-treated FePc molecule. Crucially, the presence of oxygen-containing intermediates at the Fe site can further work synergistically with N protonation to promote conversion of iron atoms (Fe-N4) into ferric oxide under working potentials, and the more positive the electrode potential, the lower the kinetic barrier of Fe leaching. These findings serve as a foundation for future research endeavors on the stability issues of Fe-N-C catalysts and advancing their application in sustainable energy conversion technologies.

Effect of annealing on the molecular ordering and crystal structure of iron phthalocyanine thin films on Si (111) surface

The Effect of annealing on molecular ordering in Iron Phthalocyanine (FePc) thin films deposited on Si (111) substrate surface was investigated using lab source (Cu Kα) based x-ray diffraction, synchrotron based 2-dimensional grazing incidence x-ray diffraction, polarization dependent x-ray absorption spectroscopy and hard x-ray photoelectron spectroscopy. Room temperature deposition of FePc on Si substrate resulted in amorphous thin films with randomly oriented FePc molecules. However, annealing of these amorphous films at 200°C led to crystallization with highly ordered FePc molecules having monoclinic crystal lattice structure. The ordered FePc molecules followed edge-on stacking on Si substrate surface with an azimuthally averaged tilt angle of 75±5° between molecular plane and substrate surface. Also, the b-c plane of the unit cell was lying almost parallel to the substrate surface. The edge-on stacking ordering of FePc molecules in annealed thin films led to higher charge conduction as compared to as-deposited films.

Molecular catalysts with electronic axial stretching for high-performance lean-oxygen seawater batteries

A dissolved-oxygen seawater battery (SWB) can generate electricity by reducing dissolved oxygen and sacrificing the metal anode at different depths and temperatures in the ocean, acting as the basic unit of spatially underwater energy networks for future maritime exploration. However, most traditional oxygen reduction reaction (ORR) catalysts are out of work at such ultralow dissolved oxygen concentration. Here, we proposed that the electronic axial stretching of the catalyst is essentially responsible for enhancing the catalyst’s sensitivity to dissolved oxygen. By modulating the lattice of iron phthalocyanine (FePc) as a model catalyst, the unique electronic axial stretching in the z-direction of planar FePc molecules was realized to achieve a boosted adsorption and electron transfer and result in a much improved ORR activity in lean-oxygen seawater environment. The peak power density of a homemade SWB using a practical carbon brush electrode decorated by the FePc is estimated to be as high as 3 W L−1. These results provide inspiring insights into the interaction between the catalyst and complicated seawater environment, and propose the electronic axial stretching as an effective indicator for the rational design of catalysts to be used in extremely lean-oxygen environment.

Soft ferromagnetic effect in FePc/CdS hybrid diluted magnetic organic/inorganic quantum dots

Manipulating magnetic interactions in diluted magnetic quantum dots (DMQDs) is a fundamental research field due to the potential for developing robust magnetic semiconducting materials that can operate effectively in various environmental conditions. Here we design a new class of DMQDs via hybridization of inorganic CdS QDs with organic iron phthalocyanine (FePc) molecules. By a combination of X-ray photoemission, Mӧssbauer spectroscopies, and vibrating sample magnetometry, we demonstrate that FePc molecules alter the original diamagnetic nature of CdS QDs. They turn them into room-temperature soft-ferromagnets, while preserving the CdS QD structure from further oxidation in a more efficient way than the standard Fe doping of CdS QDs. These hybrid materials open up new possibilities for the design of DMQDs of tunable and robust magnetism for optomagnetic and spintronic applications.

Surface engineering of Pt aerogels by metal phthalocyanine to enhance the electrocatalytic property for oxygen reduction reaction

Noble metal aerogels (NMAs) have been widely investigated as electrocatalysts for sustainable energy conversion, while enhancing the catalytic activity and stability of NMAs is conducive to reduce cost and expand their application. Herein, modifying Pt aerogel by metal phthalocyanine (MPc) molecules (Pt aer-MPc) was proposed to improve the oxygen reduction reaction (ORR) performance. Typically, the Pt aer-FePc showed significant improvement in half-wave potential, mass, and specific activity compared to commercial Pt/C. Theoretical calculations revealed that the synergy between FePc molecules and Pt aerogel constructs a new interface to facilitate the reduction of oxygen and weaken the bind energies of oxygen intermediates, thus leading to improved ORR performance. Similar promotion in ORR catalytic property was also observed for Pt nanoparticles and commercial Pt/C with the modification of FePc. Therefore, this work not only provides a universal engineering method of MPc decoration to enhance ORR performance of Pt-based electrocatalysts, but also opens a new pathway for designing advanced ORR electrocatalysts with functional molecules toward critical energy-related applications.

Highly dispersed ultrasmall iron phthalocyanine molecule clusters confined by mesopore-rich N-doped hollow carbon nanospheres for efficient oxygen reduction reaction and Zn-air battery

Iron phthalocyanine (FePc) has attracted extensive attention due to its unique planar symmetric Fe-N4 sites, which are considered to be the ideal active sites for oxygen reduction reaction (ORR) catalysis. However, the electrocatalytic performance of FePc is still unsatisfactory due to its low intrinsic activity, inadequate exposure and low utilization rate of Fe-N4 active sites. Herein, we synthesize a novel hybrid catalyst (FePc-NHCS-500) by coupling dispersed FePc molecule clusters into the defect-rich nitrogen-doped hollow porous carbon spheres (NHCS). Benefiting from the confining effect of mesopores in the NHCS, the well dispersed ultrasmall FePc molecule clusters exhibit excellent ORR performance with Tafel slope of 41 mV dec−1, half-wave potential (E1/2) of 0.94 V and kinetic current density (Jk) of 25.39 mA cm−2 at 0.9 V. Moreover, the as-assembled Zn-air battery (ZAB) using the FePc-NHCS-500 electrocatalyst as air electrode exhibits excellent performance, with open circuit voltage (OCV) of 1.524 V, peak-power density of 230 mW cm−2 and specific capacity of 808.7 mAh g−1. This work not only designs a non-noble metal catalyst with excellent ORR performance, but also makes reasonable guidance for the practical application of the catalyst in renewable energy storage and conversion.

MOF-derived N-doped carbon nanosticks coupled with Fe phthalocyanines for efficient oxygen reduction

The rational design and preparation of atomic-level dispersed non-platinum catalysts to achieve efficient oxygen reduction reactions (ORR) is worth exploring for clean energy conversion and storage technology. Herein a simple self-templating strategy is demonstrated to obtain MIL-68-NH2-x series using pyridine as a surfactant to realize micron-scale to nanosized conversion. Among them, the as-prepared MIL-68-NH2-300 owns a large specific surface area and abundant pore defects after thermal treatment, which can effectively adsorb and anchor Fe phthalocyanines (FePc). In this case, MOF-derived N-doped carbon nanosticks coupled with FePc molecules (FePc@NCNS) exhibit an excellent electrocatalytic ORR activity with a positive half-wave potential (0.904 V), a large diffusion-limited current density (6.17 mA cm−2) and a high current retention after 20 h (95.7%). Furthermore, the high performance of ORR is confirmed by the relevant theoretical calculations on O2 adsorption ability. These above results will pave the way for MOF-derived carbon nanomaterials with specific morphological dimensions for high-performance energy conversion and storage.

Effects of monolayer and bilayer silica films on Fe-Phthalocyanine adsorption properties

We explore the adsorption properties of Fe-Phthalocyanine (FePc) molecule at various configurations of silica films supported by Ru(0001) and report on the geometric, electronic and magnetic features of the energetically preferred structures to fully understand the influence of the silica films on the adsorption properties of the FePc molecule. The investigation is carried out with the use of density of functional theory calculations and the self-consistent inclusion of van der Waals interaction. In addition, Oxygen atoms are added to govern the atomic structure of the silica overlayers on the surface. Our results show that both FePc/silica thin film systems exhibit both physisorption and chemisorption simultaneously. In addition, the FePc molecule on each substrate undergoes a symmetry reduction driven by mismatch with the substrates' symmetry as well as the breakup of the degenerate orbitals of Fe.

Surface bonding of MN4 macrocyclic metal complexes with pyridine-functionalized multi-walled carbon nanotubes for non-aqueous Li-O2 batteries

It is essential to develop bifunctional catalysts with high activity and stability for reversible oxygen reduction reactions (ORRs) and oxygen evolution reactions (OERs) in lithium-oxygen (Li-O2) batteries. In this work, pyridine (Py) functionalized multi-walled carbon nanotubes (MWCNTs) were prepared to immobilize various solid MN4 macrocyclic metal complexes (MN4-MC) as cathode electrocatalysts for Li-O2 batteries. Three types of MN4-MC molecules, including iron phthalocyanine (FePc), cobalt phthalocyanine (CoPc) and iron protoporphyrin IX (Heme) were examined to evaluate the influence of central metal atoms and ligand substituents found in MN4-MC molecules on the electrocatalytic performance of the study samples. The order of the ORR/OER catalytic activity of the bifunctional catalysts is FePc > Heme > CoPc. The central metal atom in FePc molecule has the highest occupied molecular orbital (HOMO) energy than the corresponding metal atoms in CoPc and Heme molecules. This made the molecule to have better dioxygen-binding ability and higher catalytic activity in the ORR process; it also made it to easily lose electrons that were oxidized in the OER process. This study proposed a simplified scheme of the electrode surface route to assist in understanding the diverse ORR/OER performances of MN4-MC. It is discovered that the positive core of the MN5 coordination sphere in MN4-MC/Py/MWCNTs composite is the primary active site that can influence the formation of MN5···O2* and MN5-LOOLi cluster in the ORR process. The interfacial electron could be easily delivered between MWCNTs and MN5 active site through the Py bridge. This facilitated the formation and decomposition of MN5-LOOLi species during the ORRs/OERs, leading to the enhancement of its catalytic performance. This work provides a new insight into the effects of the molecular structure and organization of MN4-MC on the catalytic activity of O2 electrodes in Li-O2 batteries.

Well-defined metal-N4 sites coordinated defective carbon as efficient electrocatalysts for high performance lithium–sulfur batteries

The practical application of lithium–sulfur batteries has been limited by the detrimental shuttling behavior and sluggish conversion kinetics of lithium polysulfides (LiPSs), especially under high sulfur loading and lean electrolyte dosage. Although experimental and theoretical studies show that introducing defect and Fe–N4 site in carbon materials is the desirable strategy to expedite LiPSs conversion, the synergetic effect between them for sulfur redox chemistry is hardly explored. Herein, derived from a well-define Fe–N4 macrocyclic pristine iron phthalocyanine molecules (FePc) coordinated on the defective carbon nanosheets (FePc-DC), the marriage and synergetic effect between defective carbon and FePc molecules can induce remarkable Fe center electron delocalization and regulate the local electron redistribution between FePc-DC interfaces, thus brings improved LiPSs adsorption ability and conversion reaction rate. Meanwhile, the robust two-dimensional flake texture with large surface area and abundant porosity ensures robust physical confinement and fast electron/ion transfer. Attributed to such unique features, the lithium–sulfur batteries with FePc-DC cathode delivers good electrochemical performance with high areal capacity of 5.53 mAh/cm2 under high sulfur mass loading of 4.9 mg/cm2 and low electrolyte/sulfur ratio of 6.5 μL/mg, demonstrating great potential in advanced Li–S batteries.

Enhanced electronic interaction between iron phthalocyanine and cobalt single atoms promoting oxygen reduction in alkaline and neutral aluminum-air batteries

Aluminum-air batteries (AABs) have received increasing interest for next-generation energy conversion systems. However, the development of AABs is hindered by the sluggish kinetics of cathodic oxygen reduction reaction (ORR). Iron phthalocyanine (FePc) is one of the active electrocatalysts for ORR but still far from Pt-based materials in terms of electrocatalytic performance. Herein, FePc molecules anchored on the Co single atoms/N-doped porous carbon nanofibers (denoted as FePc@Co-SAs/PCNF) with enhanced electronic interaction are prepared for the ORR. X-ray absorption spectra (XAS) analysis confirms the atomically dispersed Fe and Co sites and reveals the electronic interaction between FePc and Co-N3. The cobalt single atoms can break the electronic distribution symmetry of FePc and induce electronic localization to boost the ORR performance. As a result, the FePc@Co-SAs/PCNF electrocatalyst demonstrates a remarkable ORR activity in both alkaline and neutral electrolytes. The electrocatalytic ORR processes on the FePc@Co-SAs/PCNF are recorded by in-situ Raman spectra. Moreover, the ORR mechanism is discussed, which is supported by density functional theory (DFT) calculations. Furthermore, the AABs based on FePc@Co-SAs/PCNF exhibit remarkable discharge performance. This study offers a new strategy for rationally designing metallic macrocyclic compound electrocatalysts and promotes the development of metal-air batteries.

N/O‐co‐doped Carbon Shell Structures Loaded with Iron Phthalocyanine for Oxygen Reduction Catalysis

AbstractMetal phthalocyanines (MPcs) have highly conjugated π electron systems and metal atoms acting as active centers, and so exhibit excellent electrocatalytic performance during the oxygen reduction reaction (ORR). However, these complexes also tend to undergo aggregation and exhibit poor electrical conductivity and minimal durability, all of which hinder their large‐scale industrial applications. In the present study, iron phthalocyanine (FePc) is applied to hollow carbon shells (HCSs) to generate an ORR catalyst containing single Fe atoms(HCS‐O‐FePc). The HCSs have numerous N/O‐based surface functional groups that promote the formation of Fe−O bonds with the FePc held in an axial coordination position. These axial Fe−O bonds disrupt the electron symmetry in the plane of the FePc molecules, which facilitate electron transfer. 1100HCS‐O‐FePc exhibits an onset potential of 0.98 V (vs RHE), a half‐wave potential of 0.91 V (vs RHE), an electron transfer number of 3.90, and durability better than that of a 20 % commercial Pt/C catalyst. Electrochemical impedance spectroscopy demonstrates that the ORR process over this material likely proceeds via a rapid 2+2 electron mechanism. This composite displays excellent oxygen reduction properties and is a promising alternative to Pt‐based ORR catalysts.

Experimental and DFT studies of oxygen reduction reaction promoted by binary site Fe/Co–N–C catalyst in acid

• The Fe–Co bimetallic sites were confirmed in FeCo–N–C by one-step pyrolysis. • The as-prepared catalyst achieves high ORR performance in acidic electrolytes. • The bimetallic site can result in facile cleavage of the O–O bond and thus a direct 4e − ORR process. • The FeCoNC-10 exhibits remarkable performance in DMFCs with superior methanol tolerance. The cost and efficiency issues of cathodic electrocatalyst for oxygen reduction reaction (ORR) hinder a broad application of fuel cells. Therefore, it is necessary to develop highly efficient and sustainable ORR electrocatalysts of platinum group metal-free (PGM-free). The atomically dispersed FeCoNC-10 electrocatalysts were constructed by incorporating Fe phthalocyanine (FePc) molecules into bimetallic metal–organic frameworks (BMOF) followed by one-step pyrolysis. It showed remarkable ORR activity in acidic medium compared with FeNC and CoNC catalysts. The Fe–Co bimetallic sites were confirmed in FeCo–N–C, together with abundant isolated FeN 4 and CoN 4 sites. Theoretical study revealed that the bimetallic site can enhance O 2 adsorption and elongate O–O bond length rather than FeN 4 and CoN 4 . This can result in facile cleavage of the O–O bond and thus a direct 4e − ORR process. FeCoNC-10 catalyst showed enhanced ORR stability, due to very weak Fenton-type reaction related to Co species. Membrane electrode assemblies (MEAs) consisted of the FeCoNC-10 was applied in the cathode. It showed a peak power density of 100 mW cm −2 in a direct methanol fuel cells (DMFCs) with superior methanol tolerance. This work sheds light on the mechanism of atomically dispersed Fe/Co dual-doped carbon in enhancing ORR activity and stability, which enables the cost-effective ORR electrocatalyst design to achieve robust fuel cell performance.

P-functionalized carbon nanotubes promote highly stable electrocatalysts based on Fe-phthalocyanines for oxygen reduction: Experimental and computational studies

Iron(II) phthalocyanines (FePc) supported on functionalized nanostructured carbon materials have been studied as electrocatalysts for the oxygen reduction reaction (ORR) in an alkaline medium. Herein, two types of carbon nanotubes (CNTs) have been explored as support, Single-Walled Carbon Nanotubes and Herringbone Carbon Nanotubes (SWCNTs and hCNTs, respectively), both electrochemically modified with ortho- aminophenylphosphonic acid (2APPA), which provides phosphate axial coordinating ligands for the immobilization of FePc molecules. All the catalysts were prepared via a facile incipient wetness impregnation method. Comprehensive experimental analysis together with density functional theory (DFT) calculations has demonstrated both the importance of the five-coordinated Fe macrocycles that favor the interaction between the FePc and the carbon support, as well as the effect of the CNT structure in the ORR. FePc axial coordination provides a better dispersion, leading to higher stability and a favorable electron redistribution that also tunes the ORR performance by lowering the stability of the reaction intermediates. Interestingly, such improvement occurs with a very low content of metal (∼1 wt% Fe), which is especially remarkable when hCNT support is employed. This work provides a novel strategy for the development of Fe-containing complexes as precious metal-free catalysts towards the ORR.

Understanding electronic configurarions and coordination environment for enhanced ORR process and improved Zn-air battery performance

Electronic configurations and coordination environment of catalysts play the crucial roles for oxygen reduction reaction (ORR). However, most of current efforts have been focused on the geometry design and recognition of active sites, resulting in the rare studies on the intrinsic activity of reaction sites and the synergistic effects between metal centers and external environment. Herein, a dual performance optimization of iron phthalocyanine (FePc) molecules is realized via introducing reduced graphene oxide (rGO) as the carrier. Coupling of rGO and Fe-N4 moiety can further boost Fe 3d electron spin state transition and C 2p charge delocalization. The higher spin state of Fe ions and more Fe-N4 local charge accelerate the electron transfer between Fe sites and adsorbed reactants/intermediates, rendering in an enhanced ORR performance. Under alkaline conditions, the ORR activity (Tafel slope of 39.1 mV dec−1 and an onset potential of 0.98 V vs. RHE) and durability of optimal catalyst exceed commercial Pt/C and many reported Fe-N-C electrocatalysts. Both liquid and solid state Zn-air batteries driven by this catalyst also exhibit satisfactory practical application potential. This work provides a novel insight into the Fe 3d orbitals electronic structure and internal charge whereabouts of catalyst in oxygen electroreduction reactions.