Efficient Electrocatalyst For Oxygen Reduction Reaction Research Articles

Atomic-thin VN layer@N-doped carbon as efficient oxygen reduction reaction electrocatalysts

The defect engineering is of vital importance for electrocatalysts because it can provide an additional yet advanced tier to further boost catalysis, especially for ultrathin nanosheets of transitional metal compounds with a high surface to bulk ratio and more importantly the ability to engineer the defect along the longitudinal direction of the grain boundaries. Herein, we developed super-thin and ordered face-centered cubic VN nanosheets with grain boundaries using a new facile and in-situ method. The structural and morphological properties of the prepared samples were investigated, finding that the temperature has significant effects on the distribution of sheets. The thickness of nanosheets is only 1.3 nm the same as that of three cubic VN crystal unit cells, which is pivotal to the electrochemical reaction. The detailed electrocatalysts results show that the VN nanosheets (NSs) exhibit interesting ORR performance with the onset potential of 0.93 V and a half-wave potential of 0.86 V. The evenly distributed VN NSs display the highest durability with only 5% attenuation after 50000s operation for the oxygen reduction reaction. We provide a new strategy to synthesize super-thin nitrides nanosheet structure, highlighting the strong correlation between surface engineering and the performance of electrocatalysts for potential practical oxygen reactions.

Computational Screening of Two-Dimensional Metal-Organic Frameworks as Efficient Single-Atom Catalysts for Oxygen Reduction Reaction.

The development of efficient and inexpensive oxygen reduction reaction (ORR) catalysts is crucial for renewable energy technologies. Herein, using density functional theory (DFT) methods and microkinetic simulations, we systematically investigated the ORR catalytic performance of a series of 2D metal-organic frameworks M3 (HADQ)2 (HADQ=2,3,6,7,10,11-hexaamine dipyrazino quinoxaline). It shows that all 2D M3 (HADQ)2 (M=Cr, Mn, Fe, Co, Ni, Cu, Ru, Rh and Pd) monolayers are metallic, due to π-conjugated crystal orbitals centered on the central metals and ligand N atoms. The catalytic activity of M3 (HADQ)2 depends on the binding strength between ORR intermediates and metal species, and can be tuned via changing the central metals. Among these candidates, Rh3 (HADQ)2 and Co3 (HADQ)2 show superior ORR performance to Pt (111) with high half-wave potentials of 0.99 and 0.93 V, respectively. Moreover, the screened two catalysts have excellent intermediate-tolerance ability for dynamic coverage of oxygenated species on the active sites. Our work provides a new path towards developing efficient ORR electrocatalysts.

One-step synthesis of S, N dual-element doped rGO as an efficient electrocatalyst for ORR

The commercial application of oxygen reduction reaction (ORR) technology challenges the development of new electrocatalysts with excellent performance, high stability and low cost. Non-metallic materials, especially graphene-based catalysts, have become potential electrocatalysts for ORR due to their source richness and good stability. Here, we report a simple one-step hydrothermal method to synthesize S, N dual-element doped reduced graphene oxide (S, N-rGO) for ORR using graphene oxide as carbon source, thiourea as both sulfur-nitrogen source and reducing agent. The ORR performance is effectively enhanced by heteroatoms doping that increases the active sites of edge defects, introduces new S and N active sites, and adjusts the electronic structure of rGO. The 0.05-S, N-rGO catalyst shows the optimal ORR activity under alkaline conditions with the onset potential of 0.793 V vs RHE, good stability and anti-tolerance toward methanol. The calculated electron transfer number of about 3.1 ± 0.1 suggests that both the two-electron and four-electron processes occur on the catalyst.

Electrocatalytic Oxygen Reduction Reaction of Graphene Oxide and Metal-Free Graphene in an Alkaline Medium.

Graphene is a well-known two-dimensional material with a large surface area and is used for numerous applications in a variety of fields. Metal-free carbon materials such as graphene-based materials are widely used as an electrocatalyst for oxygen reduction reactions (ORRs). Recently, more attention has been paid to developing metal-free graphenes doped with heteroatoms such as N, S, and P as efficient electrocatalysts for ORR. In contrast, we found our prepared graphene from graphene oxide (GO) by the pyrolysis method under a nitrogen atmosphere at 900 °C has shown better ORR activity in aqueous 0.1 M potassium hydroxide solution electrolyte as compared with the electrocatalytic activity of pristine GO. At first, we prepared various graphene by pyrolysis of 50 mg and 100 mg of GO in one to three alumina boats and pyrolyzed the samples under a N2 atmosphere at 900 °C. The prepared samples are named G50-1B to 3B and G100-1B and G100-2B. The prepared GO and graphenes were also analyzed under various characterization techniques to confirm their morphology and structural integrity. The obtained results suggest that the ORR electrocatalytic activity of graphene may differ based on the pyrolysis conditions. We found that G100-1B (Eonset, E1/2, JL, and n values of 0.843, 0.774, 4.558, and 3.76) and G100-2B (Eonset, E1/2, and JL values of 0.837, 0.737, 4.544, and 3.41) displayed better electrocatalytic ORR activity, as did Pt/C electrode (Eonset, E1/2, and JL values of 0.965, 0.864, 5.222, and 3.71, respectively). These results display the wide use of the prepared graphene for ORR and also can be used for fuel cell and metal-air battery applications.

Spin-Selective Coupling in Mott-Schottky Er2 O3 -Co Boosts Electrocatalytic Oxygen Reduction.

Alkaline oxygen reduction reaction (ORR) is critical to electrochemical energy conversion technology, yet the rational breaking of thermodynamic inhibition for ORR through spin regulation remains a challenge. Herein, a Mott-Schottky catalyst consisting of Er2 O3 -Co particles uniformly implanted into carbon nanofibers (Er2 O3 -Co/CNF) is designed for enhancing ORR via spin-selective coupling. The optimized Er2 O3 -Co/CNF affords a high half-wave potential (0.835V vs reversible hydrogen electrode, RHE) and onset potential (0.989 VRHE ) for the ORR surpassing individual Co/CNF and Er2 O3 /CNF. Theoretical calculations reveal the introduction of Er2 O3 optimizes the electronic structure of Co through Er(4f)-O(2p)-Co(3d) gradient orbital coupling, resulting in significantly enhanced ORR performance. Through gradient orbital coupling, the induced spin-up hole in Co 3d states endows the Er-O-Co unit active site with a spin-selective coupling channel for electron transition. This favors the decrease of the energy gap in the potential-limiting step, thus achieving a high theoretical limiting potential of 0.77 VRHE for the Er2 O3 -Co. Moreover, the potential practicability of Er2 O3 -Co/CNF as an air-cathode is also demonstrated in Zn-air batteries. This work is believed to provide, new perspectives for the design of efficient ORR electrocatalysts by engineering spin-selective coupling induced by rare-earth oxides.

Engineering d-band center of FeN4 moieties for efficient oxygen reduction reaction electrocatalysts

Atomically-dispersed FeN4 moieties are emerging as low-cost electrocatalysts for oxygen reduction reaction (ORR), which can be applied in fuel cells and metal-air batteries. Whereas, the unsatisfactory position of the d-band center from the metal sites offered by FeN4 affects the adsorption-desorption behaviors of oxygenated intermediates, further impeding the improvement of their ORR performances. Herein, we report a well-designed diatomic Fe/Zn-CNHC catalyst on a microporous hollow support. This strategy drives the position of the d-band center of Fe upward, thus making FeN4 active sites more favorable and stable during the ORR kinetic processes. The material exhibits an excellent ORR activity with a half-wave potential of 0.91 V and excellent stability (insignificant attenuation after 5,000 cycles), surpassing commercial Pt/C and many other single-atom catalysts. DFT calculations further indicate that the tuning effect of Zn on the d-orbital electron distribution of Fe facilitates the stretching and cleavage of Fe-O, thus accelerating the rate-determining step. This work presents a simple strategy to fabricate well-defined diatomic coordination in single-atom ORR electrocatalysts and inspires future research on developing new syntheses to control the coordination of single-atom electrocatalysts.

Screening of transition metal-based MOF as highly efficient bifunctional electrocatalysts for oxygen reduction and oxygen evolution

Designing efficient oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) electrocatalysts is momentous for energy storage and conversion, as well as sustainable development. Herein, based on the recent prepared of two novel two-dimensional MOF materials, namely Ni–2D–SA and Ni–O–2D–SA, the replacement of Ni atoms in these two MOFs with 3d, 4d, and 5d transition metals is comprehensively investigated using density functional theory methods to screen out electrocatalysts with high bifunctional activity and stability for ORR and OER. Stability analysis indicates that some catalysts are thermodynamically and electrochemically stable. By calculating the overpotentials (ηORR and ηOER) and potential gap (∆E), it is found that Ir–2D–SA and Co–O–2D–SA possess the smallest ∆E values with 0.61 V (ηORR = 0.28 V, ηOER = 0.33 V) and 0.53 V (ηORR = 0.29 V, ηOER = 0.24 V), respectively, which are expected to be the most promising bifunctional electrocatalysts. The descriptor φ2 has proven that the binding strength for reaction intermediates is limited to active metal and environment around the active metal. Finally, all excellent catalysts have good resistance to poisoning. This work provides theoretical guidance for preparing efficient ORR and OER electrocatalysts.

N, S dual-doped carbon aerogels-supported Co9S8 nanoparticles as efficient oxygen reduction reaction electrocatalyst for zinc-air battery

The innovative design of highly active and noble-metal-free electrocatalysts for the oxygen reduction reaction (ORR) is urgently required for the widespread application of Zinc-air batteries (ZABs). This study presents a porous composite, Co9S8 @NSC, which integrates N and S co-doped carbon aerogels with Co9S8 nanoparticles to create ideal ORR electrocatalysts. The porous carbon aerogels posesess a high specific surface area, which offers abundant catalytic sites and efficient channels for the reactants and electrolytes, while maintaining a uniform distribution of nanoparticles during long-term operation. The collaboration of ORR-active Co9S8 nanoparticles and N and S co-doped carbon aerogels significantly improves ORR performance. Co9S8 @NSC demonstrates a competitive ORR activity, including a high half-wave potential (E1/2, 0.85 V), fast electron transfer kinetics (Tafel slop, 53.3 mV dec−1), and prominent long-term stability. When utilized as an air cathode catalyst in primary Zn-air batteries, the Co9S8 @NSC electrode displays a power density of 150.9 mW cm−2 and a specific capacity of 735 mAh gzn−1. Overall, this work presents a promising electrocatalyst design for ORR, which could greatly benefit the development of ZABs.

BN/Cu/CNT nanoparticles as an efficient tri-functional electrocatalyst for ORR and OER

Preparing economic, stable, and highly efficient non-precious-metal materials for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is of great significance to the development of storage technologies and energy conversion. In this manuscript, we report a novel Cu based nano-catalyst as an electrode material fabricated by complexation-reduction method. Benefit from the stable of h-NB and the good electrical conductivity of CNT, the tri-functional electrocatalyst BN/Cu/CNT displays enhanced activity towards ORR and with the high current density of 0.95 mA/cm2, which is comparable to that of commercial Pt/C catalyst (cathodic peak current: 1.05 mA/cm2). The BN/Cu/CNT also demonstrates high catalyst activity for the OER. From the rotating disk electrode and rotating ring-disk electrode tests, the number of electrons exchanged during the ORR is revealed to be 3.92, suggesting a 4e− pathway of O2 reduction to H2O. The as prepared catalyst also has good stability and superior methanol tolerance to the commercial Pt/C catalyst in alkaline medium. Thus, it is anticipated that the BN/Cu/CNT catalyst is surely helpful for providing a new space to develop Pt-free catalyst.

String of ZIF-derived hollow beaded nanocage embedded into carbon nanofiber with intensified exposed Co-Nx sites for efficient oxygen catalysis in various fuel cell devices

The rational control of Co-Nx active sites dispersion in nanomaterials is significant to construct efficient oxygen reduction reaction (ORR) electrocatalysts in fuel cells. Herein, a novel strategy for the scalable synthesis of carbon nanofiber supported hollow beaded nanocage with accessible Co-Nx sites in cavity wall (PAN-Co-ZIF-8-C-A and PAN-Co/ZIF-8-C-A) originated from zeolitic imidazolate frameworks (ZIFs) and polyacrylonitrile (PAN) is reported. Remarkably, the formed samples modified with Co-Nx sites exhibit superior ORR activity, which makes it promising ORR catalysts for microbial fuel cell (MFC) and direct methanol fuel cell (DMFC). Accordingly, the maximum power densities of MFC decorated with PAN-Co-ZIF-8-C-A and PAN-Co/ZIF-8-C-A achieve 869.6 and 888.3 mW cm−2, which are 1.17 and 1.19 times higher than that of Pt/C. In addition, the PAN-Co/ZIF-8-C-A modified DMFC exhibits comparable power density of 23.27 mW cm−2 close to Pt/C electrode (25.63 mW cm−2). Such commendable catalytic performances can be primarily attributed to the synergistic effect of hierarchical porosity for fast mass transport, high conductivity for electron migration, and well-tuned Co-Nx sites for oxygen reduction. This facile-effective optimization strategy may open a new avenue for exposing the catalytic centers of one-dimensional (1D) nanofiber and ZIFs-derived oxygen catalyst in fuel cells.

Metal-organic-framework-derived bimetallic carbon-based catalysts as efficient oxygen reduction reaction electrocatalysts

The sluggish kinetics of oxygen reduction reaction (ORR) as well as costly production of current Pt/C catalysts limit the practical application of Zn-air battery (ZAB). It is challenging to synthesize an ideal ORR catalyst with intriguing features, including a conductive network, a directed pathway for charge transfer, and abundant active sites such as bimetallic alloy nanoparticles. In this work, FeCo alloys are successfully combined due to the uniform distribution of encapsulated Fe and surface-bound Co by means of electrospinning and pyrolysis. As a result, the prepared FeCo/N-CNFs have an exceptional ORR performance (E1/2 = 0.88 V, j = 5.20 mA cm−2) that considerably outperforms Pt/C (E1/2 = 0.85 V, j = 4.75 mA cm−2). In addition, ZAB based on FeCo/N-CNFs display a superior peak power density (356.23 mW cm−2) than Pt/C-ZAB (299.29 mW cm−2). The high degree of graphitization from FeCo alloy nanoparticles, the directed charge transfer channel from a one-dimensional nanofiber structure, and the interaction between M-NX and pyridine N/graphite N species all contribute to the exceptional electrocatalytic performance.

Realizing high-efficient oxygen reduction reaction in alkaline seawater by tailoring defect-rich hierarchical heterogeneous assemblies

The development of efficient and stable oxygen reduction reaction (ORR) electrocatalysts in seawater electrolyte is the key to realizing marine resource utilization and expanding metal-air battery applications. Herein, defect-rich Fe-doped Co nanoparticles encapsulated by N-doped hierarchical carbon (D-FeCo@NHC) are rationally designed and synthesized. It is worth mentioning that the Fe doping helps to promote the generation of metal defect and adjust the electronic structure of D-FeCo@NHC. Density functional theory (DFT) demonstrate that the metal defect and carbon defect jointly optimize the d-band center of D-FeCo@NHC. As a result, in alkaline seawater electrolyte, D-FeCo@NHC display a half-wave potential of 0.874 V, and the assembled liquid Zn-air battery exhibit a high peak power density (173 mW cm−2) and ultra-long cycling stability (over 800 h). This work highlights the defect engineering in the construction of seawater-based oxygen reduction electrocatalysts, which provide a significant and promising approach for seawater-based metal-air cathode materials.

ZIF‐8‐Derived Dual Metal (Fe, Ni)‐Nitrogen‐Doped Porous Carbon for Superior ORR Performance in Universal Acid‐Base Properties Solutions

AbstractFe‐N/C catalysts have currently comparable oxygen reduction reaction (ORR) activity to Pt/C catalysts, which are up for consideration as the most promising non‐precious metal material for research. In spite of this, its development and application are limited by the Fenton effect and insufficient stability. Herein, we have fabricated a FeNi‐nitrogen‐doped porous carbon (FeNi‐NPC) catalyst using solvent thermal method, made from the bimetallic (Fe, Ni)‐doped ZIF‐8. A soft template of glucose was used to control the pore structure and active specific surface area of the catalyst. With the benefit of the electronic effect of the bimetal, FeNi‐NPC catalysts exhibit superior ORR activity and stability to Pt/C catalysts in both acidic (E1/2=0.8672 V) and alkaline (E1/2=0.8663 V) conditions. FeNi‐NPC demonstrated peak power densities in proton exchange membrane fuel cells (PEMFC) of up to 865 mW cm−2, which exceeds the currently reported M‐N/C catalysts. The work presented here will lead to the design of efficient ORR electrocatalysts in PEMFC devices.

Electrochemical aspects of Co3O4 nanorods supported on the cerium doped porous graphitic carbon nitride nanosheets as an efficient supercapacitor electrode and oxygen reduction reaction electrocatalyst

Herein, the electrochemical performance of Ce-PGCN,NS/Co3O4 as a metal-free ORR electrocatalyst and supercapacitor electrode was investigated. FESEM, TEM, BET, FTIR, XRD, EDX, FTIR, and Raman tests were used to characterize the synthesized electrocatalysts. For ORR measurements, voltammetry (CV, LSV, Choronoamperometry) and EIS tests were used to investigate the electrocatalytic activity of the electrocatalysts. And for supercapacitor measurements, the CV and GCD tests were conducted to examine the electrode's capacitance. The results of the voltammetry tests show that Ce-PGCN,NS/Co3O4 with an onset potential of −0.027 V, selecting four-electron pathway (n = 3.86), Tafel slope of 137 mV/dec, charge transfer of 570 Ω, and high durability in alkaline media (0.1 M KOH) show an excellent electrochemical performance as an ORR electrocatalyst and can be introduced as a promising substitution for commercial Pt/C catalysts. On the other hand, the results of CV in supercapacitor mode and GCD reveal that Ce-PGCN,NS/Co3O4 electrode with the specific capacitance of 789 F g−1 at the current density of 1 A g−1 and high stability in alkaline media (2 M KOH), have superior performance as a supercapacitor electrode than other electrode based on the g-C3N4. Also, it is observed that converting bulk g-C3N4 to PGCN,NS, doping Cerium atoms on the structure of the PGCN,NS, and adding Co3O4 nanorods impact the electrocatalytic activity of g-C3N4 positively.

Fe-Co spinel oxides supported UiO-66-NH2 derived zirconia/ N-dopped porous hollow carbon as an efficient oxygen reduction reaction electrocatalyst

The fuel cell is the best potential candidate to replace fossil fuels, which are a limited resource with severe environmental impacts that result in global warming and other more severe health issues. Developing a high-performing nonprecious electrocatalyst for oxygen reduction reaction (ORR) in the fuel cell is desirable but still a significant challenge. Herein, the uniform zirconia/N-dopped porous hollow carbon (ZrO2-N-C) with octahedral structure is derived from UiO-66-NH2 with not only abundant three-dimensional interconnected mesopores but also a high density of active sites. Zr-containing metal-organic framework is chosen due to the high stability and charge density, anti-toxicity, and small oxygen adsorption enthalpies of ZrO2 nanoparticles. The introduction of the SiO2 template during the synthesis of UiO-66-NH2 plays a crucial role in constructing controllable morphology, porosity, and components through the pyrolysis process. Furthermore, the synergic covalent coupling between metal oxide spinel (AB2O4) and nanocarbon effectively enhances the ORR catalytic activity. The substitution of an oxophilic metal (Fe) in Co3O4 spinel improves the electrocatalytic activity. The FeCo2O4/ES-ZrO2/NC catalyst exhibits a high catalytic activity toward ORR with an Eonset of − 0.18 V vs Ag/AgCl with a Fe/Co ratio of 3:1 in an alkaline electrolyte. The as-prepared FeCo2O4/NC exhibits not only high electrocatalytic activity but also good stability better than the Pt/C catalyst. The porosity, various valances of metals, high surface area, and N-doped C active sites are considered the main reasons for ORR's high catalytic activity.

Heterostructured Cu/CuO Nanoparticles Embedded within N-Doped Carbon Nanosheets for Efficient Oxygen Reduction Reaction

The development of cost-effective and highly efficient oxygen reduction reaction (ORR) electrocatalysts is an essential component of renewable clean energy technologies, such as fuel cells and metal/air cells, but remains a huge and long-term challenge. Here, novel heterogeneous Cu/CuO nanoparticles embedded within N-doped carbon nanosheets (Cu/CuO@NC-900) are successfully synthesized by combining a facile hydrothermal route with a solid calcination technique. Benefitting from the electronic interaction between Cu and CuO, the generated abundant highly active Cu-Nx active sites and the high conductivity of the N-doped carbon nanosheets, the resulting Cu/CuO@NC-900 material shows superior ORR performance in alkaline media, exhibiting a high half-wave potential of ~0.868 V, and a robust stability and methanol tolerance, even outperforming commercial 20 wt% Pt/C. Our study opens up a new avenue for the rational design and fabrication of efficient and durable noble-metal-free Cu-based electrocatalysts for energy conversion and storage.

Biphenylene with doping B/N as promising metal-free single-atom catalysts for electrochemical oxygen reduction reaction

The oxygen reduction reaction (ORR) is the key bottleneck in the performance of fuel cells. The rational design of efficient and inexpensive ORR electrocatalysts is a common goal for the large-scale application of fuel cells. Herein, by means of density functional theory calculations, we demonstrate that two-dimensional (2D) biphenylene (BPN) with doping B/N are metal-free single-atom catalyst candidates with the overpotentials comparable to those noble metal benchmark catalysts. The B/N doping effectively modulates the charge distribution in BPN sheets, promotes the electron transfer between doped BPN and the oxygen-containing intermediates, which results in enhancing their binding strength, and facilitating their electrochemical ORR catalytic activity. This work not only provides metal-free single-atom catalysts for ORR, but also promotes BPN nanomaterials for single-atom catalysts development and practical applications.

ZIF-8-templated synthesis of core-shell structured IPOP@MOF hybrid-derived nitrogen-doped porous carbon for efficient oxygen reduction electrocatalysis and supercapacitor

Nitrogen-doped porous carbon materials based on porous organic polymers and metal-organic framework derivatives are prepared for efficient ORR electrocatalysts and supercapacitor. The classic MOFs material ZIF-8 is selected as the core material. After ZIF-8 is pyrolyzed in an inert atmosphere at 900℃, the low-boiling Zn volatilizes, resulting in a hierarchical open-structured carbon-nitrogen material, which is beneficial to the transport of electrolytes in the electrocatalytic process. To further increase the nitrogen content, the designed nitrogen-rich IPOP-coated ZIF-8 composites were immersed in an aqueous solution of sodium dicyandiamide. The catalyst obtained by replacing Cl−and Br−in the porous organic polymer with nitrogen-containing ions and calcined at high temperature is a porous structure material containing a high concentration of active pyridine nitrogen. In addition to exhibiting superior oxygen reduction reaction (ORR) electrocatalytic activity, NC-900 shows superior stability and good methanol tolerance in comparison to commercial Pt/C catalysts in alkaline media as well as acidic media. Furthermore, in 6 M KOH electrolyte, NPCs-based supercapacitor exhibits a high capacitance of 225 F g − 1 with a current density of 1 A g − 1 and possesses good cycling stability (95.75% capacitor retention after 10,000 cycles).

Nanostructure engineering of Pt/Pd-based oxygen reduction reaction electrocatalysts.

Increasing the atomic utilization of Pt and Pd elements is the key to the advancement and broad dissemination of fuel cells. Central to this task is the design and fabrication of highly active and stable Pt- or Pd-based electrocatalysts for the oxygen reduction reaction (ORR), which requires a comprehensive understanding of the ORR pathways and mechanism. Past endeavors have accumulated a wealth of knowledge about the Pt/Pd-based ORR electrocatalysts based on structure engineering, while a systematic review of the nanostructure engineering of Pt/Pd-based ORR electrocatalysts has been rarely reported. In this review, we provide a systematic discussion about the current status of Pt/Pd-based ORR electrocatalysts from the perspective of nanostructure engineering, and we highlight the ORR pathways, mechanisms and theories in order to understand the ORR in a more complex nanocatalyst. Particularly, the underlying structure-function relationship of Pt/Pd-based ORR electrocatalysts is specifically highlighted, which will guide the future synthesis of more efficient ORR electrocatalysts.

Synthesis of hierarchically structured Fe3C/CNTs composites in a FeNC matrix for use as efficient ORR electrocatalysts.

Fe-N-C has a high number of FeN x active sites and has thus been regarded as a high-performance oxygen reduction reaction (ORR) catalyst, and combining Fe3C with Fe-N-C typically boosts ORR activity. However, the catalytic mechanism remains unknown, limiting further research and development. In this study, a precipitation-solvothermal process was used in conjunction with pyrolysis to produce a series of Fe-N-C catalysts derived from a zeolitic imidazolate framework (ZIF) that was composited with Fe3C. The prepared catalysts had a multiscale structure of ZIF-like carbon particles and rod-like structures, as well as bamboo-like carbon nanotubes (CNTs) and carbon layers wrapped with Fe3C particles while a series of studies revealed the origin of the rod-like structures and Fe3C phase. The hierarchical structure was beneficial to the enhanced electrocatalytic performance of catalysts for ORR. The optimal sample had the highest half-wave potential of 0.878 V vs. RHE, which was higher than that of commercial Pt/C (0.861 V vs. RHE). The ECSA of the optimal sample was 1.08 cm2 μg-1, with an electron transfer number close to 4, and functioning kinetics. The optimal sample exhibited high durability and methanol tolerance for the ORR. Finally, blocking different Fe active sites with coordination ions demonstrated that Fe(ii) was the main active site, indicating that Fe3C primarily served as a cocatalyst to optimize the electron structure of Fe-N-C, thereby synergistically improving the ORR activity.